Journals >Spectroscopy and Spectral Analysis
Contents
2018
Volume: 38 Issue 1
59 Article(s)
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Analysis of Detection Ability of Bacteria in Water Based on Multi-Wavelength Transmission Spectroscopy Technique
YU Hui-juan, ZHAO Nan-jing, GAN Ting-ting, DUAN Jing-bo, HU Yu-xia, LIU Jian-guo, and LIU Wen-qing
Based on a system for rapid measurement of multi-wavelength transmission spectra of bacteria, multi-wavelength transmission spectra of Klebsiella pneumoniae, Staphylococcus aureus and Escherichia coli in different concentrations of 220 to 900nm were obtained. The calibration curves of three kinds of bacteria based on tBased on a system for rapid measurement of multi-wavelength transmission spectra of bacteria, multi-wavelength transmission spectra of Klebsiella pneumoniae, Staphylococcus aureus and Escherichia coli in different concentrations of 220 to 900nm were obtained. The calibration curves of three kinds of bacteria based on the different wavelengths and the whole spectral band were established and the detection limits of Klebsiella pneumoniae, Staphylococcus aureus and Escherichia coli were calculated. The results were compared with those measured by ultraviolet-visible spectrophotometer. The results showed that the linear correlation coefficient between the experimental system and the ultraviolet-visible spectrophotometer was above 0.999 8. In addition, single measurement time of the average transmission spectrum measured by the system was 15 s, which was 30 times of the signal acquisition. By analysis based on the experimental system, the detection limits of three kinds of bacteria at different wavelengths of 220, 300, 350, 400, 500, 550 nm and full spectrum were all better than those of ultraviolet-visible spectrophotometer. And the detection limit calculated by the full spectrum of the multi-wavelength transmission spectra was the lowest. The detection limit of Klebsiella pneumoniae, Staphylococcus aureus and Escherichia coli were 1.60×104, 1.06×104 and 1.16×104 cells·mL-1. The results provide the basic data for the further development of the rapid and quantitative detection technology of the multi-wavelength transmission spectra of bacteria in water..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 1 (2018)
Applications of Infrared and Raman Spectroscopy in Metal Hydrides and Deuterides Structure Analysis
CHEN Miao, PENG Shu-ming, ZHOU Xiao-song, LONG Xing-gui, and FU Yi-bei
Infrared and Raman spectroscopy are powerful technologies in metal hydrides structure analysis. If theoretical calculation is combined with Infrared and Raman analysis technology, they can provide information on the local bonding environment between metal atoms and hydrogen atoms of binary (MgH2, CaH2, AlH3) and ternarInfrared and Raman spectroscopy are powerful technologies in metal hydrides structure analysis. If theoretical calculation is combined with Infrared and Raman analysis technology, they can provide information on the local bonding environment between metal atoms and hydrogen atoms of binary (MgH2, CaH2, AlH3) and ternary (Mg2FeH6) metal hydrides. Thereby, different phase structures of metal hydrides can be identified, they can also provide structure difference information in ternary metal hydride M2RuH6 (M=Ca, Sr, Eu) due to the different metal atom composition, and the structure differences between ternary metal hydride and deuteride also can be obtained. Moreover, the structure change of metal hydride can be monitored during compression and decompression by in situ Raman spectroscopy analysis, which helps us interpret diffraction data deeply. In order to avoid the disadvantageous effect of air and moisture on FTIR experiment results, PAIR spectrum was developed to increase the intensities of Infrared and Raman combination bands. Infrared and Raman spectroscopy even can be applied on metal tritides structure analysis, and it can provide the information on the local bonding differences between metal atoms and hydrogen isotopic atoms which helped us research the hydrogen isotopic effect better. Raman spectroscopy has also been used to in situ monitoring of the formation and decomposition of metal hydride under high pressure or high temperature, and has also been successfully applied in hydrogen isotope mixture gases analysis, such as tritium analysis and management in ITER project. If structure analysis is combined with hydrogen isotope mixture gas analysis by Infrared and Raman, the reaction kinetics and isotopic effect between metal and hydrogen isotope gases reaction can be researched..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 8 (2018)
A Hybrid Plasmonic Waveguide for Nanolaser Applications
LI Wen-chao, WANG Ya-juan, HE Jia-huan, FENG Dan-dan, LI Zhi-quan, TONG Kai, and GU Er-dan
In this paper, a novel hybrid plasmonic waveguide with a metal ridge and a dielectric layer of low refractive index was demonstrated. We numerically simulated the waveguide by using finite-element method. The COMSOL Multiphysics Software is a superior numerical simulation software to simulate the real physical phenomenIn this paper, a novel hybrid plasmonic waveguide with a metal ridge and a dielectric layer of low refractive index was demonstrated. We numerically simulated the waveguide by using finite-element method. The COMSOL Multiphysics Software is a superior numerical simulation software to simulate the real physical phenomena based on finite element method. On the basic of the COMSOL Multiphysics Software, a three-dimensional model was built. Using the modal analysis module and the frequency domain analysis module, we analyzed the normalized mode scaling factor, distance, lasing threshold and quality factor. The results indicated that the waveguide structure can reach good deep-subwavelength mode confinement while maintaining long distance at the 370 nm working wavelength. Compared to the previously reported structure with a metal plate, it has better waveguide performance. When this structure applied to nanolasers, the electric field distribution in nanolasers is stable and concentrated on a tiny area. In the case of good waveguide characteristic, the nanolasers can keep low gain threshold and high quality factor of the resonant cavity at the 370 nm working wavelength. By comprehensive consideration, the optimal size can be choosed as ｒ＝80 nm, d＝45 nm. In this case, the effective mode area was , the distance was 1 668 nm, the lasing threshold was 1.68, and the quality factor was 74.5. Finally, the emission spectrum was obtained by simulation at the optimal size. The emission wavelength was 360 nm, and the output power was increased 3 100 times than the input power. This structure affords technical support to miniaturization and integration of lasers which have broad application prospects in the field of the biomedical and optical communications..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 15 (2018)
Molecular Structure and Spectrum of GaN under the Radiation Fields
YIN Wen-yi, LIU Yu-zhu, LIN Hua, LI Bing-sheng, and QIN Chao-chao
Based on the density functional theory DFT/B3LYP at 6-311++g(d, p) level, the ground states of GaN molecule under different external electric fields were optimized. The influence of external electric field ranging from 0 to 0.025 a.u. on the geometrical parameters, dipole moment, total energy, energy gap, Infrared specBased on the density functional theory DFT/B3LYP at 6-311++g(d, p) level, the ground states of GaN molecule under different external electric fields were optimized. The influence of external electric field ranging from 0 to 0.025 a.u. on the geometrical parameters, dipole moment, total energy, energy gap, Infrared spectrum, Raman spectrum and UV-VIS absorption spectrum intensity were studied. The results showed that the changes of molecular structure were strongly dependent on the applied electric field. As the electric field changed from 0 to 0.025 a.u., the bond length of GaN molecular decreased, while the electric dipole moment was proved to be decreasing and the total molecular energy increased all the time. The energy gap of Eg was found to decrease with the increasing external field. The IR vibration spectrum of GaN molecule showed an observable blue shift and the Raman vibration spectrum appears blue shift phenomenon too. The oscillator strength of UV-VIS absorption spectrum was proved to be repeating the changes of the first decreasing and then increased. The ultraviolet absorption peak was red-shifted with the increase of the field intensity..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 21 (2018)
Broad Band Source Based Interferometric Microscopy for Fast Reading Internal Fingerprint
WANG Jin-yu, LEI Ming, YIN Shao-yun, LI Gang, and WANG Yue-feng
Using fingerprint to identify an individual has been accepted since the nineteenth century, and the fingerprint has become one of the most widely used biometric characteristics. Current modern fingerprint recognition systems are based on the print pattern of the finger surface, and the most commonly used fingerprint seUsing fingerprint to identify an individual has been accepted since the nineteenth century, and the fingerprint has become one of the most widely used biometric characteristics. Current modern fingerprint recognition systems are based on the print pattern of the finger surface, and the most commonly used fingerprint sensors are based on frustrated total internal reflection, which produce fingerprint images by reflecting light from only those parts of the skin-glass interface that are not in contact. Those are not robust against spoof attaching, and will fail when finger get dirty, wet or even get flattened associated with age. Nevertheless, in the depth of 220～550 μm under the external fingerprint, there is a layer of skin inside a finger with the same topographical features as the surface (external) fingerprint. This internal layer serves as a “master template” from which the external fingerprint grows. Moreover, within the internal structures of a finger, the sweat pores and microvascular structure will also follow the template. we name it as internal fingerprint, which will not change during the whole life period. Internal fingerprint is difficult to make a fake pattern. In addition, it does not have creases, never dirty, scarred or too wet/dry to make sensor difficult to produce good quality images. Therefore, with High security and robustness, internal fingerprint is ideal as a new way for biometric identification. Currently, there are not many different types of sensors on the market that are able to gather information from the inside of a finger. Optical coherence tomography (OCT) possesses optical sectioning capability and is able to image deep in tissue. By fast standard OCT techniques, such as swept-source OCT (SS-OCT), which can first build a 3-D data volume by point-by-point raster-scanning of A-scan (signal signature along optical axis) , and then a single en face 2-D image at a specific depth can be reconstructed. It needs large memory to store the 3-D data and takes longer time to reconstruct the en face images, but its feasibility is limited. In contrast, full-field OCT (FFOCT) can acquire a single en face image without having to acquire 3-D data set, and therefore, produce much smaller image size (a few Mb) and potentially can be faster. Boccara group has implemented an internal fingerprint reader with InGaAs camera based FFOCT system.In this paper, with cheap CCD camera, we implemented a fast interferometric microscopy with broad band light source for taking the internal fingerprint under the finger skin. The broad band white light laser provided axial resolution of 3.5 μm, with low numerical number illumination, and penetration depth is increased. Thanks to the space incoherence, the arrayed detector can extract the full field en face tomography image without scanning. We demonstrated the 3D structure of the internal fingerprint, including its sweat pores structure, obtained the 2D internal fingerprint image at the speed of 0.4 s per frame. Our work confirmed the capacity of the internal fingerprint for high fidelity biometric identification and provided interferometric microscopy as its reader..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 26 (2018)
Research on Genetic Algorithm Based on Mutual Information in the Spectrum Selection
KONG Qing-qing, GONG Hui-li, DING Xiang-qian, and LIU Ming
It is vital to establish an accurate and robust quantitative model in near-infrared spectroscopy. The whole spectrum modeling can increase the computational time of modeling and forecasting, and reduce the robustness and precision. Therefore the effective variable selection method is very important for model constructiIt is vital to establish an accurate and robust quantitative model in near-infrared spectroscopy. The whole spectrum modeling can increase the computational time of modeling and forecasting, and reduce the robustness and precision. Therefore the effective variable selection method is very important for model construction. To address this problem, this paper proposed a genetic algorithm based on mutual information (GAs-MI) to select features. Mutual information filtered out a large number of unrelated information and redundant information. Genetic algorithm further selected the features with high discernment. Shapley value method was introduced to reduce the randomness of artificial setting parameters in the mutation process of genetic algorithm. In order to validate the validity of the algorithm, 273 representative tobacco samples were selected as the experimental materials. 182 samples were randomly selected to construct the PLS quantitative model of tobacco nicotine,and the remaining samples were used as the test set. The Correlation Coefficient (R), the Root Means Square Error of Cross Validation (RMSECV) and the Root Mean Square Error of Prediction (RMSEP) were used as the model evaluation indexes. The experimental results showed that the model established by the selected wavelength was simpler and more predictive..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 31 (2018)
Convolutional Neural Network Application in Prediction of Soil Moisture Content
WANG Can, WU Xin-hui, LI Lian-qing, WANG Yu-shun, and LI Zhi-wei
The technology of near infrared spectroscopy that has unique advantage in the prediction of soil moisture content is a convenient and effective method. Convolutional neural network (CNN) is a deep learning model with high performance. Using CNN, effective features data can be extracted from complex spectral data and thThe technology of near infrared spectroscopy that has unique advantage in the prediction of soil moisture content is a convenient and effective method. Convolutional neural network (CNN) is a deep learning model with high performance. Using CNN, effective features data can be extracted from complex spectral data and the inner structure of feature data can be learned. Compared with traditional surface learning models, convolutional neural network has more powerful modeling capability. In this research, the CNN was used to predict the soil moisture content by near infrared spectroscopy. An efficient modeling method of CNN for spectral regression was proposed. The pretreatment process of spectral data was simplified and the accuracy of spectral prediction was improved by this modeling method. In this paper, firstly, the simple pretreatment was used to treat the spectral reflectance data of soil samples under different moisture contents. Principal component analysis was used to reduce the amount of spectral data and the correlation of the features. The processed spectral data was transformed into 2-dimensional spectral information matrixes to meet the special learning structure of CNN. Secondly, the convolutional neural network was used to build the regression model for the prediction of soil moisture content. The first four stages of this CNN model were composed of two types of layers: convolutional layers and pooling layers. Inner features of the input spectral data were obtained by composing convolutional layers and pooling layers, each transforms the representation at one level into a representation at a higher, slightly more abstract level. With the composition of enough such transformations, very effective inner features of spectral data can be extracted. There were two key ideas behind the CNN model that can reduce the number of parameters of the network: local connections and shared weights. In addition, these ideas can also improve the generalization performance of the CNN model. The model structure and parameters were optimized by carrying out experiments. Finally, the CNN model with improved regression structure of soil spectral data was built for the prediction of soil moisture content. The CNN model was compared with the BP, PLSR and LSSVM models, and these three traditional models were commonly used in the prediction of soil moisture content. The results showed that when the number of training samples reached to some degree, the prediction accuracy and regression fitting degree of the CNN model were higher than those of the traditional models. The performance of the CNN model were much higher than the BP neural network which had the same network training method with the CNN model, but slightly lower than the PLSR and LSSVM models when a small number of training samples were used in the modeling. The prediction accuracy of the CNN model greatly increased with the number of training samples growing. So did the regression fitting degree of the CNN model. In the end, the performance of the CNN model was significantly better than the traditional models. Therefore, the CNN method could be used to effectively predict the soil moisture content by the near infrared spectral data, and better results are obtained when more training samples are involved in modeling..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 36 (2018)
Noninvasive Human Triglyceride Detecting with Near-Infrared Spectroscopy
YUAN Jing-ze, LU Qi-peng, WU Chun-yang, DING Hai-quan, GAO Hong-zhi, LI Wan-xia, and WANG Yang
To facilitate noninvasive detection of human triglyceride (TG) in blood, near infrared spectroscopy (NIRS) was applied to quantitatively analyze the TG level of single person. By optimizing the proper NIRS detection band (5 700～5 600 and 4 600～4 400 cm-1) in in-vitro experiment, preferably designing the fiber probe, anTo facilitate noninvasive detection of human triglyceride (TG) in blood, near infrared spectroscopy (NIRS) was applied to quantitatively analyze the TG level of single person. By optimizing the proper NIRS detection band (5 700～5 600 and 4 600～4 400 cm-1) in in-vitro experiment, preferably designing the fiber probe, and comparatively evaluating several preprocessing algorithms, we intend to further promote the non-invasive detection accuracy and stability of single-person TG level. Then we noninvasively collected 54 samples of spectral data from the same volunteer and made quantitative analysis for TG level. Savitzky-Golay (SG) combined with partial least squares (PLS) was confirmed to be the most robustness calibration model. The optimal analysis of the predictive 1 and 2 sets is as follows. The standard deviation (RMSEP) was 12 and 12.8 mg·dL-1, respectively; the relative standard deviation (RSD) was 16.25% and 17.33%, respectively. The prediction accuracy was ideal and able to be used for routine monitoring of single TG. In view of the well performance of SG-PLS model in non-invasive detection of single-person TG level and the trend of daily variation, NIRS analysis technology has potential for human TG non-invasive detection and daily management..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 42 (2018)
Experimental Study on the Influence of the Radiation Background on the Variation in Thermal Infrared Radiance of Loaded Rock
HUANG Jian-wei, LIU Shan-jun, XU Zhong-yin, MA Chun-yan, and WU Li-xin
Previous studies have shown that the thermal infrared radiation of rock surface changes corresponding to the stress in the rock loading process. The effective extraction of radiation variation information depends on the influence from background radiation. Thus, this study aims to analyze the variety of thermal infrarePrevious studies have shown that the thermal infrared radiation of rock surface changes corresponding to the stress in the rock loading process. The effective extraction of radiation variation information depends on the influence from background radiation. Thus, this study aims to analyze the variety of thermal infrared spectrum for loaded rock under different experimental conditions. The thermal infrared radiation experiments of loaded granite were carried out in both indoor and outdoor conditions. The relationship between radiation variation and stress under different experimental condition was investigated, and the characteristic of radiation information caused by stress was analyzed. Furthermore, we compared the sensitive waveband to stress in thermal infrared detection under indoor and outdoor conditions. The results showed that the radiation background had a significant effect on the radiation changes of loaded rock. It was found that the infrared radiation changed more significantly, and correlated more closely to stress in the outdoor condition, while the sensitive waveband is wider due to the relatively weak background radiation. It is more accurately and reasonably for detecting the thermal infrared radiation of loading rock in the outdoor condition. The 8.0～11.8 μm wave range can be considered as the effective waveband for granite stress monitoring using thermal infrared remote sensing technology..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 49 (2018)
Application of Near Infrared Spectroscopy in the Study of Gems
LI Xiao-jing, YU Lan, and ZU En-dong
At present, the application of infrared spectroscopy in the study of gem identification has been more concentrated in the mid-infrared range of 400~4 000 cm-1, and related research on the near-infrared region of the spectrum 4 000~10 000 cm-1 has been rarely done. This paperstudied the gemstones, jades and organic gemsAt present, the application of infrared spectroscopy in the study of gem identification has been more concentrated in the mid-infrared range of 400~4 000 cm-1, and related research on the near-infrared region of the spectrum 4 000~10 000 cm-1 has been rarely done. This paperstudied the gemstones, jades and organic gems’ NIR spectroscopy by Fourier transform infrared spectrometer. The results showed that gem mineral’s NIR widespread presence of water absorption peak, whichwas mainly for different types of water combination tone and overtone, also can appear lower-energy electronic transition absorption peaks. 5 200 cm-1± was a combination tone of water molecules, and 7 000 cm-1± was a overtone of —OH while 5 898 and 7 849 cm-1± centered strong broad absorption band was a lower-energy electronic transition absorption peak. When there was only 7 000 cm-1± absorption peak, description that water in gem mineral only existed in the form of —OH. When there were 5 200 and 7 000 cm-1± absorption peaks at the same time, description that water existed in the form of molecules and —OH.The characteristics of organic gems were 5 200 cm-1± for the combination tone of NH stretching vibration and amide II and 7 000 cm-1± for the first overtone of NH stretching vibration. The near-infrared spectrum absorption peaks of different varieties of organic gems had different characteristics of position, shape and the relation strength. The characteristics of organic filling gems were 4 061, 4 683 cm-1± for the combination tone of benzene ring’s CH stretching vibration and bending vibration and 4 620, 4 683 cm-1± for the combination tone of CH stretching vibration and benzene ring skeleton vibration. The absorption peak associated with benzene ring, generally indicates that the sample through the fill process..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 54 (2018)
Study on Rapid Determination of Oligosaccharides in Soybean Products by Near-Infrared Reflectance Spectroscopy
WANG Xiao-xiao, LI Jun-tao, SUN Xiang-li, HAN Miao-miao, CHEN Yi-qiang, and ZHANG Li-ying
The present study investigated the possibility of using near-infrared reflectance spectroscopy (NIRS) for quantitative determination of oligosaccharides, including sucrose, raffinose and stachyose in soybean products. One hundred and sixty samples (de-hulled soybean meal, extruded soybean meal, extruded full-fat soybeaThe present study investigated the possibility of using near-infrared reflectance spectroscopy (NIRS) for quantitative determination of oligosaccharides, including sucrose, raffinose and stachyose in soybean products. One hundred and sixty samples (de-hulled soybean meal, extruded soybean meal, extruded full-fat soybean and fermented soybean meal) were collected and screened, and furthermore forty artificial soybean meal samples were prepared. Calibrations were performed by partial least squared algorithm with different derivatives, multiplicative scatter correction or normalization vector spectral pretreatment. The coefficients of determination for calibration (R2cal), coefficients of determination for cross validation (R2cv) and RPDcv in models were 0.99, 0.95, 0.98; 0.98, 0.94, 0.97; 7.24, 4.13, 5.98; respectively. The results supposed that NIRS can be a quantitative determination method of oligosaccharides in soybean products except fermented soybean meal..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 58 (2018)
Infrared Spectroscopic Analysis of the Production Process of Larch Bark Proanthocyanidins
JIANG Ze-ming, ZHOU Tian-tian, BU Hong-yang, ZHANG Li-ping, SUN Su-qin, and MA Fang
In order to evaluate existing producing process of larixgmelinii bark proanthocyanidins, understand the changes of the component content in each step, we used Tri-level infrared spectroscopic to identify, which employed the Fourier transform infrared spectroscopy(FTIR), the second derivative infrared spectroscopy(SD-IRIn order to evaluate existing producing process of larixgmelinii bark proanthocyanidins, understand the changes of the component content in each step, we used Tri-level infrared spectroscopic to identify, which employed the Fourier transform infrared spectroscopy(FTIR), the second derivative infrared spectroscopy(SD-IR) and two-dimensional correlation infrared spectroscopy. The results indicated that the FTIR spectrograms of the product of each process in shape was very similar. We found that some substances characteristic peak disappeared or offseted, reflecting the changes of component content of samples. With the improvement of production process, the purity and structure of samples have been more and more near to the standard sample, but still contained some other substance. The second derivative infrared spectroscopy not only tested and verified the analysis results of FTIR, but also improved the resolution ratio which was helpful to show differences that were not manifested in FTIR. Within the scope of the 830 to 1 310 cm-1,2D-IR has more significant differences in positions, strength and numbers of automatically peaks. Therefore, we could conclude from the Tri-level infrared spectroscopic identification that the purity in proanthocyanidins is higher and higher with the improvement of production process. And the structures of samples we get finally are similar to that of standard sample, but still contains a small number of impurities.
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 62 (2018)
Near Infrared Spectroscopy for Determination of the Geographical Origin of Huajiao
WU Xi-yu, ZHU Shi-ping, HUANG Hua, XU Dan, and GUO Qi-gao
Identification method of 205 Huajiao samples from 8 different geographical origins by near infrared spectroscopy coupled with principal component analysis (PCA) and pattern recognition based on discriminant partial least squares (DPLS) was proposed in this paper. In the spectra region between 12 500～3 800 cm-1, predictIdentification method of 205 Huajiao samples from 8 different geographical origins by near infrared spectroscopy coupled with principal component analysis (PCA) and pattern recognition based on discriminant partial least squares (DPLS) was proposed in this paper. In the spectra region between 12 500～3 800 cm-1, predictive models with different pretreatments of calibration set were built separately, and robust models indicating these geographic origins of Huajiao samples could be achieved using DPLS pattern recognition method. The correct identification rates of the independent validation set were between 85.37%~97.56%, in which DPLS discriminant model with standard normal variate (SNV) or multiplicative scatter correction (MSC) preprocessing was best. The method was effective in Huajiao origin recognition..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 68 (2018)
Preparation and Raman Investigation of High Pressure ICF Targets
WEN Cheng-wei, SHEN Chun-lei, YU Ming-ming, XIA Li-dong, WANG Kai, and LI Hai-rong
The quantitative analysis and monitoring of hydrogen isotopes, including hydrogen (H2), hydrogen deuterium (HD), hydrogen tritium (HT), deuterium (D2), deuterium tritium (DT) and tritium (T2), are of great significance in the field of energy and environment. Due to its non-destructive and non-contact analytical charactThe quantitative analysis and monitoring of hydrogen isotopes, including hydrogen (H2), hydrogen deuterium (HD), hydrogen tritium (HT), deuterium (D2), deuterium tritium (DT) and tritium (T2), are of great significance in the field of energy and environment. Due to its non-destructive and non-contact analytical characteristics, laser raman spectroscopy (LRS) has become an important analyzing method for hydrogen isotopes quantification and in-line monitering. In the international thermonuclear experimental reactor (ITER) and savannah river factory (SRF) laser raman spectroscopy has been extensively used for qualitative and quantitative analytical purposes. Promising results are also obtained in raman system at the Karlsruhe Tritium Neutrino Experiment (KATRIN), which is targeted to measure the neutrino mass by means of high precision electron spectroscopy of the β-decay of tritium. In this paper, high pressure gas targets for inertial confinement fusion (ICF) experiments were prepared and studied by Raman spectroscopy. The composition of high pressure deutrium-tritium mixtrures were obtained by analyzing the rota-vibrational spectra of above molecules as a first approximation. The obtaining results were compared with mass spectroscpy measurements and the technological parameters for target fabrication were verified. The experiments showed that a precision of 1% can be obtained for deuterium (D2), deuterium tritium (DT) and tritium (T2) when integration time increased to 1 minute using a commercial instrument (LabRAM HR800,Jobin Yvon), though modification was still needed to achieve a even higher precesion. The pressure shifts for deuterium (D2), deuterium tritium (DT) and tritium (T2) were tentatively investigated and compared with previous studies. At the same time, the composition evolution of high pressure deuterium tritium gas mixture was also monitored during 6 months’ storage time. The experimental results show ed that due to the interplay of gas permeation and tritium decay effects, the gas composition did not change though the total gas pressure within the target decreased continuously with time..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 73 (2018)
Preparation and Spectral Characterization of HNIW and DNT Cocrystal
LIU Ke, ZHANG Gao, CHEN Zhi-qun, SHU Yuan-jie, and LUAN Jie-yu
As a new high energy explosive, it is particularly crucial for HNIW (2, 4, 6, 8, 10, 12-hexanitrohexaazaiso-wurtzitane) to modify the comprehensive performance especially under the modern battlefield environment. Unlike the ordinary modifying method such as recrystallization and polymer coating, the formation of HNIW cAs a new high energy explosive, it is particularly crucial for HNIW (2, 4, 6, 8, 10, 12-hexanitrohexaazaiso-wurtzitane) to modify the comprehensive performance especially under the modern battlefield environment. Unlike the ordinary modifying method such as recrystallization and polymer coating, the formation of HNIW cocrystal with low sensitivity micromolecule explosive can achieve the modification from the inner composition and the invariant inherent molecular structure. Consequently, HNIW/DNT(dinitrotoluene) cocrystal was prepared by slow solvent evaporation method at room temperature. Using X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy analysis, the crystal structure, intermolecular non-bonding interactions and comprehensive properties of the cocrystal were characterized and analyzed. The characterization results showed that a new sharp peak appeared in the co-crystal PXRD diffraction pattern, which indicated that the cocrystal was a totally new non-solvated crystalline phase rather than the crystal transformation product. In fourier transform infrared spectroscopy and Raman spectroscopy, the peak shifts and peak height, peak width of some characteristic absorption peak changed, which confirmed the formation of HNIW/DNT cocrystal. And the intermolecular interactions was mainly the result of intermolecular interactions between HNIW and DNT molecular..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 77 (2018)
Raman and IR Study on Silicon Films at Transition Regime
FAN Shan-shan, GUO Qiang, YANG Yan-bin, CONG Ri-dong, YU Wei, and FU Guang-sheng
A series of silicon films at transition regime from amorphous to microcrystalline phase with different hydrogen dilution ratios were fabricated by the plasma-enhanced chemical vapor deposition (PECVD) technique, and the microstructural properties of the films at transition regime from amorphous to microcrystalline phasA series of silicon films at transition regime from amorphous to microcrystalline phase with different hydrogen dilution ratios were fabricated by the plasma-enhanced chemical vapor deposition (PECVD) technique, and the microstructural properties of the films at transition regime from amorphous to microcrystalline phase were studied using Raman scattering and Fourier transform infrared spectroscopy. The paracrystalline structure was used to elucidate the microstructure of silicon films at transition regime from amorphous to microcrystalline phase. The paracrystalline fraction (fp) as a signature of intermediate range order for the silicon films was proposed. The results indicated that the transition from amorphous to microcrystalline phase took place with the increase of hydrogen dilution. Silicon film grown just below transition edge was characterized by high hydrogen content, compact structure and enhanced medium range order, and hydrogen mainly passivated the surface of the film. Silicon film grown just above transition edge was characterized by low hydrogen content, high crystalline fraction and low interface phase, and hydrogen etching played an important role during film growth. The microstructure topography detected by scanning electron microscope verified the results from Raman scattering and Fourier transform infrared spectra. Silicon films had good microstructural properties at transition regime from amorphous to microcrystalline phase, especially around transition edge and were available as intrinsic layer for the thin film solar cells..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 82 (2018)
Gold Nanocluster Assembled Nanoislands for Surface-Enhanced Raman Scattering Application
LIANG Shu-yan, LIU Hong-mei, MU Yun-yun, ZHAI Tian-rui, and ZHANG Xin-ping
Surface-enhanced Raman scattering (SERS) has been applied in a range of fields for its high sensitivity and its potential applications in several critical social areas. Reproducible fabricating the SERS substrates in large scale and low cost has been one of the hot topics in SERS researches. In this paper, we assembledSurface-enhanced Raman scattering (SERS) has been applied in a range of fields for its high sensitivity and its potential applications in several critical social areas. Reproducible fabricating the SERS substrates in large scale and low cost has been one of the hot topics in SERS researches. In this paper, we assembled the solution processed gold nano clusters with the diameter less than 5 nm into the randomly distributed gold-nanoislands by optimizing the annealing process. We found that the assembling process was slow and could be finely controlled as the annealing temperaturewas within the range of 150~210 ℃. By controlling the assembling process, we can reproducibly fabricate a kind of homogeneous SERS substrate with high density of “hot spots” in large area. These SERS substrates had intense surface enhanced Raman scattering to the monolayer adsorbed on the surface of the gold-nanoislands, and yielded a global enhancement factor as large as 106~107 for the samples annealed at 150~210 ℃. We found that, under the same conditions, the gold nano clusters were firstly fused into tiny gold-nanoislands with the diameter of 10~20 nm as the annealing temperature was within the range of 150~180 ℃. As the annealing temperature was increased to 190~210 ℃, the matrix of tiny gold-nanoislands (10~20 nm) and large gold nanoislands (50~70 nm) could be formed. The spectral characterization has shown that the samples consist of the matrix of tiny and large gold-nanoislands have a higher global enhancement factor than the samples consist of barely tiny gold-nanoislands. At 220 ℃, the gold nanoclusters completely fused into large gold-nanoislands. However, the gaps between the large gold-nanoisland also increased with the fusing process, which induced an exponential decay of the intensity of the electromagnetic field between the gold-nanoislands. As a result, the samples annealed at 220 ℃ has the lowest SERS enhancement factor. In this work, we demonstrated the mechanism of how low-temperature annealing process affects the assembling of the gold nanoclusters. We also showed the relationship between the morphology of the gold-nanoisland and the SERS properties. We provided a facial rout for controllable fabricating the high quality SERS substrates, which has potential applications in the future..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 87 (2018)
Signal Processing Method for Raman Spectra Based on Matching Pursuit
WANG Xin, HE Hao, FAN Xian-guang, and TANG Ming
Raman spectroscopy, as a high sensitive, non-invasive vibrational molecular spectrocopy technique, plays a significant role in many fields such as pharmaceutical, biology and analytical chemistry etc. However, due to the weak Raman scattering intensity, the measured Raman signal is always contaminated by noise. EspeciaRaman spectroscopy, as a high sensitive, non-invasive vibrational molecular spectrocopy technique, plays a significant role in many fields such as pharmaceutical, biology and analytical chemistry etc. However, due to the weak Raman scattering intensity, the measured Raman signal is always contaminated by noise. Especially in the short exposure time, the SNR (signal to noise ratio) of collected Raman spectra is extremely low. Therefore, this paper proposed a signal reconstruction method based on matching pursuit algorithm, which is used to extract Raman signals from the low SNR Raman spectra. The method first finds the position of the characteristic peak on the average spectrum by threshold iterative method, and estimates the interval of the peak according to the location of the peak and peak interval, with a Gaussian density function to generate a dictionary. In the noise spectrum, according to the position and interval of the characteristic peak, it is divided into the signal interval and the non-signal interval. On the signal interval, the matching pursuit algorithm is used to reconstruct the Raman signal covered by noise. The algorithm not only can primely approximate the Raman signal which is covered in the noise, but also deducts the baseline in the procession of reconstructing the signal, and does not need any baseline correction further. The performances of the proposed algorithm and conventional algorithms were compared. The results show that the proposed algorithm can recover the Raman signals in the condition of low SNR. Different with the conventional de-noise algorithms, algorithm of this paper process the baselines and the random noises in Raman signals simultaneously, and the results have been proved good. So there is no need to use different algorithms to process the baselines and noises separately. Furthermore, in the aspect of algorithm, we creatively applied the matching pursuit algorithm to solve the sparse approximation of Raman signals..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 93 (2018)
Preparation of Three-Dimensional Hotpot SERS Substrate with Sliver Nanocubes and Its Application in Detection of Pesticide
YANG Huan-di, LIN Xiang, LIU Yuan-lan, ZHAO Hai-yan, and WANG Li
In this paper, silver nanocubes were prepared by seed growth method. The prepared sliver nanocubes showed a uniform size distribution, with a RSD of 7.2%, according to scanning electron microscopy (SEM) characterization. CTAC on the surface of silver nanocubes were replaced by citrate. Based on SLIPS substrate with supIn this paper, silver nanocubes were prepared by seed growth method. The prepared sliver nanocubes showed a uniform size distribution, with a RSD of 7.2%, according to scanning electron microscopy (SEM) characterization. CTAC on the surface of silver nanocubes were replaced by citrate. Based on SLIPS substrate with super lubrication properties, three dimensional SERS substrate was constructed with sliver nanocubes as building block. The three dimensional SERS substrate was used to detect tricyclazole and thiram in water and ethanol. The limit of detection for detecting tricyclazole and thiram could reach 52.8 and 41.6 nmol·L-1, respectively. The experiment results show that the three dimensional SERS substrate has an excellent detection sensitivity. Therefore, the three dimensional SERS substrate has great significance for detecting pesticide in real-world environment..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 99 (2018)
Scientific Analysis of Garnet Beads Unearthed from Tomb Dated to Han Dynasty in Jiuzhiling, Hepu, Guangxi
WANG Ya-wei, DONG Jun-qing, and LI Qing-hui
To ascertain the material, making technique, and possible sources of raw materials of some purple gemstone bead ornaments unearthed from the tomb dated to Han Dynasty in Jiuzhiling, Hepu, Guangxi, eight beads were analyzed by X-ray fluorescence spectroscopy (XRF), Raman spectroscopy and Digital microscope system. The rTo ascertain the material, making technique, and possible sources of raw materials of some purple gemstone bead ornaments unearthed from the tomb dated to Han Dynasty in Jiuzhiling, Hepu, Guangxi, eight beads were analyzed by X-ray fluorescence spectroscopy (XRF), Raman spectroscopy and Digital microscope system. The results of XRF and Raman spectroscopy showed that these beads were made of pyralspite garnet group endmember species. They have similar chemical compositions to that of almandine-garnets, except one sample attributed to almandine-pyrope garnet. We discussed the processing techniques and the possible sources of the garnet beads based on the mark evidence obtained by Digital microscope system, and the recent results of archaeological and scientific researches. The rotary grinding-stone technique and the spherical polishing-leather bag technique were used for grinding and polishing these beads, and a double-diamond drills was used to drill the beads from both sides. It can be concluded that the batch of garnet gemstone beads were imported to Hepu from South Asia by way of Southeast Asia or from South Asia along maritime Silk Road. The beads analyzed in this paper are important evidences of the Maritime Silk Road trade in Han Dynasty. It is significant for the studies of the history and cultural exchange on the maritime Silk Road..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 104 (2018)
Researching of Non-Destructive Detection for Citrus Greening Based on Confocal Micro-Raman
LIU Yan-de, XIAO Huai-chun, SUN Xu-dong, WU Ming-ming, YE Ling-yu, HAN Ru-bing, ZHU Dan-ning, and HAO Yong
It is great significance to study the rapid detection for citrus greening because citrus greening is increasingly serious harmful for citrus fruit trees. In this paper, using Raman spectroscopy technology combined with partial least squares discriminant analysis (PLS-DA) method was used to explore the feasibility aboutIt is great significance to study the rapid detection for citrus greening because citrus greening is increasingly serious harmful for citrus fruit trees. In this paper, using Raman spectroscopy technology combined with partial least squares discriminant analysis (PLS-DA) method was used to explore the feasibility about rapid diagnosis citrus greening and the classification of disease. The Raman spectra of citrus leaves were obtained and leaves were divided into five types: slight greening, moderate greening, serious greening, nutrient deficiency and normal by common PCR. In the range of 715~1 639.5 cm-1, the three methods of first derivative, baseline correction and polynomial fitting were used to eliminate the spectral background to highlighted the characteristics peak of Raman spectra. Polynomial fitting were taken two times, three times and four times fitting in this method respectively, compared with the other two methods of first derivative and baseline correction for eliminated the spectral background. Combining with the least squares support vector machine (LS-SVM) and partial least squares discriminant analysis (PLS-DA), wedeveloped the discriminant models. By comparison, the effect of eliminated the spectral background using polynomial fitting was better than the other two methods. Especially the effect of PLS-DA model was taken two times fitting was the best The correlation coefficient of prediction (RP) was 0.98, while the root mean square error of prediction (RMSEP) was 0.67. The total misjudgment rate in the least was 0 andthe effect of LS-SVM model using the method of baseline correction was the worst, while the total misjudgment rate at maxium was 40%. The results showed that it was feasible to study the rapid identification of citrus greening by Raman spectroscopy technology, and a new approach to study the non-destructive detection of citrus greening was provided..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 111 (2018)
An Application to Quantitative Analysis of Hg(Ⅱ) with L-Cysteine Molecular Probe by Surface-Enhanced Raman Spectroscopy
ZHANG Cai-hong, ZHOU Guan-ming, ZHANG Lu-tao, LUO Dan, YU Lu, and GAO Yi
In this paper, a detection of trace Hg(Ⅱ) was based on silver nanorods by surface-enhanced Raman spectroscopy (SERS)activity. It was discussed the probe types, which explored that the L-cysteine with a high selectivity and sensitivity for Hg(Ⅱ). The UV/Vis spectra was used to characterize the silver nanorods and its moIn this paper, a detection of trace Hg(Ⅱ) was based on silver nanorods by surface-enhanced Raman spectroscopy (SERS)activity. It was discussed the probe types, which explored that the L-cysteine with a high selectivity and sensitivity for Hg(Ⅱ). The UV/Vis spectra was used to characterize the silver nanorods and its modified the L-Cys. Based on L-cysteine of SERS was high sensitivity and selectivity for Hg(Ⅱ) on condition that the ten kinds of metal ions carried on, but only when the single-peak at 1 040 cm-1 structure appeared after adding the Hg(Ⅱ). SERS sensor with L-cysteine assembled silver nanorods firmly captured the Hg(Ⅱ) through the S-Hg bond. It was valuable to get the molecular probe of the concentration, pH and temperature, in which the result showed the optimization when the density of L-cysteine was 1×10-3 mol·L-1 and pH was 7. It did not have a great effect on temperatures, but was down trend over 55 ℃. In order to protect the structure of L-Cysteine and form complexes rapidly, it was selected temperature about 45 ℃. Under the optimized conditions, a series of the concentration of mercury ions were measured, in which the result showed that the density of mercury ions between 0.01 and 5 μmol·L-1 can be analyzed because of a strong peak at 1 040 cm-1 with good linear relationships (correlation=0.990) with the detection limit of 1 nmol·L-1. Which had very excellent sensitivity and stability. When Hg2+ was tested in real water samples, the recovery was from 85%～103%. It establishes a good way to determine the trace Hg(Ⅱ)..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 117 (2018)
Quantitative Detection of Mixing Pesticide Residues on Navel Orange Based on Surface-Enhanced Raman Spectroscopy
LIU Yan-de, ZHANG Yu-xiang, and WANG Hai-yang
Pesticide residue in agricultural and sideline products has become a social problem. In order to solve the problem of pesticide residue in fruit production, the rapid detection of mixing pesticide residues with navel orange as carrier was explored by surface enhanced Raman spectroscopy (SERS). The organophosphorus pestPesticide residue in agricultural and sideline products has become a social problem. In order to solve the problem of pesticide residue in fruit production, the rapid detection of mixing pesticide residues with navel orange as carrier was explored by surface enhanced Raman spectroscopy (SERS). The organophosphorus pesticides phosmet and chlorpyrifos were the objects of study because they were used more in the field of pest control, and gold colloid was prepared to get the SERS of the organophosphorus pesticides. The SERS spectra of the mixing pesticide samples were collected, and the characteristic peaks of the pesticides could be used for qualitative analysis of the mixing pesticide. At the same time, the stoichiometric method could be used to establish the quantitative mathematical model of the mixing pesticide, and the combination of the optimal pretreatment method and the wavenumber could be selected by comparing the modeling results of the Raman spectra. In the Raman spectrum range of 200～2 300 cm-1, the partial least square (PLS) was used to build the model of the spectral data after the first derivatives data preprocessing. The results of the combined regression model were better, and it showed that the correlation coefficient (Rp) was 0.912, Root mean square error (RMSEP) was 3.601 mg·L-1. After spectral screening and comparison of the spectral results, it was found that the best model of the spectra was established by the PLS in the range of 200～620, 830～1 040 and 1 250～2 300 cm-1. The regression model had better effect, in which Rp was 0.909 and RMSEP was 3.338 mg·L-1. It had shown that the SERS technology could be used to qualitatively and quantitatively analyze the mixing pesticide residues on navel orange..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 123 (2018)
New Development of Metal Nanostructures Enhanced Fluorescence
WU Jiang-hong, CHENG Pei-hong, ZHANG Chi, WANG La, ZHAO Hong-xia, WANG Jing-rui, DING Zhi-qun, and BAO Ji-long
Surface plasmon (SP) is electron density oscillation wave that propagates at the metal-dielectric interface. When the oscillation frequency matches with the incident light frequency, surface plasmon resonance effects are induced. It leads to strong light extinction and field enhancement near the metal structures. SP reSurface plasmon (SP) is electron density oscillation wave that propagates at the metal-dielectric interface. When the oscillation frequency matches with the incident light frequency, surface plasmon resonance effects are induced. It leads to strong light extinction and field enhancement near the metal structures. SP resonance effect can be applied to SP imaging, SP waveguide, biology sensing and spectral enhancement. The research progress of metal nanostructure enhanced fluorescence was reviewed. Firstly, the mechanism of metal enhanced fluorescence and the factors influencing fluorescence enhancement were introduced. Then, the research progress in fluorescence enhancement using different metal structures was reviewed. Finally, some new applications of fluorescence enhancement such as food testing, environmental testing, imaging optics, optoelectronic devices, fluorescence upconversion were introduced..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 128 (2018)
Study Comparative Light Intensity of Laser Light Source-Online Fluorescence Spectrum Detection
Kariyemu·AIHAITI, Mirzat·MAIMAITI, and Arkin·IBURAIM
This paper Used laser light sources and xenon lamp light source of online fluorescence spectrometry to determine the optical content of rhodamine B, vitamin B2, fluorescein and fluorescein isothiocyanate, and compared the light intensity of laser light sources and xenon lamp light source. Methods:The optical concentratThis paper Used laser light sources and xenon lamp light source of online fluorescence spectrometry to determine the optical content of rhodamine B, vitamin B2, fluorescein and fluorescein isothiocyanate, and compared the light intensity of laser light sources and xenon lamp light source. Methods:The optical concentration of Rhodamine B, vitamin B2, fluorescein and different hydrogen sulfate fluorescein were equally 10 μg·mL-1; Integration time was 100 ms, and the average value was measured by three times detection. Maximum absorption wavelength determinated by online fluorescence spectrometry were respectively 580, 450, 488 and 510 nm; The maximum emission wavelength were respectively 594, 530, 525 and 524 nm. The maximum absorption wavelength detemineted by UV spectrophotometry were respectively 557, 441, 481 and 490 nm; Maximum emission wavelength detected by fluorescence method were respectively 586, 520, 519, 520 nm. By measuring medicine, we have found that the laser light source of the fluorescent light intensity is stronger than the xenon lamp light source of the fluorescent light intensity. The reason is not only related to the light source, and with the size of drug molecules conjugated system, large conjugated PI coplanar and rigid degree, the kinds of molecular substituents on the matrix, molecules of the external environment such as temperature, solvent, acid and alkali solution, such factors as the excitation light also can affect the fluorescent efficiency. Laser light sources and xenon lamp light source of the fluorescent light intensity size is rhodamine B> vitamin B2> fluorescein> fluorescein isothiocyanate in order. Laser light source online fluorescence spectrometry , to a certain extent, fill in the blank of online fluorescence spectrometer application in food, medicine, trace detection..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 134 (2018)
Influence of SO2-4/BO3-3 Doping on Properties of NaGd(MoO4)2∶Eu3+ Phosphors
WANG hua-yu, YAN Jing-hui, and ZOU Ming-qiang
NaGd(MoO4)2∶xEu3+(x=10%, 20%, 30%, 40%) and NaGd(MoO4)2∶7%Eu3+, ySO2-4/BO3-3 phosphors were prepared by hydrothermal method with sodium citrate as a surfactant. The crystal phase, morphology and luminescent properties of the prepared samples were characterized. The results showed that the structures of NaGd(MoO4)2∶xEu3NaGd(MoO4)2∶xEu3+(x=10%, 20%, 30%, 40%) and NaGd(MoO4)2∶7%Eu3+, ySO2-4/BO3-3 phosphors were prepared by hydrothermal method with sodium citrate as a surfactant. The crystal phase, morphology and luminescent properties of the prepared samples were characterized. The results showed that the structures of NaGd(MoO4)2∶xEu3+ and NaGd(MoO4)2∶7% Eu3+, ySO2-4/BO3-3 phosphors were tetragonal scheelite. The characteristic absorption peak of SO2-4/BO3-3 was found by infrared spectroscopy, indicating that SO2-4/BO3-3 was successfully incorporated into the matrix. The emission spectrum of NaGd(MoO4)2∶30%Eu3+ was the strongest. Besides, by studying the emission spectrum of NaGd(MoO4)2∶7%Eu3+, ySO2-4/BO3-3 phosphors, it can find that appropriate doping of SO2-4/BO3-3 can enhance the characteristic emission intensity of Eu3+. The addition of 10% SO2-4 or 10% BO3-3 can reduce the doping of Eu3+ by about 3%, which can save the doping amount of rare earth..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 139 (2018)
Synthesis of La2(MoO4)3∶Eu Magnetically Fluorescent Nanoparticles and Its Application for Latent Fingerprint Development
YU Ao-yang, YANG Rui-qin, and WANG Meng
In this study, fluorescent La2(MoO4)3∶Eu and magnetic Fe3O4 nanomaterials were synthesized by hydrothermal and coprecipitation, respectively. The size, morphology, crystal structure, and fluorescent property of as-synthesized nanomaterials were characterized by transmission electron microscopy (TEM), X-ray diffraction In this study, fluorescent La2(MoO4)3∶Eu and magnetic Fe3O4 nanomaterials were synthesized by hydrothermal and coprecipitation, respectively. The size, morphology, crystal structure, and fluorescent property of as-synthesized nanomaterials were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) spectroscopy, and fluorescence spectroscopy (FS). The La2(MoO4)3∶Eu fluorescent nanomaterials were flaky in shape, and the crystal structure was tetragonal La2(MoO4)3 phase. The La2(MoO4)3∶Eu fluorescent nanomaterials could emit strong red fluorescence under 254 nm ultraviolet(UV) excitation.While the magnetic Fe3O4 nanomaterials were spherical in shape with an average diameter of about 60 nm, and the crystal structure was cubic Fe3O4 phase. Subsequently, the above two nanomaterials were mixed together in a certain ratio to form the La2(MoO4)3∶Eu/Fe3O4 superparamagnetic fluorescent nanomaterials. The as-prepared La2(MoO4)3∶Eu/Fe3O4 nanomaterials were of sheet structure mixed with spherical particles in shape, which could emit red fluorescence weaker than pureLa2(MoO4)3∶Eu fluorescent nanomaterials under 254 nm ultraviolet excitation. However, the red fluorescence from La2(MoO4)3∶Eu/Fe3O4 nanomaterials could still meet the needs of the fingerprint development. Although the as-prepared nanomaterials and La2(MoO4)3∶Eu fluorescent nanomaterials have same effect in developing fingerprint on smooth object, the as-prepared nanomaterials could form a suitable fringe by using a magnetic applicator to prevent dust pollution and develop the detail features of fingerprint with bright red fluorescence stimulated by the excitation of 254 nm ultraviolet light. Finally, the as-prepared nanomaterials were applied to develop the fresh latent fingerprints on various smooth and rough substrates. The results showed that the latent fingerprints developed by our nanomaterials could appear the detailed features of friction ridges with a high contrast. In addition, the nanomaterials-based fingerprint development also possessed some other advantages, such as low background interference, high developing contrast, wide application range of substrates, and no powder dusting. The as-prepared fluorescent nanomaterials are superparamagnetic fluorescent nanomaterials. The performance of this powder is obviously better than non-magnetic fluorescent nanomaterials. Therefore, the as prepared superparamagnetic fluorescent nanomaterials have been proved to be an ideal material for latent fingerprint development, which have great potential in forensic applications..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 144 (2018)
Melon Seeds Variety Identification Based on Chlorophyll Fluorescence Spectrum and Reflectance Spectrum
LI Cui-ling, JIANG Kai, FENG Qing-chun, WANG Xiu, MENG Zhi-jun, WANG Song-lin, and GAO Yuan-yuan
Melon is popular with us for its high nutritional value, and there are many varieties of melons. Impurity of melon seed variety will cause harm to melon production. This research adopted chlorophyll fluorescence spectrum combined with reflectance spectrum to identify melon seeds variety. Seeds whose varieties were “Yi Melon is popular with us for its high nutritional value, and there are many varieties of melons. Impurity of melon seed variety will cause harm to melon production. This research adopted chlorophyll fluorescence spectrum combined with reflectance spectrum to identify melon seeds variety. Seeds whose varieties were “Yi Te Bai”, “Yi Te Jin”, “Jing Mi No.7”, “Jing Mi No.11”, “Yi Li Sha Bai” were used as research samples. A melon seeds variety identification system based on spectrum technology was developed, and it included an excitation light source unit, a spectral data acquisition unit and a data processing unit. This system was used to obtain fluorescence spectrums and reflectance spectrums of different varieties of melon seeds. First derivative (FD), Savitzky-Golay (SG), and FD associated with SG were utilized to preprocess spectral data respectively. Principal component analysis (PCA) method was adopted to reduce the dimensions of spectral data and extract principal components. This study adopted two different grouping methods to divided samples into training set and validation set according to the proportion of 3∶1, and Fisher discriminant analysis and Bayes discriminant analysis methods were used to establish discriminant models of melon seeds variety respectively. This study compared the discriminant effect of the model developed only using chlorophyll fluorescence spectral information with the discriminant effect of model developed based on chlorophyll fluorescence spectral information combined with reflectance spectral information. Results showed that discriminant model developed using chlorophyll fluorescence spectral information combined with reflectance spectral information generated better determination results than only using chlorophyll fluorescence spectral information, and the discriminant accuracies of validation set reached 98% in both Fisher discrimination analysis and Bayes discriminant analysis. Research results showed that chlorophyll fluorescence spectrum combined with reflectance spectrum technique was feasible for melon seeds variety identification..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 151 (2018)
A Fluorescence Spectroscopic Study of the Interaction between Trelagliptin Succinate and Bovin Serum Albumine and Its Analytical Application
GONG Ai-qin, JIN Dang-qin, and ZHU Xia-shi
In this paper the interaction between trelagliptin succinate (QGLT) and bovine serum albumin (BSA) was studied by fluorescence spectrometry. The factors affecting fluorescence quenching such as solution acidity and medium characteristics were optimized. The examination results of quenching mechanism showed that the fluIn this paper the interaction between trelagliptin succinate (QGLT) and bovine serum albumin (BSA) was studied by fluorescence spectrometry. The factors affecting fluorescence quenching such as solution acidity and medium characteristics were optimized. The examination results of quenching mechanism showed that the fluorescence intensity of BSA was quenched strongly by QGLT mainly through a static quenching procedure, the number of binding sites was 1, and the biding constants was 4.529×104L·mol－1 (298 k) or 2.958×104 L·mol－1 (303 k), respectively. The determination results of thermodynamic parameters show that the change of Gibbs free energy, enthalpy or entropy was negative, which clarified there was an automatic reaction happened between QGLT and BSA, and both hydrogen bonds and van der Waals force played a role in the binding of QGLT to BSA. It was also found in the examination that Lineweaver-Burk equation ［(F0－F)－1=2.711×10－4+3.51×10－3 cQGLT－1(cQGLT: 0.5～10.0 μg·mL-1)］ owned better linear relationship (r=0.998 9) with the detection limit of 0.13 μg·mL-1. The recovery experiment results showed that the method owed good accuracy(the recovery is 94.0%～97.5%) and the proposed method has been successfully applied to determine QGLT in QGLT tablet and human serum. The examination developed a new method to determine the content of QGLT..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 157 (2018)
Research on Fast Target Recognition Method Based on Spectrum Detection in Battlefield
CHENG Cheng, GAO Min, CHENG Xu-de, FANG Dan, and CHEN Yi-chao
In the modern battlefield, in order to improve the combat capability of the precision guided weapons, realizing effective recognition and precision strikes for targets in battlefield, in this paper, a new method of fast target recognition based on spectral fingerprint analysis is proposed, which combines the characteriIn the modern battlefield, in order to improve the combat capability of the precision guided weapons, realizing effective recognition and precision strikes for targets in battlefield, in this paper, a new method of fast target recognition based on spectral fingerprint analysis is proposed, which combines the characteristics of precision guided weapon seeker characteristics with the operational characteristics. Spectral detection technique is used to obtain the spectral fingerprints of the suspected target areas, and then the target characteristics are analyzed through the spectral fingerprints. Due to the time limit of the precision guided weapon in the actual combat, the process speed of target identification and processing must have good real-time performance. Based on this, we simplified the traditional spectrum detection processing program, and only on the range of the part was concerned with the spectral analysis, so that the amount of data was greatly reduced; When analyzing the spectrum information, the characteristic wavelength of the equipment was defined according to the classification of the weapon and equipment, and the characteristic information of the target was used to characterize a class of targets, which can help to improve the speed of target recognition. In this paper, firstly the influence of target recognition methods were expounded, which showed the necessity of this study; then the fast identification method based on spectrum detection was derived, which showed the feasibility of this study; at last, the proposed method of fast target recognition based on spectrum detection was verified by a series of experiments, which showed the superiority of this study..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 161 (2018)
Research on Pyrophoric Multi-Hole Activated Metal Spectral Radiation Characteristics
HUANG He-song, TONG Zhong-xiang, CHAI Shi-jie, MA Bang, and WANG Chao-zhe
The contact area between multi-hole activated metal and air greatly increases, because of the large number of holes in multi-hole activated metal. So the combustion of multi-hole activated metal is serious in the air, which causes the temperature rising rapidly. The combustion process is quite complex and belongs to soThe contact area between multi-hole activated metal and air greatly increases, because of the large number of holes in multi-hole activated metal. So the combustion of multi-hole activated metal is serious in the air, which causes the temperature rising rapidly. The combustion process is quite complex and belongs to solid combustion. To solve the combustion problem of multi-hole activated metal, magnesium was chosen as the activated metal in the paper. The combustion models were established to research the spectral radiation characteristics. Firstly, we established the relationship between total consumption of oxygen and residual mass of activated metal and studied the diffusion concentration of oxygen in activated metal hole. The relationship between temperature and time were obtained by solving the heat balance equations of active metal in the process of combustion. Secondly, the simulation results by calculation were compared with the experiment results which were obtained by thermal imager. The results demonstrated that the model calculated results consistent with experiment and the error was controlled within 10%. Finally, the burning rule and spectral radiation characteristics of activated metal were studied by the establishment of combustion models. So the problem that the spectral radiation intensity is difficult to be obtained by experiment at high altitude and velocity was solved, which decreased the experiment cost and time. The activated metal radiation intensity in the waveband of 1～3, 3～5 and 8～12 μm were compared at different time and get the condusion that the nain radiation intensity focuses on the waveband of 3～5 μm. The results demonstrated that: the maximal burning temperature increased firstly and then decreased with the increase of the velocity . It also decreased with the increase of the altitude; The temperature reached maximum at the speed of 30 m·s-1; Activated metal spectral radiation intensity reached maximum at the waveband between 2 to 6 μm. The models can be applied in studying other activated metal burning characteristics..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 166 (2018)
Predicting Soil Available Nitrogen with Field Spectra Corrected by Y-Gradient General Least Square Weighting
QI Hai-jun, Karnieli Arnon, and LI Shao-wen
Soil available nitrogen is supposed to be an important nutrient constituent for the growth and development of crops. In-situ field visible-near infrared (VIS-NIR, 350~2 500 nm) spectroscopic analysis is a rapid and non-destructive method that has the potential to predict nitrogen. Further, it is cost-effective method cSoil available nitrogen is supposed to be an important nutrient constituent for the growth and development of crops. In-situ field visible-near infrared (VIS-NIR, 350~2 500 nm) spectroscopic analysis is a rapid and non-destructive method that has the potential to predict nitrogen. Further, it is cost-effective method compared with traditional laboratory analysis and can be used to provide a database for the development of real-time soil nutrient sensors. However, prediction accuracy was greatly reduced due to unexpected environmental factors under field condition. In the current research, field work contained 76 samples from two sites located in the center and north parts of Israel. Y-gradient general least squares weighting (Y-GLSW) algorithm was investigated to filtering correct the field VIS-NIR spectra for improving the prediction ability of nitrogen. Firstly, Savitzky-Golay (SG) smoothing algorithm, first derivative transformation and standard normal variate were sequentially conducted to preprocess and transform the raw field spectra (RS). Then, a filtering model was established based on the Y-GLSW algorithm to correct the preprocessed and transformed spectra (PPT). After that, partial least square - regression (PLS-R) algorithm was applied to build regression models with RS, PPT, and Y-GLSW corrected spectra, respectively. As a result, the regression model based on RS was proved to be unfeasible. The ratio of performance to deviation (RPD) and the ratio between interpretable sum squared deviation and real sum squared deviation (SSR/SST) of the test set of the PPT-based regression model were found to be 1.41 and 0.57, respectively. The results of Y-GLSW-based regression model were RPD = 2.07 and SSR/SST=0.69 that significantly increased by 46.81% and 21.05% compared with PPT-based regression model. The results indicated that Y-GLSW was suitable to remove some unexpected variations (like the effect of environmental factors) of field spectra and improved the prediction accuracy and explanation ability of PLS-R model for predicting nitrogen..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 171 (2018)
Measurement of H2O Spectroscopic Parameters near 1.39 μm and Application in Combustion Kinetics
GOU Yu-dan, LU Peng-fei, HE Jiu-ning, ZHANG Chang-hua, LI Ping, and LI Xiang-yuan
The accuracy of absorption spectral parameters is very important for the on-line measurement of combustion gas based on tunable diode laser absorption spectroscopy. In order to apply the spectroscopic parameters in infrared region in detecting the H2O concentration, it is necessary to validate these parameters experimeThe accuracy of absorption spectral parameters is very important for the on-line measurement of combustion gas based on tunable diode laser absorption spectroscopy. In order to apply the spectroscopic parameters in infrared region in detecting the H2O concentration, it is necessary to validate these parameters experimentally, especially the Ar-broadening coefficient, which is crucial to elementary reaction in combustion and validation mechanism. By using a distributed feed back diode laser as light source and combining with spectral parameters measurement system, four spectral lines of H2O around 1.39 μm were collected. The line intensity, self-broadening and N2-broadening coefficient were obtained. The results agreed well with those in HITRAN database and literature. Moreover, the Ar-broadening coefficient was acquired systematically for the first time. By using current measured spectra parameters, the time-history of H2O concentration from H2/O2/Ar combustion behind high temperature reflected shock waves was obtained and corresponding combustion kinetic mechanisms were validated. The results in this work will provide reliable database for the measurement of H2O concentration from the combustion process of hydrocarbon fuels, as well as the validation of corresponding combustion kinetics research..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 176 (2018)
Black Soil Organic Matter Content Estimation Using Hybrid Selection Method Based on RF and GABPSO
MA Yue, JIANG Qi-gang, MENG Zhi-guo, and LIU Hua-xin
To solve the problem of high-dimensional variables and characteristic wavelengths selection on soil organic matter content estimation using hyperspectral data, a hybrid feature selection method that combined random forest and self-adaptive searching method was proposed. In this hybrid method, random forest was employedTo solve the problem of high-dimensional variables and characteristic wavelengths selection on soil organic matter content estimation using hyperspectral data, a hybrid feature selection method that combined random forest and self-adaptive searching method was proposed. In this hybrid method, random forest was employed to select spectral variables as the preliminary optimal dataset, which had great importance in the modeling process. The wrapper approach which combined genetic algorithm and binary particle swarm optimization was used as the self-adaptive searching algorithm to further search variables in the preliminary dataset. As for the prediction model, random forest was picked on because of the strong robustness and the excellent performance of dealing with high-dimensional variables. In this paper, the soil samples collected in the typical black soil region were used as the research object, and the Vis-NIR spectral data of the soil obtained from ASD spectrometer and the organic matter content through chemical analysis were used as the data sources. Following reflectance transformation and spectral resampling, the proposed hybrid selection method was employed to extract the characteristic spectral regions that were used as the input data for random forest. The prediction accuracy was compared with the results from random forest algorithm with the spectral datasets which were respectively extracted by no-selected method, only random forest method and only self-adaptive searching method. The results showed that using random forest model with the characteristic wavelengths extracted by proposed method obtained the highest predicted accuracy, in which the R2, RMSE and the RPD were 0.838, 0.54% and 2.534, respectively. Moreover, the proposed method was more efficient to selected features than other approaches. It can be concluded that the hybrid feature selection method and random forest algorithm can be effectively applied to black soil organic matter content estimation using hyperspectral data and it also provides a reference for solving the problem of variables selection and modeling on other types of soil organic matter content estimation..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 181 (2018)
Influence of Algae Blooms on DOM Characteristic in Water Bodies in Urban Landscape River
LI An-ding, ZHANG Yan, ZHOU Bei-hai, and LU Xue-qiang
In urban landscape rivers, algal bloom caused by excess nutrients broke out regularly in summer due to the acceptance of wastewater from different sources. The characteristics of DOM in the river water were changed because of the broken out of the algae bloom, and thus the migration and transformation of pollutants, whIn urban landscape rivers, algal bloom caused by excess nutrients broke out regularly in summer due to the acceptance of wastewater from different sources. The characteristics of DOM in the river water were changed because of the broken out of the algae bloom, and thus the migration and transformation of pollutants, which affected by DOM in the river water, was affected as well. In this study, the water samples before and after the algal blooms in the main stream of the Haihe River were collected to study the influence of outbreak of algae blooms on DOM in water bodies in urban landscape river. The results showed that the content of DOM in the river water increased from 26.47 to 38.20 mg·L-1. The contents of TN, NH+4-N and TON in the river water were 3.1 times, 2.5 times and 4.2 times higher than those before the algal bloom broke out, respectively, while, the contents of TP and NO-3- remained stable. C/N ratio decreased from 18.51 to 6.39 while N/P ratio increased from 5.69 to 20.10. The source of DOM changed from terrestrial source mainly to aquatic source mainly and the water also showed a gradual trend to phosphorus limit. Three-dimensional fluorescence spectra showed that the composition of DOM changed from the source of complex organic matter to the source of algae organic matter. The results of UV absorbance indicated that the molecular structure of DOM was changed to be more complex. However, the content of humus-liked in water decreased while the content of protein-liked increased. Ultrafiltration experiments were also conducted to study the molecular weight of DOM before and after algae blooms. It was found that DOM with small molecular weight had the dominates, in which DOM with molecular weight less than 10 kD accounted for more than 80% of the total DOM. With the increase of molecular weight, the intensity of all peaks of three-dimensional fluorescence spectra showed an increasing trend and the UV absorbance also indicated that the high molecular weight DOM might contain more aromatic compounds. The results suggested that the role of DOM should be paid attention to the eutrophication in urban landscape river water. Especially when external pollutants are controlled, the contribution of DOM degradation to eutrophication should be fully considered..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 188 (2018)
Research on the Online Test of Diesel NOx Emission by TDLAS
YUAN Zhi-guo, YANG Xiao-tao, XIE Wen-qiang, and LI Xue-min
NOx is the most harmful component for ecological environment in diesel engine emission. As global environmental problem becomes increasingly serious, the NOx emission of diesel engine has been concerned widely. With a variety of emission regulations legalized, this not only presents new demands for NOx emissions of dieNOx is the most harmful component for ecological environment in diesel engine emission. As global environmental problem becomes increasingly serious, the NOx emission of diesel engine has been concerned widely. With a variety of emission regulations legalized, this not only presents new demands for NOx emissions of diesel engine but also puts forward higher requirements for test method. Feasible test methods usually are the methods of sampling and analysis, which need a long sampling time and can’t achieve online measure of emission. The online measure of diesel engine emission is not only to the benefit of supervising but also provides data support for optimizing combustion process and optimizing control strategy for diesel engine. Optical detection technique serves as a new detection method. As one of it, the tunable diode laser absorption spectroscopy has been widely applied in other areas because of simple experimental principle and fast response speed. In order to verify the feasibility of this method in diesel engine NOx emissions testing, experimental team researched on the online test of diesel NOx emission by TDLAS. Aiming at the main component of NOx, two interband cascade lasers whose tunable wavelengths were 5 262~5 265 and 6 136~6 142 nm were selected as detecting light source for respectively testing NO and NO2. Thorlabs PDA10JT type thermal detectors were chosen for collecting optical signal. The diesel engine of D4114B by the direct detection was researched and the test result with the result of AVL emission analyzer was compared. The measure error is less than 5％. In addition, experimental team conducted NOx transient emission measurement of a diesel variable conditions with the high time resolution of TDLAS and obtained a reasonable changed consequence of NOx emissions. Thus, appling TDLAS technique has important significance for transient emission characteristics of diesel engine..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 194 (2018)
Non-Destructive Identification of Mineral Pigments in Ancient Murals by Visible Spectroscopy
LI Jun-feng, and WAN Xiao-xia
Regarding to the fact that sampling analysis techniques compromise the integrity of the invaluable and nonrenewable cultural relics, the non-invasive identification method, based on visible spectroscopy, was proposed to identified the chemical composition and particle size information of the pigment used ancient muralsRegarding to the fact that sampling analysis techniques compromise the integrity of the invaluable and nonrenewable cultural relics, the non-invasive identification method, based on visible spectroscopy, was proposed to identified the chemical composition and particle size information of the pigment used ancient murals. A non-contact acquisition platform was established to measure the visible spectrum of the ancient murals. A visible spectral database of the pigment was developed as the reference. After the analysis of the spectrum in the database, the non-invasive identification process and method were constructed based on visible spectroscopy to identify the chemical composition and particle size information of the pigment used ancient murals. First, the geometric feature of the visible spectrum was extracted to construct the feature space for chemical composition identification, and then the amplitude feature of the visible spectrum was integrated and fitted with the mean particle size for particle identification. The method was tested using the murals in Mogao Grottoes..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 200 (2018)
Response Characteristics Analysis of Different Vegetation Indices to Leaf Area Index of Rice
CHANG Hao-xue, CAI Xiao-bin, CHEN Xiao-ling, and SUN Kun
Leaf area index (LAI), the most frequently used parameter for monitoring agricultural ecology, could be utilized to provide scientific basis for crop disease, growth and carbon cycle monitoring as well as yield estimation. Vegetation indices (VIs), which can be employed to indicate LAI, are important data sources for sLeaf area index (LAI), the most frequently used parameter for monitoring agricultural ecology, could be utilized to provide scientific basis for crop disease, growth and carbon cycle monitoring as well as yield estimation. Vegetation indices (VIs), which can be employed to indicate LAI, are important data sources for satellite-based LAI production. And the most widely used one is Normalized Difference Vegetation Index (NDVI). Several standard satellite LAI products such as MODIS use NDVI as an input. However, the saturation characteristics of NDVI would introduce errors in the production of LAI. To find a possible optimized VI to derive the LAI of rice, 28 sets of spectral observations and corresponding LAI data were collected in the sample fields of Jiangxi Province. Four commonly used VIs including NDVI, Enhanced Vegetation Index (EVI), Soil Adjusted Vegetation Index (SAVI) and Modified Soil-Adjusted Vegetation Index (MSAVI) were extracted based on the in suit rice spectra. The response performance of the ground-based VIs to concurrent LAI measurements was assessed in this study. The linear regression results showed that the other three VIs had better adaptability than NDVI (R2=0.38), while EVI had the best performance (R2=0.82). MSAVI (R2=0.744) and SAVI (R2=0.751 1) also showed a better performance than NDVI. To continue, the differences between the results of ground-based model and the lookup table of MODIS LAI backup algorithm were compared. The MODIS LAI backup algorithm was derived from the empirical relationship between NDVI and LAI based on eight coarse biomass types. For biomass 1, it contained cereal and grass, and rice belonged to this category. In this paper, the lookup table of biomass 1 based on MODIS LAI backup algorithm was validated using the in situ LAI and spectral observations. The mean predict error of the algorithm was more than 3.2; and mean relative tolerance was up to 530%. This means large error will be introduced in rice LAI monitoring of this area if we use MODIS LAI backup algorithm. The low accuracy of MODIS backup algorithm may be caused by the coarse biomass classification system. In fact, different vegetation types included in biomass 1 had very significant difference in their canopy characteristics. Mixing them all in one class would result in an unacceptable errors to the LAI inversion for a specified crop type such as rice. The different saturation ranges of NDVI to inverse the LAI were also considered. The NDVI values kept unchanged with the increase of LAI when LAI was greater than 4 in the MODIS backup algorithm. Nevertheless, for the regression based on the rice field measured LAI and spectral observations, the saturation domain of NDVI was reached when LAI was larger than 2. After that, the accuracy comparison of the four ground-based VI models was implemented using root mean square error. The results showed that the mean predict error for NDVI model was 1.019 and only 0.55 for EVI model, which was only 1/6 of MODIS backup algorithm and 1/2 of NDVI model. Compared with the other three VIs, an addition blue band was utilized in the calculation of EVI to attenuate the aerosol impact on red band. This may be one of the possible reasons to explain the better performance of EVI. Therefore, an algorithm based on EVI could be developed as an alternative approach to improve the accuracy of LAI inversion..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 205 (2018)
Spectra Recognition of Corn Pollution Degree under Copper and Lead Ion Stress
GUO Hui, YANG Ke-ming, ZHANG Wen-wen, LIU Cong, and XIA Tian
The effect of heavy metals copper ion (Cu2+) and lead ion (Pb2+) on corn leaf spectra is weak, hidden and difficult to be detected. The corn pot experiment of different concentrations of Cu2+, Pb2+ stress is set. Corn leaf spectra, leaf Cu2+, Pb2+ content, and chlorophyll relative content were measured. The corn leaf sThe effect of heavy metals copper ion (Cu2+) and lead ion (Pb2+) on corn leaf spectra is weak, hidden and difficult to be detected. The corn pot experiment of different concentrations of Cu2+, Pb2+ stress is set. Corn leaf spectra, leaf Cu2+, Pb2+ content, and chlorophyll relative content were measured. The corn leaf spectra characteristic due to Cu2+, Pb2+ pollution stress was also analyzed, and then 480～670 and 670～750 nm bands were selected to be studied. The index of spectra derivative difference entropy and the first three times harmonic amplitudes (c1, c2 and c3) was defined, and then leaf spectra faint change was detected by use of the index. In the end, it was concluded that in 480～670 and 670～750 nm bands, corn leaf had the greater concentration of heavy metal ions and the greater of its corresponding spectra derivative difference entropy. In 480～670 nm bands, the harmonic amplitudes c1 and c2 can be used to identify the Cu2+, Pb2+ pollution degree; In the 670～750 nm bands, the harmonic amplitudes c1, c2 and c3 can be used to identify Cu2+ pollution level, and c2 can identify the Pb2+ pollution degree. The larger amplitude value meaned more serious pollution stress in 480～670 and 670～750 nm bands. The index of spectra differential difference entropy and harmonic amplitudes (c1, c2 and c3) can be used as identification corn pollution degree under Cu2+, Pb2+ stress. The method based on spectra and frequencey domain to identify corn pollution degree under Cu2+, Pb2+ stress was feasible. The index of spectra differential difference entropy and harmonic amplitudes (c1, c2 and c3) can be more robust and reliable in the detection and identification spectra weak differences of corn leaf affected by Cu2+, Pb2+, and the result has certain practical application value in identifying vegetation pollution degree under heavy metal on base of hyperspectral data..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 212 (2018)
Study on Distribution of Phosphorus Fractions and Adsorption-Desorption Characteristics in Surface Sediments of the Yellow River by Molybdenum Antimony Spectrophotometry
GUO Chen-hui, LI He-xiang, FANG Fang, JI Yu-shan, XING Yun-xin, FAN Yi-bing, and LIU Ying
In order to study the distribution on phosphorus fractions and adsorption-desorption characteristics in surface sediments from Gansu, Ningxia and Inner Mongolia sections of the Yellow River, the methods of standards measurements and testing (SMT) and molybdenum antimony spectrophotometry were chosen to extract phosphorIn order to study the distribution on phosphorus fractions and adsorption-desorption characteristics in surface sediments from Gansu, Ningxia and Inner Mongolia sections of the Yellow River, the methods of standards measurements and testing (SMT) and molybdenum antimony spectrophotometry were chosen to extract phosphorus fractions and measure contents, respectively. The assays of adsorption-desorption characteristics on phosphorus were carried simultaneously. The results were as follows: Compared with the different evaluation criteria, the contents of TP in all sampling sites were in different levels of pollution.Especially at S12 sampling site, a high release risk of phosphorus was existed. There were better positive correlations among TP, IP and HCl-P as well as between OP and NaOH-P. Composition and physicochemical properties of surface sediments had effects on various fractions of phosphorus, OP and NaOH-P were likely to have the same sources of pollution with As, Ni, Co and Pb. The adsorption-desorption processes of phosphorus were in accord with the pseudo-second-order kinetics,which suggested the processes were mainly controlled by chemistry. The isothermal adsorption of phosphorus was also in accord with the Langmuir equation, and the adsorbent contents of phosphorus were incremental with the rise of temperature. When the concentrations of KCl in aqueous phase were less than 0.02 mol·L-1, the adsorption process of phosphorus was predominant; conversely, the desorption process was dominant. The increase of water-soil ratios improved the adsorptive capacity of phosphorus. The rise of temperature and intensity of disturbance would improve desorption of phosphorus. The study revealed the distribution of phosphorus fractions and adsorption-desorption characteristics in surface sediments, providing bases for treatment of water environment and regulation of phosphorus load in Gansu, Ningxia and Inner Mongolia sections of the Yellow River..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 218 (2018)
Atmospheric Correction of Airborne Hyperspectral Image Based on Fruit Fly-Powell Optimization Algorithm
PAN Cen-cen, YAN Qing-wu, DING Jian-wei, ZHANG Qian-qian, and TAN Kun
Atmospheric correction of airborne hyperspectral is the basis of quantitative retrieval of hyperspectral remote sensing. However, the comparison analysis of aerial and field synchronous data was relatively rare, and it was mainly studied in this paper that the different atmospheric correction methods are compared with Atmospheric correction of airborne hyperspectral is the basis of quantitative retrieval of hyperspectral remote sensing. However, the comparison analysis of aerial and field synchronous data was relatively rare, and it was mainly studied in this paper that the different atmospheric correction methods are compared with the fieldwork spectral of Hyspex hyperspectral remote sensing data. Based on the existing several atmospheric correction methods, a novel atmospheric correction method was proposed in this paper: Firstly, we used Fruit fly-Powell optimization algorithm, spectral performance parameters, that is, shift at the center wavelength (σλ) and Full Width of Half Maximum (σFWHM) are retrieved, so the original spectral is recalibrated. We used the spectral of recalibration, and MODerate spectral resolution atmospheric TRANsmittance algorithm (MODTRAN) was applied for atmospheric correction. Ground synchronous measured reflectance data of five types of typical objects was used, and it was then evaluated the accuracy of the method proposed in this paper and other five generally used atmospheric correction methods: QUick Atmospheric Correction (QUAC), Empirical Line Correction (ELC), Second Simulation of the Satellite Signal in the Solar Spectrum(6S) atmospheric correction, Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) correction and MODTRAN atmospheric correction. Determination coefficient (R2) and root mean square error (RMSE) were introduced to evaluate the accuracy of the atmospheric correction results. Accuracy evaluation results showed that the proposed MODTRAN optimized based on Fruit fly-Powell algorithm in this paper was the best, with R2 above 80%, and RMSE within 15%; the results of MODTRAN, FLAASH and 6S atmospheric correction methods were closer to the proposed new method, and also the accuracy of the three atmospheric correction results were relatively stable, with R2 above 70%, RMSE around 20%. Moreover, QUAC and ELC methods were instable. It is concluded that Fruit fly-Powell algorithm is effective and feasible to estimate σλ and σFWHM, and thus the accuracy of the novel atmospheric correction method is better than the existing various atmospheric correction methods..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 224 (2018)
Hyperspectral Model Transfer for Citrus Canker Detection Based on Direct Standardization Algorithm
WENG Hai-yong, CEN Hai-yan, and HE Yong
There is existence of poor universality and low prediction precision in citrus canker hyperspectral models in previous research. It is necessary to investigate an approach to improve the robustness of hyperspetral model transfer between different instruments which proposed to improve the robustness of the calibration mThere is existence of poor universality and low prediction precision in citrus canker hyperspectral models in previous research. It is necessary to investigate an approach to improve the robustness of hyperspetral model transfer between different instruments which proposed to improve the robustness of the calibration model. Hyperspectral images of two different varieties including Navel Orange 52andCaraCarawere acquired using a laboratory hyperspectral imaging system (System 1, S1) and a portable hyperspectral imaging system (System 2, S2). The discriminant models for the citrus canker detection were developed based on the images from S1 and S2, respectively, and different pretreatment and classification methods were also investigated. Meanwhile, direct standardization (DS) algorithm was used to calibrate hyperspectral images collected by S2 which was considered as the slave while S1 as the master, and the performance of the discriminant model were evaluated before and after the model transfer. It was shown that the best discriminant results were achieved by the extreme learning machine (ELM) combined with the second-order derivative with the classification accuracies of 97.5% by S1 and 98.3% by S2, respectively. By using DS, the classification accuracy increased from 38.1% to 86.2% after the model transfer. It is demonstrated that the DS algorithm is useful for the calibration model transfer between different instruments, which would be helpful for developing a robust method for the citrus canker detection..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 235 (2018)
Study on Farmland Soil Fertility Model Based on Multi-Angle Polarized Hyper-Spectrum
WANG Ling-zhi, HAN Yang, and PAN Qian
With the introduction of the concept precision agriculture, acquiring information quickly and precisely has become the focus researchers. Polarization remote sensing can improve the accuracy of exploring and identifying features without causing damage, because it colligates multi-angle remote sensing, hyper-spectral reWith the introduction of the concept precision agriculture, acquiring information quickly and precisely has become the focus researchers. Polarization remote sensing can improve the accuracy of exploring and identifying features without causing damage, because it colligates multi-angle remote sensing, hyper-spectral remote sensing and microwave remote sensing. Previous researches are mainly based on single standard of soil fertility. This study explores the relationship between Integrated Fertility Index (IFI) and soil spectrum curve under the best observation conditions through measuring the spectrum curves in different conditions of typical farmland soil in Jilin Province. The study shows that incidence angles, relative azimuth angles and polarized states will affect soil spectrum curve under certain circumstances In fact, the design of the most workable remote sensing to observe soil fertility for this purposecan be realized by equipment. In this way, soil reflection was mathematically manipulated into first derivative reflectance spectra and inverse-log spectra, then established soil fertility model on ground of characteristic bands. The study shows the negative correlation between soil fertility and reflectance, positive correlation between soil fertility and absorptivity of spectrum, but the correlation between soil fertility and reflectance of spectrum in first differential is uncertain. When using reflectance of spectrum and first differential reflectance of spectrum and absorbance indexes to calculate soil fertility, it has been found that the quadratic function of reflectance of spectrum and fertility fits properly , with determination coefficient reaching 0.876 and 0.867 at 560 and 860 nm respectively..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 240 (2018)
Application of Hyperspectral Technology for Detecting Adulterated Whole Egg Powder
LIU Ping, and MA Mei-hu
Traditional analysis of food adulteration is more concentrated in the detection of specific known or suspected adulterants which may exist. However, due to the variety of adulteration and the emergence of new adulterants, the traditional detection methods have limitations. Currently, as an ideal substitute for fresh egTraditional analysis of food adulteration is more concentrated in the detection of specific known or suspected adulterants which may exist. However, due to the variety of adulteration and the emergence of new adulterants, the traditional detection methods have limitations. Currently, as an ideal substitute for fresh egg, the adulteration of egg powder is serious, but the problem is rarely studied both at home and abroad. In order to explore a rapid detection method of whole egg powder adulteration, this study attempted to use hyperspectral technology green and nondestructive in its advantages to detect the feasibility of whole egg powder with several adulterants. Different brands of egg powder were collected from different area and the common adulterants (starch, soy isolate protein, maltodextrin and mixture) were added in in proportion. After spectral acquisition, the region of interest (ROI) was extracted by ENVI and the mean spectra were extracted. Firstly, the support vector machines (SVM) models were founded to identify the adulteration and the Partial least squares (PLSR) model was used to establish the relationship between the full bands and adulteration concentration. The results showed that the correctness of the SVM model based on RBF kernel function was more than 90%, and the correlation coefficient between the actual value and the prediction value of the adulteration model based on PLSR was higher than 0.90. In order to simplify the model, the regression coefficient method (RC) and the successive projections algorithm (SPA) were used to extract the characteristic wavelengths, and the RC-PLSR model and SPA-PLSR were established according to the spectral data at the characteristic wavelength. The results showed that the simplified models still have good performance, indicating that the hyperspectral technique to detect adulteration of whole egg powder is feasible..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 246 (2018)
Tomato Leaf Liriomyza Sativae Blanchard Pest Detection Based on Hyperspectral Technology
LI Cui-ling, JIANG Kai, MA Wei, WANG Xiu, MENG Zhi-jun, ZHAO Xue-guan, and SONG Jian
Tomato yield and farmers’ economic benefits will decrease when insect pest occurs in the growth of tomato plants. This study used hyperspectral technology combined with chemometrics methods to realize fast identification of tomato leaf LiriomyzaSativae Blanchard pest. A simple hyperspectral imaging system was developedTomato yield and farmers’ economic benefits will decrease when insect pest occurs in the growth of tomato plants. This study used hyperspectral technology combined with chemometrics methods to realize fast identification of tomato leaf LiriomyzaSativae Blanchard pest. A simple hyperspectral imaging system was developed, including a light source unit, and hyperspectral image acquisition unit and a data processing unit, and hyperspectral images of tomato leaves were collected through this system. Hyperspectral images were calibrated and spectral information was extracted from each image. Spectral angle mapping (SAM) analysis method and spectrum red edge parameters discriminant analysis (DA) method were adopted to identify tomato leaf Liriomyza Sativae Blanchard pest respectively. In the SAM analysis, normalization algorithm was utilized to preprocess hyperspectral data so as to eliminate redundant information in hyperspectral data and increase the differences between samples. Discriminant effects of tomato leaf pest were compared when different reflective spectrums of tomato leaf samples were used as test spectrums. It was found that when regarding the average reflectance spectrum of 100 tomato leaves infected by Liriomyzasativae Blanchard pest as the test spectrum, the overall recognition accuracy was higher, reaching to 96.5%. In spectrum red edge parameters discriminant analysis, 6 kinds of red edge information that red edge position, red edge amplitude, minimum amplitude, red edge area, location of minimum chlorophyll absorption, and the ratio of red edge amplitude to minimum amplitude were extracted from tomato leaves’ spectral data. Discriminant analysis method was used to develop discriminant model of tomato leaf LiriomyzaSativae Blanchard pest, discriminant effects of distance discriminant analysis, Fisher discriminant analysis, and Bayes discriminant analysis were compared. Comparison results indicated that Fisher discriminant analysis generated the best discriminant effect. The discriminant accuracy was 96.0% for validation set, while distance discriminant analysis produced the worst discriminant effect, with 88.0% discriminant accuracy. Research results showed that using hyperspectral technology to identify Liriomyza sativae Blanchard pest was feasible..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 253 (2018)
Reduction of CO2 Effect on Unburned Carbon Measurement in Fly Ash Using LIBS
NAN Wei-gang, Yoshihiro Deguchi, WANG Huan-ran, LIU Ren-wei, Akihiro Ikutomo, and WANG Zhen-zhen
In thermal power plant, the measurement of unburned carbon in fly ash becomes increasingly important because unburned carbon contents are usually important factors for the operation of power plants and it can be an indicator of the combustion conditions Thus, the goal of combustion optimization and efficiency improvemeIn thermal power plant, the measurement of unburned carbon in fly ash becomes increasingly important because unburned carbon contents are usually important factors for the operation of power plants and it can be an indicator of the combustion conditions Thus, the goal of combustion optimization and efficiency improvement can be achieved. More specifically, the unburned carbon concentration in fly ash reflects the combustion efficiency of the power generator set. The combustion efficiency decreases with increasing of unburned carbon level in fly ash, which means a loss of fuel energy. Owing to the non-contact, fast response, high sensitivity and online measurement features, LIBS was used to measure the quantitative contents in fly ash in this research. But the carbon emission intensity changed with the fluctuant amount of CO2 in flue gas. In this study, dual-channel spectrometer was utilized to analyze the elemental spectra of C, Si, Mg, Fe, Ca, Al and so on, and the neighboring elemental spectra, such as C and Fe, can be recognized in the high resolution channel, which means sufficient fly ash spectrum information can be gained with enough measurement accuracy at the same time. Cyclone was designed and two-stage cyclone system was proposed into the system of LIBS measurement for unburned carbon contents in fly ash. Fly ash particles from the feeder flow through the two-stage cyclone and went into the chamber. The laser shot on the fly ash through the lens. Plasma was acquired and then recorded and analyzed by spectrometer and ICCD camera. The two-stage cyclone system was proven to be detectable for the unburned carbon in fly ash. In addition, two-stage cyclone system can be able to separate and collect fly ash particles from flow gas to reduce the influence of CO2 in fly ash particle flow, thus, exact data can be got to guide the operation of the thermal power plant, which provide more benefits to the engineering applications of LIBS..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 258 (2018)
The Research for Quantitative Analysis of Iron in Myanmar Jades Using Laser Induced Breakdown Spectroscopy
WANG Ya-jun, YUAN Xin-qiang, SHI Bin, SHI Mei-yu, ZHANG Qian, and CHEN Tao
Using laser-induced breakdown spectroscopy (LIBS), quantitative analysis of iron(Fe)in Myanmar jades has been studied in this work. Ion’s LIBS spectrum at 275.57 nm was chosen for quantitative spectral analysis, and Silicon’s LIBS spectrum at 288.17 nm was selected as internal standard line. Twelve pieces of jade from Using laser-induced breakdown spectroscopy (LIBS), quantitative analysis of iron(Fe)in Myanmar jades has been studied in this work. Ion’s LIBS spectrum at 275.57 nm was chosen for quantitative spectral analysis, and Silicon’s LIBS spectrum at 288.17 nm was selected as internal standard line. Twelve pieces of jade from Myanmar were selected as specimens. Nine of them were applied to construct the spectral calibration curves of iron with traditional method and internal standard method, and the content of iron in another three specimens selected as test samples was practically predicted. The experimental results show that the relative standard deviation of the intensity of iron is between 1.4% and 8.3%, while the fitting correlation (R2) of calibration curve is 0.979, and the maximum relative error of test samples is 10.6% when traditional method is used. While the internal standard method was used, the relative standard deviation of the intensity ratio of iron and silicon is between 0.9% and 5.7%, while the fitting correlation (R2) of calibration curve is 0.989, and the relative error of test samples reduces to under 7%. The analyzed results indicate that using LIBS coupled with internal standard method is much better to quantitatively analyze the content of iron in Myanmar jades compared with applying traditional method, as internal standard method can reduce the relative error of measurement..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 263 (2018)
The Qualitative and Quantitative Detection of Potassium Alum in Sweet Potato Starch Based on Terahestz Time-Domain Spectroscopy
GUAN Ai-hong, LI Zhi, and GE Hong-yi
The Terahertz spectra of sweet potato starch, potassium alum and their compounds are measured in 0.3~2.0 THz using Terahertz time - domain spectroscopy ( THz-TDS) system. The refractive index and absorption coefficient spectrum are calculated. Experimental results show that potassium alum has distinct absorption featurThe Terahertz spectra of sweet potato starch, potassium alum and their compounds are measured in 0.3~2.0 THz using Terahertz time - domain spectroscopy ( THz-TDS) system. The refractive index and absorption coefficient spectrum are calculated. Experimental results show that potassium alum has distinct absorption features in the THz region, which can be used as fingerprint for the material identification. in addition, The Terahertz spectra of sweet potato starch doped with different percentages potassium alum are measured. The refractive index and absorption coefficient spectrum which are calculated indicate that the higher proportion of Potassium alum is, the larger the absorption coefficient in the compounds is. So is the refractive index. The results indicate that THz-TDS can be used to qualitative and quantitative detection ofpotassium alum in sweet potato starch..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 267 (2018)
Quantitative Analysis of P in Fertilizer by Laser-Induced Breakdown Spectroscopy with Multivariate Nonlinear Method
LIAO Su-yin, WU Xian-liang, LI Gui-hua, WEI Min, and ZHANG Mei
The quantitative analysis of phosphorus in fertilizer was investigated by laser-induced breakdown spectroscopy (LIBS) in this paper. The atomic spectral lines of 255.3 and 844.6 nm for phosphorus and oxygen, respectively, were determined as the optimized line by analyzing the excitation energy, transition probability aThe quantitative analysis of phosphorus in fertilizer was investigated by laser-induced breakdown spectroscopy (LIBS) in this paper. The atomic spectral lines of 255.3 and 844.6 nm for phosphorus and oxygen, respectively, were determined as the optimized line by analyzing the excitation energy, transition probability and interference elements. Eighteen samples were analyzed and fourteen of them were tested to construct the calibration curve of measured concentration of phosphorus, while the linear fitting degree of the calibration curve was 0.83. It should utilize more information of LIBS spectra to construct the multivariate nonlinear regression method, which can improve the measurement accuracy of LIBS. Compared with the calibration method, the correlation coefficient of the prediction concentration of LIBS with reference concentration was 0.98, and the relative measured error was greatly reduced, only in the range of 0.38%～1.70%. It is shown that LIBS has the potential for rapid analysis of phosphorus in fertilizer..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 271 (2018)
Influence of Background Deduction and Intensity Correction on Spectral Parameters of Laser Induced Plasma
WANG Jing-ge, LI Xin-zhong, LI He-he, WANG Hui, ZHANG Li-ping, YIN Chuan-lei, and TANG Miao-miao
Laser-Induced Breakdown Spectroscopy (LIBS) has been widely used in more and more fields as a method for qualitative or quantitative analysisas a result of its unique advantages, such as no sample preparation, fast analysis speed, multi-element detection simultaneously, remote analysis, etc.. The theoretical basis of tLaser-Induced Breakdown Spectroscopy (LIBS) has been widely used in more and more fields as a method for qualitative or quantitative analysisas a result of its unique advantages, such as no sample preparation, fast analysis speed, multi-element detection simultaneously, remote analysis, etc.. The theoretical basis of this technique is laser-induced plasma. Accurate measurement of spectral parameters of the plasma (such as spectral line intensity and plasma temperature) is a prerequisite for qualitative or quantitative analysis by LIBS. However, due to the inherent performance of the instrument in practical experiments, the distortion of the acquired spectral signal can be caused, which limits the precise measurement or calculation of the plasma spectral parameters. In order to overcome the impact of instrument performance, the influences of the inherent shortcomings of the Echelle spectrograph and the transmission fiber used in the experiment on the background noise and the absolute intensity of the spectral line were analyzed. Then, the spectral background noise was deducted by the peak clipping algorithms, and the absolute intensity of the spectral line was corrected by using the standard spectral data of the radiometric calibration sources. The spectral line intensity and plasma temperature were compared. It has been shown that the intensity correction has a great influence on the spectral signal with the wavelength less than 380nm forthe alloy steel sample. After the background subtraction and intensity correction, the plasma temperature was reduced from 13 401.75 to 8 980.72 K, and the fitting coefficient of Boltzmann plot for the plasma temperature was increased from 0.60 to 0.91. Therefore, it is necessary to take the spectral pretreatment before spectral data processing. It provides the basis to obtain the reliable spectral data for the qualitative or quantitative analysis of the material composition..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 276 (2018)
The Preparation and Blue Light Emission Characteristic of Ce-Doped Si Nanowires
FAN Zhi-dong, LIU Chuo, LI Xu, MA Lei, and PENG Ying-cai
Si nanowires were prepared from the Si (100) single with polishing and “pyramid” texture surface. The process conditionswere as follows: the growth temperature was 1 100 ℃, N2 gas flow rate 1 500 sccm, growth time 15~60 min, and Au and Au-Al were used metal catalyst, respectively. The diameters of the formed Si nanowirSi nanowires were prepared from the Si (100) single with polishing and “pyramid” texture surface. The process conditionswere as follows: the growth temperature was 1 100 ℃, N2 gas flow rate 1 500 sccm, growth time 15~60 min, and Au and Au-Al were used metal catalyst, respectively. The diameters of the formed Si nanowires are 50~200 nm and the length were from several micrometers to sereral tens of micrometers. Then, Ce-doped Si nanowires were prepared under the temperature of 1 100~1 200 ℃, 1 000 sccm of N2 flow rate, 30~60 min of doping time and CeO2 powder as doping agent. The influences of the different length, density and distribution of Si nanowires on the luminescence of Ce3+ were experimentally investigated. The photoluminescence properties and fluorescence quantum efficiency were test ed and analyzed by the Hitachi F-4600 fluorescence spectrophotometer and the FLS-920 full functional fluorescence spectrometer under room temperature. The results showed that the Ce-doped Si nanowires had a stronly blue luminescencent with an emission peak position at 405 nm(5d→2F5/2) and the full width at half maximum was 36.7 nm when the grow time of Si nanowires was 30min, the surface was “pyramid” texturewith lower density and the optimized excitation wavelength was 328 nm.Compared with the silicon substrate,the Ce-doped Si nanowires appeared strong blue light emission. The fluorescence quantum efficiency reached 65.57%. The color coordinates of Ce-doped Si nanowires was (0.16, 0.16) based on the distribution of emission spectral and CIE-1931 standard formula. Ce-doped Si nanowires have potential applications in the areas of lighting and display because of its strong luminous intensity and relatively high fluorescence quantum efficiency. At the same time this paper has a certain referential value in the field of research and application of Si nanowires..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 281 (2018)
Threshold of Brillouin Scattering in a Few-Mode Fiber
ZHANG Yan-jun, GAO Hao-lei, FU Xing-hu, TIAN Yong-sheng, WANG Hui-min, and ZHANG Yi-nan
Stimulated Brillouin scattering can affect the signal-to-noise ratio, transmission distance and transmission capacity in few-mode fiber transmission system. Stimulated Brillouin scattering is an important factor limiting the input power scaling of the fiber transmission system. In this paper, the threshold of stimulateStimulated Brillouin scattering can affect the signal-to-noise ratio, transmission distance and transmission capacity in few-mode fiber transmission system. Stimulated Brillouin scattering is an important factor limiting the input power scaling of the fiber transmission system. In this paper, the threshold of stimulated brillouin scattering in few-mode fiber was studied. Based on the mathematical model of Brillouin scattering spectrum and intermodal spectrum, the scattering characteristics of the few-mode fiber were analyzed. The Brillouin scattering gain spectrum and the threshold gain coefficients of few-mode fiber were analyzed respectively, as well as the influence of optical fiber parameters on the stimulated brillouin scattering spectrum threshold of few-mode fiber is numerically studied. The results showed that SI-10 step few-mode fiber can transmit five models, and each mode had its own transmission constant and effective refractive index. And each mode interaction leaded to the mode broadening and the gain reduction. At the same time, the Brillouin scattering spectrum gain of the few-mode fiber was 3.9×10-11 m·W-1. The threshold gain coefficient was affected by the distance of the optical fiber sensor, and the threshold gain coefficient was about 18.1 when the fiber was long enough to 22 km. The threshold value of Few-mode Fiber decreased with the increase of the length of the fiber, and the decreasing trend gradually slowed down to a constant about 20.5 dBm. The threshold for each mode of few-mode fiber also decreased with the increase of the length of the fiber, eventually tending to be constant. Moreover, the threshold of different modes increased with the increase of the mode order. The threshold value of few-mode fiber increased with the increase of the fiber attenuation coefficient and the core radius. With the increasing of fiber attenuation coefficient and core radius, the increasing trend of threshold increased slowly. The threshold value of the fiber with different attenuation coefficient tended to be constant at different length. The stimulated Brillouin scattering threshold value of fiber was larger and likely to be a constant with the increase of the attenuation coefficient of fiber..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 285 (2018)
The Research on Reconstruction of Spectral Reflectance in LCTF Imaging System Based on Comparative Measurement
WANG Xia, LIAO Ning-fang, LI Ya-sheng, CHENG Hao-bo, CAO Bin, YANG Wen-ming, and LIN Kai
The spectral camera based on the liquid crystal tunable filter (LCTF) can be used to different platforms due to its advantage of small volume, low power consumption and convenient integration. In addition, LCTF spectral camera identifies the color of the target in the scene according to the spectral reflectance charactThe spectral camera based on the liquid crystal tunable filter (LCTF) can be used to different platforms due to its advantage of small volume, low power consumption and convenient integration. In addition, LCTF spectral camera identifies the color of the target in the scene according to the spectral reflectance characteristic of the target, which can address the problem of metamerism very well. Thus, LCTF spectral camera is also applicable to areas of camouflage recognition and estimation of production of fine agricultural products. The comparative measurement method, which can effectively discount effects of illuminant and background in the scene, has been widely used to reconstruct the spectral reflectance of the target. The comparative measurement method mainly adopts a standard white surface as a reference. However, in some scenes, because of the limitation of the space, it is very difficult to put in a standard white surface. In order to address this question, in this paper, a comparative measurement by referring to the bright targets in the scene obtained by LCTF spectral camera was proposed. In the experiment, five different surfaces in the Gretg Macbeth Color Checker (MCC) were respectively used as references to construct the spectral reflectance of red, green and blue surfaces in MCC. The reconstructed spectral reflectance of red, green and blue surfaces was compared with that measured by a spectrophotometer (X-Rite Color Eye 7000A). Results showed that reflectance curves reconstructed were basically similar with those measured by the spectrophotometer in the shape; root mean square errors for red, green and blue surfaces were all less than 0.05. For blue surface, the reconstructed reflectance was the most accurate by referring to blue-green surface whose reflectance was close to that of blue surface; for red and green surfaces, the reconstructed reflectance was the most accurate by referring to yellow surface which has the second-largest luminance after the white surface; the above reconstructed reflectance was more accurate than that by referring to the standard white surface. Results indicated that the proposed method by referring to the bright surfaces can be used to construct the spectral reflectance of the target very well in LCTF spectral camera. The proposed method is useful in the expansion of application fields of LCTF spectral camera..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 290 (2018)
On-Orbit Spectral Calibration Method of Grating Dispersive Imaging Spectrometer
WANG Hong-bo, HUANG Xiao-xian, FANG Chen-yan, ZHANG Teng-fei, and WEI Jun
Precise spectral calibration is the premise and base for quantitative radiance inversion of Earth scenes. The grating dispersive visible near-infrared imaging spectrometer (VNS) is used for ocean color remote sensing and coastal zones monitoring. A push-broom method is applied by this instrument. It is operated in the Precise spectral calibration is the premise and base for quantitative radiance inversion of Earth scenes. The grating dispersive visible near-infrared imaging spectrometer (VNS) is used for ocean color remote sensing and coastal zones monitoring. A push-broom method is applied by this instrument. It is operated in the solar-reflected spectrum with wavelength range from 400 to 1 040 nm. 256 spectral channels with a nominal 2.5 nm interval and 1024 cross-track pixels, corresponding to spectral and spatial dimensions, are arranged on the focal plane. Spectral parameters including the center wavelength and bandwidth of the hyperspectral instrument may vary after launching, due to external environmental changes or self-performance degenerations. For the sake of coefficients update, an on-orbit spectral calibration method is presented in this contribution. The algorithm is based on a spectrum-matching technique using atmospheric absorption features, solar Fraunhofer lines and Pr-Nd characteristic spectra of the on-board calibrator. Last squares and correlation coefficients are applied to process the data collected in the on-orbit spectral calibration simulation experiments. The procedure is introduced by taking an example of the oxygen absorption 763 nm band. Fraunhofer lines 517 nm, Pr-Nd glass characteristic spectra 685 nm and oxygen absorption 763 nm are selected as three typical bands, corresponding to three channels of the visible near-infrared imaging spectrometer (VNS). Their spectral recalibration results are reported as follows. Cross-track smile effect amplitudes are similar, about 0.6 nm while different center wavelength shifts, 0.707, -0.369 and 0.293 nm respectively. The standard deviation of the channel of 763 nm is smaller than the other two, deriving from second order polynomial fits to measurements across-track, and spectral position precisions of the three channels are better than 0.176 nm. A practical on-orbit spectral calibration algorithm is proposed for the imaging spectrometer..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 296 (2018)
Energy Transfer Mechanism and Up-Conversion Emission Properties in Tm3+/Ho3+ Doped Tellurite Glasses
CHEN Gan-xin, CHENG Yun, and QIAN Qi
The Tm3+ single-doped and Tm3+/Ho3+ co-doped tellurite glasses are prepared by traditional melt quenching technique. The synthesized glasses were characterized with infrared and up-conversion fluorescence spectra has been investigated in terms of the excitation of 808 nm laser, and the up-conversion fluorescence composThe Tm3+ single-doped and Tm3+/Ho3+ co-doped tellurite glasses are prepared by traditional melt quenching technique. The synthesized glasses were characterized with infrared and up-conversion fluorescence spectra has been investigated in terms of the excitation of 808 nm laser, and the up-conversion fluorescence composed of four emission bands centering around 695, 544, 474 and 740 nm wavelengths, respectively. The 740 nm emission band seldom reported is possibly assigned to the Tm3+: 1D2→3F2, 3 transition by analyzing the spectra properties of the glass samples and relevant energy transfer mechanism. The intensities of 740, 695 and 474 nm emission in the tellurite glass at the concentration of 0.5 mol% of Tm2O3 and 0.3 mol% of Ho2O3 are almost 3, 2.5 and 14 times larger than those in the tellurite glass at the concentration of 0.5 mol% of Tm2O3, respectively. These obviously indicate that there is backward energy transfer from Ho3+ to Tm3+. The population for the energy level 1D2 (emitting 740 nm red) of Tm3+ in Tm3+ single-doped tellurite glass is significantly originated from cooperative up-conversion (CU). However, the population for the energy level 3F2, 3 (emitting 695 nm red) of Tm3+ is not only resulted from the process of CU, but also from the 1D2→3F2, 3 transition and the relaxation of the level 1G4 of Tm3+. Hence, the intensity of 695 nm emission is evidently higher than that of 740 nm emission in the samples. Because of the cross relaxation CR2 and CR3, as well as backward resonant energy transfer RET2, there is a net increase of population for the level 1G4 (emitting 474 nm blue) of Tm3+ in the Tm3+/Ho3+ co-doped tellurite glass compared to the Tm3+ single-doped tellurite glass while the two glasses are conformed with the concentration of Tm3+. The net increase of population for the level 1G4 of Tm3+ is possible to reinforce the multi-phonon relaxation process of this level, emission of 740 nm red light, as well as CU process, and further enhance the population for the level 3F2, 3 of Tm3+. Therefore, the intensities of red and blue fluorescence in the Tm3+/Ho3+ co-doped tellurite glass are clearly greater than those in the Tm3+ single-doped tellurite glass. The effects of cross relaxation and energy transfer between Tm3+ and Ho3+ are studied, while the energy transfer mechanism between Tm3+ and Ho3+ is also further discussed in the work..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 302 (2018)
Fast and High-Accuracy Measuring Technique for Transmittance Spectrum in VIS-NIR
WANG Sheng-hao, LIU Shi-jie, WANG Wei-wei, and ZHANG Zhi-gang
In this paper, based on the framework of traditional spectrophotometry, we put forward a novel fast and high-accuracy technique for measuring transmittance spectrum in VIS-NIR wave range, in which its key feature was that during the measurement procedure, the output wavelength of the grating monochromator was kept incrIn this paper, based on the framework of traditional spectrophotometry, we put forward a novel fast and high-accuracy technique for measuring transmittance spectrum in VIS-NIR wave range, in which its key feature was that during the measurement procedure, the output wavelength of the grating monochromator was kept increasing continuously and at the same time, the photoelectric detectors execute d a concurrently continuous data acquisition routine. Initial experiment result showed that the newly proposed technique could shorten the time consumed for measuring the transmittance spectrum down to 50% that of the conventional spectrophotometric method, and a relative error of 0.070% and a repeatability error of 0.042% were generated. Compared with the current mostly used techniques (spectrophotometry, methods based on multi-channel spectrometer and strategy using Fourier transform spectrometer) for obtaining transmittance spectrum in VIS-NIR, the new strategy has at all once the following advantages. Firstly the measuring speed could be greatly quicken, and fast measurement of transmittance spectrum in VIS-NIR is therefore promising, which would find wide application in dynamic environment. Secondly high measuring accuracy (0.1%~0.3%) is available, and finally the measuring system has high mechanical stability because the motor of the grating monochromator is rotating continuously during the measurement..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 308 (2018)
Single- and Dual-Pulse Laser Induced Breakdown Spectroscopy for Aluminum in Liquid Jets
WANG Li, XU Li, XU Wei-qing, YAO Guan-xin, ZHENG Xian-feng, and CUI Zhi-feng
A homemade experimental setup of laser-induced breakdown spectroscopy (LIBS) with aqueous jets was used to compare the detection results of dual-pulse (DP-LIBS) and single-pulse laser-induced breakdown spectroscopy (SP-LIBS) for heavy metal elements in liquids. Two Q-switched Nd∶YAG lasers that operated at 532 nm were A homemade experimental setup of laser-induced breakdown spectroscopy (LIBS) with aqueous jets was used to compare the detection results of dual-pulse (DP-LIBS) and single-pulse laser-induced breakdown spectroscopy (SP-LIBS) for heavy metal elements in liquids. Two Q-switched Nd∶YAG lasers that operated at 532 nm were utilized to generate plasma on the AlCl3 aqueous jets. The plasma emission signal was detected by spectrometer with an intensified charge-coupled device (ICCD). The effects of laser-pulse energy, ICCD gate width, and ICCD gate delay on the intensity of the Al spectral line at 396.15 nm were presented for SP-LIBS. Experimental results showed the optimum parameters for laser energy, ICCD gate width, and gate delay were 50 mJ, 150 ns, 1 200 ns, respectively. The influence of experimental parameters, including interpulse delay, total pulse energy, and ICCD gate delay on the signal enhancement of the Al 396.15 nm spectral line intensity was investigated and optimized. Results showed that the optimal parameters for interpulse delay, total pulse energy, and ICCD gate delay were 1 000 ns, 50 mJ, 1 100 ns respectively. The detection limits of Al were 26.79 and 10.80 ppm by SP-LIBS and DP-LIBS, respectively. The results indicated that DP-LIBS can improve the detection sensitivity which offers a feasible basis for the detection of metallic elements in liquid..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 314 (2018)
Theoretical Study on 13C Nuclear Magnetic Resonance Spectra of Several Coumarin Derivatives
JIA Fei-yun, SU Feng-fa, RAN Ming, and ZHANG Bo
The structure of the six kinds of coumarin derivatives has been optimized at the level of B3LYP/6-311G (d, p), under which the stability has been verified by means of Vibration analysis. Moreover, NMR Spectra of the coumarin derivatives compounds have been studied at the level of B3LYP/6-311G (d, p) by GIAO method. TheThe structure of the six kinds of coumarin derivatives has been optimized at the level of B3LYP/6-311G (d, p), under which the stability has been verified by means of Vibration analysis. Moreover, NMR Spectra of the coumarin derivatives compounds have been studied at the level of B3LYP/6-311G (d, p) by GIAO method. The results showed that the structure of the six compounds, a larger conjugated system, had good planarity. Different Substituents and different positions of substituents all have different influences on NMR of the several coumarin derivatives. In general, after the hydrogen atom on the benzene ring is substituted by other groups, the δ value of the α-C atom next to the substituent changes obviously, the δ value of the Ortho carbon atoms have great change too, but the δ value of the meta carbon atom have almost no change. The effect of electronegativity of substituents on α-C atoms presents obvious regularity, while the influence of conjugate effect on carbon atoms of benzene ring is more complex. Finally, in order to show the correlation between theoretical calculation and experimental values, we showed the correlation diagram of the chemical shift values of the six kinds of derivatives, and carried on the linear regression. Results showed that the correlation between the chemical shift theory and the experimental value of the six kinds of the Coumarin derivatives was very good..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 320 (2018)
The Diagnostic Methods for Resurgences of Smoldering Fire in the Forests by Infrared Thermal Imaging
HE Cheng, LIU Ke-zhen, SHU Li-fu, HONG Xia-fang, and ZHANG Si-yu
The embers in the forests are hard to be extinguished because of their smoldering combustion, such as concealing, long burning, invisible inspection and easy resurgence. To find the smoldering combustions timely and efficiently and to explore the characteristics and rules for the resurgences, a series of experiments haThe embers in the forests are hard to be extinguished because of their smoldering combustion, such as concealing, long burning, invisible inspection and easy resurgence. To find the smoldering combustions timely and efficiently and to explore the characteristics and rules for the resurgences, a series of experiments have been presented in this study. With the help of a drone equipped with thermal infrared imaging system and meteorological data collection system, some experiments were conducted in the poplars in Nanjing Forest Police College, where ignitions were set, lighted, put out and resurged by human intervention. The embers were observed by the Infrared Radiometer on the drone in the daytime and at night. The results showed that the dispersion was bigger when the temperature of smoldering combustion was between 500～600 ℃, and the easier resurgence in the daytime than at night suggested that the higher external temperature the ember was, the easier resurgent it was. It was pointed that the temperature in forests was relatively stable in different plots and in different time, with a standard deviation of 1 and 9. The standard deviation of temperature data on the infrared images of embers varied from 30 to 85 and it revealed that the values between 80 and 85 would be suspected. In this method, the surroundings and parameter threshold of temperature in the smoldering combustions could be quantified to determine their eigen values of embers in the forests. It is reasonable for the researchers at this point to promote the development of the technology in the forest-fire prevention and the decision-makers to ask which results could provide some important methods and data for safe fire-fighting..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 1, 326 (2018)
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