Journals >Spectroscopy and Spectral Analysis
Contents
2015
Volume: 35 Issue 3
56 Article(s)
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Research Article
Laser Tuning Performance Testing and Optimization in TDLAS Oxygen Measuring Systems
HE Jun-feng, HU Jun, KAN Rui-feng, XU Zhen-yu, and WANG Tao
TDLAS (tunable diode laser absorption spectroscopy) technology, with its unmatched advantages such as high selectivity molecular spectra, fast response, high sensitivity, non-contact measuring, become the preferred scheme for combustion process diagnosis, and can be effectively used for oxygen measuring. DFB (distributTDLAS (tunable diode laser absorption spectroscopy) technology, with its unmatched advantages such as high selectivity molecular spectra, fast response, high sensitivity, non-contact measuring, become the preferred scheme for combustion process diagnosis, and can be effectively used for oxygen measuring. DFB (distributed feedback) laser diode with its small size, low power consumption, long service life, narrow linewidth, tunable wavelength has become the main choice of the TDLAS system. Performance of laser tuning characteristics is a key factor restricting TDLAS’s measuring performance. According to TDLAS oxygen measuring system’s working requirements, a simple experimental method was used to test and analyze tuning characteristics such as wavelength current, power current and wavelength temperature of a 764 nm DFB laser diode in the system. Nonlinear distortion of tuning curves was obvious, which affects oxygen measuring accuracy. The laser spectra’s characteristics such as narrow linewidth, high side mode suppression ratio and wide wavelength tuning range are obvious, while its wavelength-current tuning curve with a tuning rate of about 0.023 nm·mA-1 is not strictly linear. The higher the temperature the greater the threshold current, the PI curve is not strictly linear either. Temperature tuning curve is of good linearity, temperature-wavelength tuning rate keeps constant of about 0.056 nm/DEG C. Temperature tuning nonlinearity can be improved by high temperature control accuracy, and current power nonlinearity can be improved by setting the reference light path. In order to solve the wavelength current tuning nonlinear problems, the method of DA controlling injection current was considered to compensate for non-linear wavelength current tuning according to DFB laser diode tuning mechanism and polynomial fitting of test results. In view of different type of lasers, this method needs only one polynomial fitting process before the system’s initial work. The compensation scheme is reasonable and the realization is simple, what’s more, it does not affect the measuring process. The experiments prove that λI curve’s linear fit residuals are less than 1 pm after compensation, far less than those of before compensation 22 pm, the compensation effect is obvious, which provided a basis for various oxygen parameters’ TDLAS measuring and inversion..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 577 (2015)
Study on the Low Temperature Photoluminescence Spectra of Ⅱ-Ⅵ Group Telluride Bulk Crystals
XU Ya-dong, LIU Hang, HE Yi-hui, ZHOU Yan, and JIE Wan-qi
The dominant point defects in Ⅱ-Ⅵ group telluride bulk crystals grown from melt usually varied due to different growth conditions and cooling history, in turn affect the electrical and optical behaviors of corresponding single crystals and devices. Low temperature photoluminescence (PL) spectra acts as a contact-less aThe dominant point defects in Ⅱ-Ⅵ group telluride bulk crystals grown from melt usually varied due to different growth conditions and cooling history, in turn affect the electrical and optical behaviors of corresponding single crystals and devices. Low temperature photoluminescence (PL) spectra acts as a contact-less and non-destructive technique, can be used to evaluate the behaviors of point defects and impurities in the as-grown telluride bulk crystals. With the purpose of comparing the defect structures in un-doped ZnTe and CdTe crystals grown under Te-rich condition, 8.6 K PL spectra were obtained. The conductivity type and resistivity were investigated by Hall-effect measurements at room temperature (RT). For p-type low resistivity ZnTe crystal, the intensity of free electron to neutral acceptor (e, A0) transition is higher than the donor-acceptor pair (DAP) transition, which predominates in the PL spectra. However, in the contrary, DAP peak dominates the PL emissions for n-type high resistivity CdTe. This difference is mainly attributed to the distinct properties of the grown-in point defects due to different growth velocities and cooling processes. In terms of the un-doped CdZnTe crystal grown under stoichiometry, neutral donor bound exciton (D0, X) emission is predominated in the 9.2 K PL spectra, with the intensity of (e, A0) peak is higher than DAP peak, which then overlaps to each other when the temperature higher then 15 K. In the case of In-doped CdZnTe crystal grown by Te-rich situation, A-center emission is clearly observed, which introduces an energy level approximately of 0.15 eV, with the intensity proportional to the concentration of indium dopant. This defect is seemingly related to the complex of［In+CdV2-Cd］- formed by a shallow donor InCd and Cd vacancy..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 582 (2015)
A Algorithm of the Singular Value Decomposition for Three-Way Array
ZHU Er-yi, WANG Xiao-hua, and HANG Wei
A algorithm of the singular value decomposition for three-way array is proposed in this paper. The algorithm is suitable to deal with the actual problems of pattern recognition and classification model with three-way array data. Similar to the algorithm of the singular value decomposition for matrix, the algorithm is oA algorithm of the singular value decomposition for three-way array is proposed in this paper. The algorithm is suitable to deal with the actual problems of pattern recognition and classification model with three-way array data. Similar to the algorithm of the singular value decomposition for matrix, the algorithm is obtained by saving the problem of extremum subject to constraint conditions. Comparing with the existent algorithms of trilinear decomposition the algorithm is simple and fast in calculation, suitable to deal with the actual bigger data problems. The algorithm is easy to expand into the situation for multi-way array spectral data..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 587 (2015)
Influence of Argon Content on Plasma Temperature of Single Filament in Dielectric Barrier Discharge
FU Hong-yan, DONG Li-fang, and ZHAO Yang
The single filament (also referred to as monofilament) which composed of two parts including the center spot and the outer halo is observed and researched for the first time in dielectric barrier discharge, which filled with gas-mixture of argon and air. The pictures taken from the experiment show that the diameter of The single filament (also referred to as monofilament) which composed of two parts including the center spot and the outer halo is observed and researched for the first time in dielectric barrier discharge, which filled with gas-mixture of argon and air. The pictures taken from the experiment show that the diameter of the monofilament decreases with the increasing of the content of the argon in the argon-air mixture, and at the same time there is an obvious difference on brightness between the center spot and the outer halo. All of these phenomenons suggest that the center spot and the outer halo are probably in different plasma state. The micro character of the center spot and the outer halo is researched seriously in the experiment by the time-resolved measurement with optical method. Three plasma temperatures of the center spot and the outer halo in single filament in different argon content are studied in details by using optical emission spectra. The emission spectra of the N2 second positive band(C3Πu→B3Πg) are measured, from which the molecule vibrational temperature of the center spot and the outer halo are calculated. Based on the relative intensity of the N+2 line at 391.4 nm and the N2 line at 394.1 nm, the changing relationship of the average electron energy of the center spot and the outer halo with argon content is investigated. The spectral lines of Ar I 763.2 nm (2P6→1S5) and 772.077 nm (2P2→1S3) are chosen to estimate electron excitation temperature of the center spot and the outer halo by the relative intensity ratio method. The results show that the optical signal corresponding to the first lasge pulse is the center spot, whose signal intensity is a litter weaker; and the optical signal containing the whole pulse is the outer halo, whose signal intensity is stronger. The three plasma temperatures including the molecule vibrational temperature, average electron energy and electron excitation temperature of the outer halo are higher than those of the spot at the same argon content without exception. In addition, the molecule vibrational temperature of the center spot and the outer halo decrease with the argon content increases from 30% to 50%, while on the other hand, electron excitation temperature and average electron energy are decrease gradually..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 591 (2015)
Research on L-Ascorbic Acid and Thiamine Based on Wide-Band Terahertz Spectroscopy Technique
LI Chun, LI Miao, and JIANG Ling
We employed terahertz time-domain spectra (THz-TDS) and Fourier transform infrared spectra (FTIR) to measure the terahertz spectroscopy of L-ascorbic acid and thiamine in the frequency region ranging from 0.10 to 3.50 THz. Molecular models of two vitamins have been shown, and based on above two spectroscopies, we compaWe employed terahertz time-domain spectra (THz-TDS) and Fourier transform infrared spectra (FTIR) to measure the terahertz spectroscopy of L-ascorbic acid and thiamine in the frequency region ranging from 0.10 to 3.50 THz. Molecular models of two vitamins have been shown, and based on above two spectroscopies, we compared the differences about the absorption spectra between the L-ascorbic acid and the thiamine. The measured results show that the absorption spectra obtained based on THz-TDS and FTIR are completely consistent in the frequency range of 0.70 to 3.00 THz. New fingerprint peaks obtained by the FTIR in the low frequency region from 0.30 to 0.50 THz in terms of high sensitive silicon bolometer detector, which are not found by the THz-TDS. Furthermore, several bands at 8.75, 8.85, 9.00, 9.30 and 10.30 THz, fingerprint peaks have been found in the frequency region from 8.00 to 12.00 THz for the thiamine sample obtained by the FTIR. Measurement results indicate the absorption spectra depend on the ratio of polyethylene powder mixed with the L-ascorbic acid. L-ascorbic acid has a lower absorption ability at THz band, so pure samples should be used for testing experiment. In addition, we calculated the refractive index for the two samples. This study has important implications for the discriminatory analysis of vitamins and the establishment of vitamin spectroscopy standard database..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 595 (2015)
Research on Application of Fourier Transform Infrared Spectrometry in the Diagnosis of Lymph Node Metastasis in Gastric Cancer
BAI Yue-kui, YU Li-wei, ZHANG Le, FU Jing, LENG Hui, YANG Xiao-jun, MA Jun-qiang, LI Xiao-juan, LI Xiu-juan, ZHU Qing, ZHANG Yuan-fu, LING Xiao-feng, and CAO Wen-lan
To explore the feasibility of quick intraoperative in situ and noninvasive diagnosis of lymph node metastasis in gastric cancer by Fourier transform infrared (FTIR) spectrometry. FTIR spectra of surgically removed fresh lymph nodes were measured by FTIR via probe of attenuated total reflection (ATR). For each spectrum,To explore the feasibility of quick intraoperative in situ and noninvasive diagnosis of lymph node metastasis in gastric cancer by Fourier transform infrared (FTIR) spectrometry. FTIR spectra of surgically removed fresh lymph nodes were measured by FTIR via probe of attenuated total reflection (ATR). For each spectrum, 13 bands were indentified and assigned between 3 000 and 1 000 cm-1. Peaks in the spectra were measured and relative intensity ratios were calculated and compared between the spectra of Metastatic lymph nodes (MLN) and Non-metastatic lymph nodes(NMLN). Standard statistic analysis was performed. 720 lymph nodes were measured in 38 gastric cancer patients. Results show that there were significant differences between the FTIR of 540 MLN and 180 NMLN. (1) For the band related to nucleic acid: The ratios of I1 240/I1 460(p=0.015) and I1 080/I1 460(p=0.034)increased in MLN, which shows that the relative quantity of nucleic acid was more in MLN than that in NMLN. (2) For the bands related to protein: The ratios of I1 640/I1 460(p=0.001) and I1 546/I1 460(p=0.027) increased in MLN, which shows that the relative quantity of protein was more in MLN. (3) For the bands related to lipid: The ratio of I2 855/I1 460 and I1 740/I1 460 decreased in MLN FTIR spectrum, indicating the lower relative quantity of lipid in MLN. (4) For the bands related to carbohydrate: The ratio of I1 160/I1 460(p=0.023) decreased in MLN FTIR spectrum, indicating the lower relative quantity of carbohydrate in MLN. The results demonstrate that the FTIR spectroscopy technique maybe develop into a promising method for in situ and quick intraoperative differential diagnosis of lymph node metastasis in gastric cancer..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 599 (2015)
Infrared Spectrum Studies of Hydrocarbon Generation and Structure Evolution of Peat Samples During Pyrolysis and Microbial Degradation
BAO Yuan, JU Yi-wen, WEI Chong-tao, WANG Chao-yong, and LI Xiao-shi
Hydrocarbon generation and structural evolution would be occurred in the process of from coal-forming material (i.e. peat sample) transforming to the coal. While Fourier Transform Infrared Spectroscopy (FTIR) have a special advantages in analyzing molecular structure of samples. For understanding the characteristics ofHydrocarbon generation and structural evolution would be occurred in the process of from coal-forming material (i.e. peat sample) transforming to the coal. While Fourier Transform Infrared Spectroscopy (FTIR) have a special advantages in analyzing molecular structure of samples. For understanding the characteristics of hydrocarbon generation and structural evolution of coal-forming material during the process of pyrolysis and microbial degradation, based on the physical simulation experiments of closed pyrolysis and anaerobic microbial degradation, the generation potential of thermogenic gas and biogenic gas were studied in this paper, and characteristics of molecular structure evolution and its mechanism was analyzed by FTIR technology. Results show that cumulative gas yields of hydrocarbon gases (mainly for methane) increased with experiment temperature. The gas yield of non-hydrocarbon gas (mainly for CO2) exhibited two peaks at 250 and 375 ℃. The degradation ability of anaerobe on coal samples weakened with the maturity increasing and there was no gas generation on the pyrolysis samples with maturity from 1.6% to 1.8%. After pyrolysis, the content of hydroxyl in peat sample decreased first and then increased with the pyrolysis temperature increasing. The content of aldehyde carbonyl, methylene and phosphate reduced. The content of aromatic esters decreased with nonlinear. The bone of S-O in stretching vibration appeared after 350 oC and its content increased with temperature. This shows that the sulfocompound restrains the activity of methanogenic bacteria. After degradation by anaerobe, the relative content of hydroxyl, aldehyde carbonyl, aromatic esters, methylene and phosphate in peat sample dropped significantly. It is shown that the intermolecular force between these groups weakened..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 603 (2015)
Establishment and Application of Model for Determining Oil Content of Cottonseed Using Near Infrared Spectroscopy
SHANG Lian-guang, LI Jun-hui, WANG Yu-mei, LI Yu-hua, WANG Dan, XIONG Min, and HUA Jin-ping
Cotton is one of the important oil crops, and it is great significance for screening and identification of breeding materials to establish a method of the rapid, nondestructive testing of cotton seed oil content. In this study, near-infrared diffuse reflection spectroscopy of 118 high and low oil materials were adoptedCotton is one of the important oil crops, and it is great significance for screening and identification of breeding materials to establish a method of the rapid, nondestructive testing of cotton seed oil content. In this study, near-infrared diffuse reflection spectroscopy of 118 high and low oil materials were adopted to establish models for fast nondestructive determining oil content of cottonseed using near infrared spectroscopy (NIR). One hundred and six cottonseed samples as calibration set that covered the range of seed oil content for upland cotton were used in this experiment. The spectral data of cottonseed were processed using the first derivative and multiplicative scatter correction (MSC). The correction NIR model of oil content was built based on partial least squares (PLS) method with the spectral regions 5 446～8 848 cm-1 and main components (5). The determination coefficient (R2) of calibration model was 0.975, standard error of calibration (SEC) was 0.67. The authors test the model’s actual ability to predict using external validation set. The correlation coefficient (r) of predicted values and the chemistry value was 0.978, the range of prediction error was 0.1%～1.7%. The model established has good predictability. The oil content of 784 breeding stocks were predicted by NIR model, statistical analysis of predictable results elucidated that the NIR model of oil content developed can be well applied to selective breeding and oil related study in cotton..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 609 (2015)
Study on Archaeological Lime Powders from Taosi and Yinxu Sites by FTIR
WEI Guo-feng, ZHANG Chen, CHEN Guo-liang, HE Yu-ling, GAO Jiang-tao, and ZHANG Bing-jian
Archaeological lime powders samples from Taosi and Yinxu sites, natural limestone and experimentally prepared lime mortar were investigated by means of Fourier transform infrared spectrometry (FTIR) to identify the raw material of lime powders from Taosi and Yinxu sites. Results show that ν2/ν4 ratio of calcite resulteArchaeological lime powders samples from Taosi and Yinxu sites, natural limestone and experimentally prepared lime mortar were investigated by means of Fourier transform infrared spectrometry (FTIR) to identify the raw material of lime powders from Taosi and Yinxu sites. Results show that ν2/ν4 ratio of calcite resulted from carbonation reaction of man-made lime is around 6.31, which is higher than that of calcite in natural limestone and reflects the difference in the disorder of calcite crystal structure among the natural limestone and prepared lime mortar. With additional grinding, the values of ν2 and ν4 in natural limestone and prepared lime mortar decrease. Meanwhile, the trend lines of ν2 versus ν4 for calcite in experimentally prepared lime mortar have a steeper slope when compared to calcite in natural limestone. These imply that ν2/ν4 ratio and the slope of the trend lines of ν2 versus ν4 can be used to determine the archaeological man-made lime. Based on the experiment results, it is possible that the archaeological lime powder from Taosi and Yinxu sites was prepared using man-made lime and the ancient Chinese have mastered the calcining technology of man-made lime in the late Neolithic period about 4 300 years ago..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 613 (2015)
The Interaction of Oil Microcapsule Wall Materials between Whey Protein and Acacia
SHI Yan, LI Ru-yi, WANG Hui, LI Qian, LI De-jun, and TU Zong-cai
The interaction between whey protein and acacia which were used as wall material was studied on the formation of the oils microcapsules by the FTIR Spectroscopy and Computer Aided Analysis. The results indicated that whey protein changed obviously in amide A and amideⅠ by high pressured homogenization and spray-drying.The interaction between whey protein and acacia which were used as wall material was studied on the formation of the oils microcapsules by the FTIR Spectroscopy and Computer Aided Analysis. The results indicated that whey protein changed obviously in amide A and amideⅠ by high pressured homogenization and spray-drying. The amide A moved from 3 406.5 cm-1 to 3 425.4 cm-1 which was possibly due to covalent cross-linking between whey protein and acacia. Furthermore the amide Ⅰ moved from 1 648.6 cm-1 to 1 654.7cm-1 for intramolecular hydrogen bonding of protein had been weaken. After Gaussian fitting on amide Ⅰ, it was found that the content of secondary structure of α-helix content andβ-fol.ding in whey protein reduced from 19.55% to 17.50% and from 30.59% to 25.63%, respectively. This suggests that protein intramolecular hydrogen bonding force was abated, resulting in abating the rigid structure of the protein molecules and enhancing of the toughness structure. The protein molecules showed some flexibility. The result of SDS-PAGE electrophoresis showed that whey protein - gum Arabic complexes produced covalent products in larger molecular weight. During the spray-drying process, covalent cross-linking produced between whey protein and gum Arabic which improved emulsifying activity of the complex whey protein and gum Arabic produced covalent cross-linking and improved the complex emulsifying activity. Observing the surface structure of the fish oil microcapsule by SEM, the compound of whey protein and acacia as wall material was proved better toughness, less micropore, and more compact structure..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 617 (2015)
Quality Analysis of Peanut Seed by Visible/Near-Infrared Spectra
ZHENG Tian-tian, SUN Teng-fei, CAO Zeng-hui, and ZHANG Jun
In this paper, three representative varieties of peanut seeds were selected for the experiment based on visible/near-infrared reflectance spectroscopy living in the wavelength rang from 600 to 1 100 nm.Firstly, spectral datas ware collected by the near-infrared fiber optic spectrometer, and the spectral features of theIn this paper, three representative varieties of peanut seeds were selected for the experiment based on visible/near-infrared reflectance spectroscopy living in the wavelength rang from 600 to 1 100 nm.Firstly, spectral datas ware collected by the near-infrared fiber optic spectrometer, and the spectral features of the original spectral dates were extracted by the wavelet analysis.Then the principal component analysis (PCA) was used for cluster analysis of spectral features. Finally, the four principal components were applied as the inputs, the varieties category as the output and the Mahalanobis distance as the discriminant function of the recognitionmodel, so a linear discriminant analysis model was established.In the 50 samples of each varieties, 30 samples were randomly selected as the training set, and the remaining 20 samples as the predictor set. The recognitionmodel for three peanut varieties have a recognition rate of 95% on average. As the experimental results show that this method is reliable and effectively, and a new method to distinguish and discriminate the quality of peanut seeds was put forword..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 622 (2015)
Determination of Carbon Dioxide in Refined Titanium Tetrachloride by Infrared Spectroscopy
SONG Guang-lin, LUO Yun-jun, LI Jin-qing, and TAN Hong
Refined TiCl4 is the key procedure in producing titanium sponge. Besides, the content of carbon and oxygen (C and O) impurities in titanium sponge and that of C and O impurities in refined TiCl4 presents the 4-times enrichment relationship. Therefore, the content control of the C and O impurities in refined TiCl4 becomRefined TiCl4 is the key procedure in producing titanium sponge. Besides, the content of carbon and oxygen (C and O) impurities in titanium sponge and that of C and O impurities in refined TiCl4 presents the 4-times enrichment relationship. Therefore, the content control of the C and O impurities in refined TiCl4 becomes the key part for the quality control of titanium material. In order to control the oxygen and carbon, there is the need to analyze the source of C and O impurities so that strict control can be conducted over the impurities of refined TiCl4. Determination of CO2 in refined TiCl4 was significant for analysis of its impurities. CO2 could be determined by infrared spectroscopy due to its infrared characteristic spectrum line. However, normal infrared absorption cell was not fit for the sample analysis, because TiCl4 easily reacted with moisture in the air and immediately was hydrolyzed to form highly corrosive hydrochloric acid smoke. According to Lambert-Beer Law, which means the concentration (cx) and absorbance(A)～length (L) curve’s slope have direct ratio. The infrared absorption cell with the window film of ZnSe ( 10 mm×1 mm, wavenumers: 7 800～440 cm-1) and the glass cell (optical path: 42, 22, 12, 7 and 4 mm) was assembled and utilized in determination of the CO2 in refined TiCl4 by standard addition method. The detection limit of CO2 was 0.92 mg·kg-1, the regression equation was Y=0.031 1X, R=0.997 2; With standard addition method, the regression equation of CO2 was Y=0.131 7X, R=0.998 6, it’s good in linearity relation, the CO2 content in refined TiCl4 is determined to be 1.53 mg·kg-1 and SD up to 0.04 mg·kg-1. RSD of the method precision is between 0.53%～1.27%, while recovery rate is between 89.2%～96.8%. This infrared absorption device was safe, simple and convenient, easily removable and washable, and re-useable. The method could conduct the quantitative analysis over the CO2 content in refined TiCl4 through adding standard sample for one time, it could meet the requirement of determination of CO2 in refined TiCl4..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 626 (2015)
Infrared Spectra Characteristics of the Silicate Nickel Ores: A Comparison Study on Different Ore Samples from Indonesia and China
YANG Meng-li, FU Wei, WANG Bao-hua, ZHANG Ya-qian, HUANG Xiao-rong, and NIU Hu-jie
The silicate nickel ores developed in the lateritic nickel deposit, from Kolonodale, Sulawesi Island, Indonesia, and Yuanjiang, Yunnan province, China, were selected for the present study. The X-ray diffraction and Fourier infrared spectra were used to analyze the mineralogical attribute of laterite nickel ores from twThe silicate nickel ores developed in the lateritic nickel deposit, from Kolonodale, Sulawesi Island, Indonesia, and Yuanjiang, Yunnan province, China, were selected for the present study. The X-ray diffraction and Fourier infrared spectra were used to analyze the mineralogical attribute of laterite nickel ores from two different places. The results show that these two different silicate nickel ores have unique infrared spectra characteristics individually, which contributes to the ore classification. The silicate nickel ores from Kolonodale deposit, Indonesia, can be classified as the serpentine type, the montmorillonite+serpentine type, and the garnierite type. While, the silicate nickel ores from Yuanjiang deposit, China, can be classified as the serpentine type and the talc+serpentine type. Moreover, the mineral crystallinity of Yuanjiang nickel ores is generally better than Kolonodale nickel ores. According to the advantage of infrared absorption spectra in distinguishing mineral polytypes, it can be determined that lizardite is the main mineral type in the silicate nickel ores of the two deposits, and there is no obvious evidence of chrysotile and antigorite’s existence. The characteristic of infrared absorption spectra also shows that frequency change of OH libration indicates Ni (Fe) replacing Mg in the serpentine type nickel-bearing mineral, that is, OH libration of serpentine moves to higher frequency, with the proportion of Ni (Fe) replacing Mg increasing..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 631 (2015)
Effect on Fermi Resonance by Some External Fields: Investigation of Fermi Resonance According to Raman Spectra
JIANG Xiu-lan, SUN Cheng-lin, ZHOU Mi, LI Dong-fei, MEN Zhi-wei, LI Zuo-wei, and GAO Shu-qin
Fermi resonance is a phenomenon of molecular vibrational coupling and energy transfer occurred between different groups of a single molecule or neighboring molecules. Many properties of Fermi resonance under different external fields, the investigation method of Raman spectroscopy as well as the application of Fermi reFermi resonance is a phenomenon of molecular vibrational coupling and energy transfer occurred between different groups of a single molecule or neighboring molecules. Many properties of Fermi resonance under different external fields, the investigation method of Raman spectroscopy as well as the application of Fermi resonance, etc need to be developed and extended further. In this article the research results and development about Fermi resonance obtained by Raman spectral technique were introduced systematically according to our work and the results by other researchers. Especially, the results of the behaviors of intramolecular and intermolecular Fermi resonance of some molecules under some external fields such as molecular field, pressure field and temperature field, etc were investigated and demonstrated in detail according to the Raman spectra obtained by high pressure DAC technique, temperature variation technique as well as the methods we planed originally in our group such as solution concentration variation method and LCOF resonance Raman spectroscopic technique, and some novel properties of Fermi resonance were found firstly. Concretely, (1) Under molecular field. a. The Raman spectra of C5H5N in CH3OH and H2O indicates that solvent effect can influence Fermi resonance distinctly; b. The phenomena of the asymmetric movement of the Fermi resonance doublets as well as the fundamental involved is tuned by the Fermi resonance which had not been found by other methods were found firstly by our variation solution concentration method; c. The Fermi resonance properties can be influenced distinctly by the molecular group reorganization induced by the hydrogen bond and anti-hydrogen bond in solution; d. Fermi resonance can occurred between C7H8 and m-C8H10, and the Fermi resonance properties behave quite differently with the solution concentration; (2) Under pressure field. a. The spectral lines shift towards high wavenumber with increasing pressure, and frequency difference Δ varies with pressure, which induced the change of W; b. The W of ν1+ν4～ν3 of CCl4 in C6H6 decreased more quickly in solution than in pure liquid with increasing pressure and the Fermi resonance disappeared ahead of that in pure liquid, which indicates that the phenomenon of Fermi resonance induced by pressure effect can reveal the mechanism of some solvent effects. (3) Under temperature field. a. The Fermi resonance properties of different molecules behave quite differently with temperature. For an instance, the one of CO2 can be influenced distinctly by temperature, while the one of CS2 behaves no change with temperature. This article offers systematic theoretical and experimental support to the investigation of identification and assignment of molecular spectral line, the confirmation of molecular conformation and conformers, the effect of hydrogen bond on molecular structure and properties, etc..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 635 (2015)
Raman Spectroscopy Measurement System of Dual Wavelength Laser Module
FAN Xian-guang, LI Fan, WANG Xin, XU Ying-jie, ZENG Yong-ming, and CHEN Qi-zhen
Fluorescence interference is one of common interference factors during detection of Raman spectroscopy, while shifted-excitation Raman difference spectroscopy (SERDS) is an effective detection means to reject it. SERDS excites the test substance by two laser with different wavelengths, then difference the obtained RamaFluorescence interference is one of common interference factors during detection of Raman spectroscopy, while shifted-excitation Raman difference spectroscopy (SERDS) is an effective detection means to reject it. SERDS excites the test substance by two laser with different wavelengths, then difference the obtained Raman spectroscopies. SERDS can eliminate the fluorescence interference effectively, because the fluorescence backgrounds of the two spectroscopies are the same while the Raman peaks are translated. The key factor of SERDS is the stability of the two excitation light wavelengths, the instability of wavelength difference would seriously affect the characteristics of the Raman peak reproduction. In this paper, the Raman spectroscopy measurement system is presented, where dual wavelength laser module can stably produce two bunch of excitation light (respectively 784.7 and 785.8 nm), which satisfies the requirements of SERDS detection. The major factors influencing wavelength of the laser are laser power and temperature. The system monitors them in real time to guarantee the stability of exciting light’s wavelength. The hardware framework of this measurement system is mainly composed of ARM, dual wavelength laser module as well as its driving circuit, temperature control circuit, a digital optical switch, a spectrometer; the software of this system can achieve the Raman spectrogram automatically and then carry on the subsequent processing. The stability tests of this system for drive current and laser temperature are done. The experimental results demonstrate that the range of current proves to be less than 0.01 mA, the range of temperature less than 0.004 ℃. The system can guarantee the stability of excitation wavelength effectively. Finally, perform the Raman spectroscopy detection to sesame oil of some brand and get good results..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 640 (2015)
Raman Signal Enhancement for Gas Detection Using a Near Concentric Cavity
YANG De-wang, GUO Jin-jia, DU Zeng-feng, WANG Zhen-nan, and ZHENG Rong-er
The detection of dissolved gases in seawater plays an important role in ocean observation and exploration. Raman spectroscopy has a great advantage in simultaneous multiple species detection and is thus regarded as a favorable choice for ocean application. However, its sensitivity remains insufficient, and a demand in The detection of dissolved gases in seawater plays an important role in ocean observation and exploration. Raman spectroscopy has a great advantage in simultaneous multiple species detection and is thus regarded as a favorable choice for ocean application. However, its sensitivity remains insufficient, and a demand in enhancements is called!for before putting Raman spectroscopy to actual use in marine studies In this work, we developed a near-concentric cavity, in which laser beam could be trapped and reflected back and forth, for the purpose of intensifying Raman signals. The factors that would influence Raman signals were taken into account. The result show that the smaller angle between collection direction and optical axis of reflection mirror, the stronger the signal and signal to noise ratio (SNR) is. With a collection angle of 30°, our Near-concentric Cavity System managed to raise the SNR to a figure about 16 times larger than that of common methods applying 90°. Moreover, the alignment pattern in our system made it possible to excel concentric cavity with a 3 times larger SNR. Compared with the single-pass Raman signal, the signal intensity of our near-concentric cavity was up to 70 times enhanced. According to the obtained results of CO2 measurement, it can be seen that the new system provides a limit of detection(LOD) for CO2 about 0.19 mg·L-1 using 3-σ criterion standard, and the LOD of 11.5 μg·L-1 for CH4 was evaluated with the theoretical cross section values of CO2 and CH4..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 645 (2015)
Feasibility Study on Quantitative Analysis of Sulfide Concentration and pH of Marine Sediment Pore Water via Raman Spectroscopy
TIAN Zhi-xian, ZHANG Xin, LIU Chang-ling, MENG Qing-guo, and YAN Jun
Marine sediment pore water is one of the important objects in the study of global environmental change, marine geology and biogeochemistry. Anoxic pore water in highly reducing deep-sea sediments commonly contains a large amount of dissolved sulfide (H2S and HS-). The sulfide species within sediment pore water are signMarine sediment pore water is one of the important objects in the study of global environmental change, marine geology and biogeochemistry. Anoxic pore water in highly reducing deep-sea sediments commonly contains a large amount of dissolved sulfide (H2S and HS-). The sulfide species within sediment pore water are significant not only because the importance of themselves, but also because they exist as a function of pH which is another key parameter in pore water study. As degassing and chemical equilibrium altering are both inevitable, concentrations of sulfide species and pH value of marine sediment pore water acquired with traditional non-in situ technologies are of great uncertainty, and cannot represent the real geochemistry information. However, the recent deployment of an in situ laser Raman pore water sampler allows us to observe spectral sulfide signals of marine sediments in situ and in real time, which provide us a new technique to solve this problem. Sulfide species in water have a relatively strong Raman signal, which often appears in the form of a characteristic overlapping peak between 2 550~2 620 cm-1 and can be decomposed into HS- at 2 572 cm-1 and H2S at 2 592 cm-1. In the present paper, quantitative analysis of H2S and HS- with Raman spectroscopy is proved practicable and the accuracy is good. The pH of pore water is an important influencing factor of the diagenetic processes. As H2S and HS- are conjugate acid-base pairs, sulfide species within pore water exist as a function of pH and their concentration ratio depend on pH. This relationship is also shown in the Raman spectrum. To formulate the pore water pH calculation, sulfide solutions with pH range from 6.11 to 13.05 were prepared and their Raman spectra were observed. It is verified that the morphology of overlapping peaks change regularly with pH values. This phenomenon provides us the possibility of measuring the pH of pore water in situ via Raman spectroscopy. Based on peaks decomposition and correlativity analysis, we propose here a novel in situ pH measuring method for sediment pore water containing sulfide. This method can be used to measure the pH of pore water when the overlapping peak of sulfide is resolvable. The application scope of this pH measuring method in this study is 6.11~8.32, which covers almost all pH value of marine sediment pore water already known. The study provides additional technical reference for obtaining high-fidelity information of marine sediment pore water..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 649 (2015)
Studies on Effect of Alkali Pretreatment on Anaerobic Digestion of Rice Straw with Confocal Raman Microscopy
XIA Yi-hua, LUO Liu-bin, LI Xiao-li, HE Yong, and SHENG Kui-chuan
NaOH pretreatment is a convenient and effective method which is widely used in rice straw anaerobic digestion. But the mechanism of the alkaline (NaOH) hydrolysis of biopolymers compositions and polymeric cross-linked network structures of rice straw cell wall need further study. This paper firstly studied the effect aNaOH pretreatment is a convenient and effective method which is widely used in rice straw anaerobic digestion. But the mechanism of the alkaline (NaOH) hydrolysis of biopolymers compositions and polymeric cross-linked network structures of rice straw cell wall need further study. This paper firstly studied the effect and mechanism of alkali pretreatment on anaerobic digestion and biogas production of rice straw by using a combination of confocal Raman microscopy and transmission electron microscope. First, the original rice straw and the rice straw pretreated by NaOH were taken for mapping scanning by confocal Raman microscopy with micron-scale spatial resolution. Then principal component analysis was adopted to extract main information of Raman spectra, it could be found that the two types of samples were respectively presented with ray-like distribution in the first two principal component space, which were with cumulative contribution of 99%. And there was a clear boundary between the two types of samples without any overlapping, indicating that there was a significant difference of Raman spectral characteristic between original rice leaf and rice leaf pretreated by NaOH. Further analysis of the loading weights of the first two principal components showed that the Raman peaks at 1 739, 1 508 and 1 094 cm-1 were the important bands, and these three Raman peaks were attributed to the scattering of hemicellulose, cellulose and lignin respectively. Following, chemical imaging analysis of hemicellulose, cellulose and lignin were achieved by combining these Raman peaks and microscopic image information. It could be found that the NaOH pretreatment resulted in a loss of dense spatial uniformity structure of tissue and great decreases of the contents of these three ingredients, particularly lignin. It can be concluded that it is feasible to non-destructively measure hemicellulose, lignin and cellulose in rice straw tissue by confocal Raman microscopy, and to achieve chemical imaging analysis of the three ingredients in tissue, and this research will be much help for revealing the promotion mechanism of NaOH pretreatment for the rice straw fermentation and biogas production..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 657 (2015)
The Influence of Runoff Pollution to DOM Features in an Urban Wastewater Treatment Plant
HE Li, JI Fang-ying, LAI Ming-sheng, XU Xuan, ZHOU Wei-wei, MAO Bo-lin, and YANG Ming-jia
Combined with wastewater treatment process, the sewage in sunny and rainy day was collected from a wastewater treatment plant in Chongqing. Three-dimensional fluorescence spectra was used to investigate the characteristic fluorescence of dissolved organic matter (DOM). DOM dissolved organic carbon (DOC), chemical oxygeCombined with wastewater treatment process, the sewage in sunny and rainy day was collected from a wastewater treatment plant in Chongqing. Three-dimensional fluorescence spectra was used to investigate the characteristic fluorescence of dissolved organic matter (DOM). DOM dissolved organic carbon (DOC), chemical oxygen demand (COD), fluorescence index (f450/500) and fluorescence intensity ratio r(A, C) of fulvic acid in ultraviolet and visible region were used to analyze the impact of rain runoff pollution on sewage DOM. According to the experimental data, the DOM fluorescence fingerprints of this wastewater treatment plant were quite different from typical municipal sewage, and the main component was tryptophan with low excitation wavelength (Peak S), then the tryptophan with long wavelength excitation (Peak T) followed. A2/O process had an approximative degradation of the protein-like both in sunny day and rainy day, but had a better degradation of fulvic-like, DOC and COD in rainy day than that in sunny day. Morever, the fluorescence peaks got red-shifted after the biological treatment. The differences of DOM fluorescence fingerprint between sunny and rainy day were significant, the fluorescence center of UV fulvic (Peak A) in rainy day getting blue-shifted obviously, shifting from 240～248/390～440 to 240～250/370～400 nm. Although the DOM types in sunny and rainy day were the same, the source of fulvic got more complex by runoff and the component ratio of DOM also changed. Compared with the sunny day, the proportion of Peak S in DOM dereased by 10%, and the proportion of Peak A increased by 7% in rainy day..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 663 (2015)
Secondary Alterations Influence on Fluorescence Color and Spectral Parameters of Crude Oil and Oil Inclusion
SU Ao, CHEN Hong-han, and PING Hong-wei
Based on oil samples and rock samples in several petroliferous basins, this paper studied that secondary alterations influence on fluorescence color and spectral parameters of crude oil and oil inclusions by using microscopic fluorescent spectral and geochemical parameters. The results demonstrated that secondary alterBased on oil samples and rock samples in several petroliferous basins, this paper studied that secondary alterations influence on fluorescence color and spectral parameters of crude oil and oil inclusions by using microscopic fluorescent spectral and geochemical parameters. The results demonstrated that secondary alterations influence on spectral parameters by changing the ratio of saturated hydrocarbon and aromatic hydrocarbon(saturation/aromatics). Biodegradation and water washing lead to redshift of fluorescence parameters while evaporative fractionation and oil cracking lead to blueshift. Beside, mixed oil lead to redshift and blueshift. The secondary alterations and main period of accumulation in research area were recognized by frequency histogram of crude oil and oil inclusion. The relationship between QF-535 and the parameters measuring the secondary alterations could the extent of secondary alterations from which crude oil suffered. In the microscopic fluorescence test, oil inclusions suffered from stretch or leakage, thermal cracking and photooxidation should be rejected..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 668 (2015)
Quantum Chemistry Calculation of Ponceau 4R Molecule Structure and Research on the Fluorescence Mechanism
ZHU Chun, ZHANG Yong, WU Jian-chun, ZHU Tuo, and CHEN Guo-qing
The molecule structures of Ponceau 4R in ground state and the excited state were optimized by employing the Gaussian 09W program package. In addition, the electronic structure and frontier orbital of the ground state, the emission wavelength of the excited state was also investigated. And then, the Edinburgh FLS920P flThe molecule structures of Ponceau 4R in ground state and the excited state were optimized by employing the Gaussian 09W program package. In addition, the electronic structure and frontier orbital of the ground state, the emission wavelength of the excited state was also investigated. And then, the Edinburgh FLS920P fluorescence spectrometer was applied to the measurement of the fluorescence spectra of cochineal solution, and the emission spectra was obtained. The calculated emission wavelength had a good coincidence with the experiment data, which indicates that the optimized structures mentioned above are reasonable. The structures comparison between the ground state and the excited state was also performed to analyze the mechanism of fluorescence spectrum. It can be concluded that the molecule structure of excited state is nearly planar, so Ponceau 4R is thought to have strong fluorescent characteristics, the emission fluorescence is the result of transition from orbit 139 to orbit 137..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 674 (2015)
Investigation on Inhibitory Capacities of Seventeen Herbal Extracts on Oxidative Stress using Ultraviolet and Fluorescence Spectroscopy
HOU Guang-yue, ZHENG Zhong, SONG Feng-rui, LIU Zhi-qiang, and ZHAO Bing
Diabetic patients usually suffer from complications and the long-term secondary complications are the main cause of morbidity and mortality. The hyperglycemia-induced oxidative stress is one of the important pathogenesis of diabetic complications, while the oxidative stress is associated with the lipid peroxidation reaDiabetic patients usually suffer from complications and the long-term secondary complications are the main cause of morbidity and mortality. The hyperglycemia-induced oxidative stress is one of the important pathogenesis of diabetic complications, while the oxidative stress is associated with the lipid peroxidation reaction and the formation of advanced glycation end products (AGEs). Our study was focus on the pathogenesis of diabetic complications and based on the oxidative stress reaction. In this research, the oxidative stress inhibiting effects of seventeen herbal extracts were studied based on spectroscopic methodology. The capacities of herbal extracts against the lipid peroxidation reaction of rat liver in vitro were investigated using spectrophotometric method. It showed that the inhibitory activity of Radix Scutellariae and Flos Sophorae Immaturus were better than other herbal extracts. Additionally, the herbal extracts rich in flavonoids, alkaloids and lignanoids showed good inhibitory activities on the lipid peroxidation reaction. On the contrary, the saponin-rich herbal extracts possessed weak inhibitory effects. We applied the BSA/glucose (fructose) system combined with fluorescent spectroscopy to determine the inhibitory activities of herbal extracts in glycation model reactions. The results showed that the AGEs formation inhibitory activity of Flos Sophorae Immaturus, Radix Scutellariae and Rhizoma Anemarrhenae were better than others in the BSA/glucose (fructose) system by fluorescene analysis. The results demonstrated that the herbal extracts rich in flavonoids were found to be more effective than that of those herbal extracts as alkaloids and terpenoids class in inhibiting oxidative stress, while the saponin-rich herbal extracts showed weak inhibitory activities against oxidative stress. The Flos Sophorae Immaturus and Radix Scutellariae extracts had better inhibitory activity to the oxidative stress, so their pharmacological activity could be explored in further investigations. These results demonstrated in this assay could provide a reference for the study of pharmacological activity, and thus lays the foundation for the further study of the application of natural products in the prevention and treatment of diabetic complications..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 680 (2015)
A Fluorescent Chemical Sensor Based on MgAl-8-HQ LDH Composite Particle for the Selective Detection of Fe3+
YANG Lei, YAO Qi, YUAN Xue-hua, and YANG Yan-ling
In order to achieve the highly selective and Simple detection for ferric ion, strong-fluorescent 8-hydroxyquinoline(8-HQ) Mg-Al layered double hydroxide(MgχAl-8-HQ LDH) was designed and prepared by 8-HQ’s intercalation and ready coordination based on adjustment of Al3+ on Mg-Al layered double hydroxides(MgAl LDH) laminIn order to achieve the highly selective and Simple detection for ferric ion, strong-fluorescent 8-hydroxyquinoline(8-HQ) Mg-Al layered double hydroxide(MgχAl-8-HQ LDH) was designed and prepared by 8-HQ’s intercalation and ready coordination based on adjustment of Al3+ on Mg-Al layered double hydroxides(MgAl LDH) laminates. Meanwhile its structure and property were characterized by IR, XRD, UV-Vis and fluorescent spectrometer. IR analysis showed coordinate bonds of C-O-Al and C-N-Al between 8-HQ and Al3+ were generated. XRD revealed that 8-HQ had already inserted in MgAl LDH laminates, and it made (003) diffraction peaks move to low 2θ angle direction, and the diffraction peak intensity was enhanced with the molar ratio of Mg and Al increasing. Because the coordination reaction between 8-HQ and Al3+ in MgAl LDH laminates took place, it induced the absorption peak of 8-HQ at 314 nm disappeared, at the same time the transition absorption peak at 376 nm between metal ions and ligands appeared. As demonstrated by fluorescence spectroscopic analysis, fluorescence intensity of MgχAl-8-HQ LDH increased with the content of Al3+ reducing, when the molar ratio of Magnesium and Aluminium ion is 4∶1, its fluorescence intensity enhanced more significantly than 8-hydroxyquinoline aluminum. Through the research on the influence of metal ions on the fluorescence spectra of Mg4Al-8-HQ LDH particle, it was found that the particle to metal ions exhibited significant selection and difference, especially with high selectivity for Fe3+ ion. The effect of［Fe3+］ on the color and fluorescence intensity of Mg4Al-8-HQ LDH particle solution was further studied, and the results showed that the solution varied from light yellow to dark green with the content of Fe3+ in 10－6 to 10－2 mol·L-1 increasing, so it can implement colorimetric sensing for Fe3+ in the above range. And at the same time its fluorescence intensity significantly decreased, and its fluorescence could be completely quenched, when［Fe3+］ was 10－3 mol·L-1. When -log［Fe3+］ was in 3 to 6, negative correlation function appeared between -log［Fe3+］ and its fluorescence intensity, so it could implement fluorescence sensing detection for Fe3+ with high selectivity and sensitivity. According to the above research results, a new method of fluorescent and colorimetric dual sensor detection of Fe3+ by Mg4Al-8-HQ LDH particle was successfully established..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 684 (2015)
Rapid Identification of Cistanche via Fluorescence Spectrum Imaging Technology Combined with Principal Components Analysis and Fisher Distinction
LI Yuan-peng, HUANG Fu-rong, DONG Jia, XIAO Chi, XIAN Rui-yi, MA Zhi-guo, and ZHAO Jing
In order to explore rapid reliable Hebra cistanche detection methods, identification of 3 different sources of Hebra cistanche: cistanche deserticola, cistanche tubulosa, sand rossia is studied via fluorescent spectral imaging technology combined with pattern recognition. It is found in experiment that cistanche sampleIn order to explore rapid reliable Hebra cistanche detection methods, identification of 3 different sources of Hebra cistanche: cistanche deserticola, cistanche tubulosa, sand rossia is studied via fluorescent spectral imaging technology combined with pattern recognition. It is found in experiment that cistanche samples have obvious fluorescence properties. Forty fluorescence spectral images of 3 different sources of Hebra cistanche samples are collected through fluorescent spectral imaging system. After carrying on denoising and binarization processing to these images, the spectral curves of each sample was drawn according to the spectral cube. The obtained spectra data in the 450～680 nm wavelength range is regarded as the study object of discriminant analysis. Then, principal component analysis (PCA) is applied to reduce the dimension of spectroscopic data of the three kinds of cistanche and fisher distinction is used in combination to classify them; During the experiment were compared the effects of three methods of data preprocessing on the model: multiplicative scatter correction (MSC), standard normal variable correction (SNV) and first-order differential (FD) and then according to the cumulative contribution rate of the principal component and the effect of number of factors on the discriminant model to optimize the number of principal components factor. The results showed that: identification of the best after the first derivative pretreatment then the first four principal components is extracted to carry on fisher discriminant, discriminant model of 3 different sources of Hebra cistanche is set up through PCA combined with fisher discriminant the precision of original discrimination is 100%, recognition rate of the cross validation is 95%. It was thus shown that the fluorescent spectral imaging technology combined with principal components analysis and fisher distinction can be used for the identification study of 3 different sources of Hebra cistanche and has the advantages of easy operation, speediness, reliability..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 689 (2015)
Contrastive Research of the Y3Al5O12:Ce3+ Yellow Phosphors Prepared by Different Methods
LI Zhao, ZHAO Xi-cheng, CHEN Li-jun, JIANG Yuan-ru, and LUO Lei
Ce3+ doped Y3Al5O12∶Ce3+ yellow phosphors are prepared by the high-temperature solid-state method, sol-gel method and hydrothermal-pyrolysis methods. The influences of the preparation methods on the phase, morphology and photoluminescence properties of the YAG∶Ce3+ yellow phosphors are investigated by XRD, FESEM and PLCe3+ doped Y3Al5O12∶Ce3+ yellow phosphors are prepared by the high-temperature solid-state method, sol-gel method and hydrothermal-pyrolysis methods. The influences of the preparation methods on the phase, morphology and photoluminescence properties of the YAG∶Ce3+ yellow phosphors are investigated by XRD, FESEM and PL, respectively. The results indicate that the three methods all realize the substitution of Ce3+ ions for Y3+ ions, and that the cubic crystalline structure of the Ce3+-doped YAG phosphors is unchanged. The samples prepared by the high-temperature solid-state method present an irregular sphere-like morphology, with a large sample size; the sol-gel method produces nanoparticles with a notable particle agglomeration; and the samples prepared by the hydrothermal-pyrolysis method present a well-distributed sphere-like structure with a diameter of 10 μm. According to the fluorescence spectrum, the three samples are excited by blue light with a wavelength of 460 nm, and a big broadband emission at 550 nm is observed. However, due to the differences in the morphology and size, these samples present very different luminous intensities and quantum efficiencies..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 695 (2015)
The Effect of Observation Geometry on Polarized Skylight Spectrum
ZHANG Ren-bin, WANG Ling-mei, GAO Jun, and WANG Chi
Study on polarized skylight spectral characters while observation geometry changing in different solar zenith angles (SZA), viewing zenith angles (VZA) or relative azimuth angles (RAA). Simulation calculation of cloudless daylight polarimetric spectrum is realized based on the solver, vector discrete ordinate method, oStudy on polarized skylight spectral characters while observation geometry changing in different solar zenith angles (SZA), viewing zenith angles (VZA) or relative azimuth angles (RAA). Simulation calculation of cloudless daylight polarimetric spectrum is realized based on the solver, vector discrete ordinate method, of radiative transfer equation. In the Sun’s principal and perpendicular plane, the spectral irradiance data, varying at wavelengths in the range between 0.4 and 3 μm, are calculated to extend the atmospheric polarization spectral information under the conditions: the MODTRAN solar reference spectrum is the only illuminant source; the main influencing factors of polarized radiative transfer include underlying surface albedo, aerosol layers and components, and the absorption of trace gases. Simulation analysis results: (1) While the relative azimuth angle is zero, the magnitude of spectrum U/I is lower than 10-7 and V/I is negligible, the degree of polarization and the spectrum Q/I are shaped like the letter V or mirror-writing U. (2) In twilight, when the Sun is not in FOV of the detector, the polarization of the daytime sky has two maximum near 0.51 and 2.75 μm, and a minimum near 1.5 μm. For arbitrary observation geometry, the spectral signal of V/I may be ignored. According to observation geometry, choosing different spectral bands or polarized signal will be propitious to targets detection..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 700 (2015)
Study on Chemical Kinetic Effect of Dielectric Barrier Discharge Plasma
ZHANG Peng, HONG Yan-ji, SHEN Shuang-yan, DING Xiao-yu, and MA Di
To reveal the mechanism of plasma (assisted the ignition process of methane/air further, schematic of dielectric barrier discharge plasma system with atmospheric air was designed and set up, the emission spectrum of dielectric barrier discharge plasma with atmospheric air was measured, and the active particles producedTo reveal the mechanism of plasma (assisted the ignition process of methane/air further, schematic of dielectric barrier discharge plasma system with atmospheric air was designed and set up, the emission spectrum of dielectric barrier discharge plasma with atmospheric air was measured, and the active particles produced by the interaction of dielectric barrier discharge plasma with atmospheric air were analyzed with the spectrum technology, the ignition model and calculation methods of sensitivity analysis and reaction path analysis were given, effects of NO and O3 on the ignition delay time were simulated, and the chemical kinetics mechanism of NO andO3 assisted ignition was revealed via sensitivity analysis and reaction path analysis. The results show that main excited particles of N2 and O3 are generated via effect of plasma on the atmospheric air, which are converted into active particles of NOx and O3 in the end, the life of which are longer than any other active particles, effects of plasma on the ignition is simplified as effects of NOx and O3 on the ignition; NO and O3 could reduce the ignition delay time significantly, but the amplitude decrease with increase of the initial temperature, this is because the rate of ignition is decided by the oxidation rate of CH3, the oxidized pathway of CH3 is R155 and R156 for auto-ignition and their rates are slower when temperature is low, so the ignition delay time of methane/air is longer; NO could reduce the ignition delay time significantly because of the oxidized pathway of CH3 is changed to R327 CH3O2+NO=CH3O+NO2, R328 CH3+NO2=CH3O+NO for NOx(assisted ignition process from R155 and R156 for auto-ignition; and the chemical kinetic effect is the dominating factor of O3 on the ignition and which change the reaction path..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 706 (2015)
Effect of Helium on Diamond Films Deposited Using Microwave PCVD
CAO Wei, MA Zhi-bin, TAO Li-ping, GAO Pan, LI Yi-cheng, and FU Qiu-ming
Optical emission spectroscopy (OES) was used to in situ diagnose the CH4-H2-He plasma in order to know the effect of helium on the diamond growth by microwave plasma chemical vapor deposition (MPCVD). The spatial distribution of radicals in the plasma as a function of helium addition was studied. The diamond films depoOptical emission spectroscopy (OES) was used to in situ diagnose the CH4-H2-He plasma in order to know the effect of helium on the diamond growth by microwave plasma chemical vapor deposition (MPCVD). The spatial distribution of radicals in the plasma as a function of helium addition was studied. The diamond films deposited in different helium volume fraction were investigated using scanning electron microscope (SEM) and Raman spectroscopy. The results show that the spectra intensity of radicals of Hα, Hβ, Hγ, CH and C2 increases with the increasing of helium volume fraction, especially, that of radical Hα has the most improvement. The spectrum space diagnosis results show that the uniformity of C2, CH radicals in the plasma tends to poor due to the helium addition and resulted in a different thickness along the radial direction The measurement of deposition rate shows that the addition of helium is useful for the improvement of the growth rate of diamond films, due to relative concentration of carbon radicals was increased. The deposition rate increases by 24% when the volume fraction of He was increased from 0 vol.% to 4.7 vol.%. The micrographs of SEM reveal that with the increasing of helium volume fraction, the diamond films’ crystallite orientation changes from (111) to disorder and a twins growth becomes obvious. The secondary nucleation density during growth increases because the high relatively concentration of C2 radicals under higher helium volume fraction (4.7vol. %). In addition, the substrate was etched and sputtered by the plasma, which introduced metallic atoms into the plasma during the deposition of diamond films. Eventually, the existing of secondary nucleation and impurity atoms lead to the appearance of twins and results in the compressive dress..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 711 (2015)
Estimation and Visualization of Nitrogen Content in Citrus Canopy Based on Two Band Vegetation Index (TBVI)
WANG Qiao-nan, YE Xu-jun, LI Jin-meng, XIAO Yu-zhao, and HE Yong
Nitrogen is a necessary and important element for the growth and development of fruit orchards. Timely, accurate and nondestructive monitoring of nitrogen status in fruit orchards would help maintain the fruit quality and efficient production of the orchard, and mitigate the pollution of water resources caused by excesNitrogen is a necessary and important element for the growth and development of fruit orchards. Timely, accurate and nondestructive monitoring of nitrogen status in fruit orchards would help maintain the fruit quality and efficient production of the orchard, and mitigate the pollution of water resources caused by excessive nitrogen fertilization. This study investigated the capability of hyperspectral imagery for estimating and visualizing the nitrogen content in citrus canopy. Hyperspectral images were obtained for leaf samples in laboratory as well as for the whole canopy in the field with ImSpector V10E (Spectral Imaging Ltd., Oulu, Finland). The spectral datas for each leaf sample were represented by the average spectral data extracted from the selected region of interest (ROI) in the hyperspectral images with the aid of ENVI software. The nitrogen content in each leaf sample was measured by the Dumas combustion method with the rapid N cube (Elementar Analytical, Germany). Simple correlation analysis and the two band vegetation index (TBVI) were then used to develop the spectra data-based nitrogen content prediction models. Results obtained through the formula calculation indicated that the model with the two band vegetation index (TBVI) based on the wavelengths 811 and 856 nm achieved the optimal estimation of nitrogen content in citrus leaves (R2=0.607 1). Furthermore, the canopy image for the identified TBVI was calculated, and the nitrogen content of the canopy was visualized by incorporating the model into the TBVI image. The tender leaves, middle-aged leaves and elder leaves showed distinct nitrogen status from highto low-levels in the canopy image. The results suggested the potential of hyperspectral imagery for the nondestructive detection and diagnosis of nitrogen status in citrus canopy in real time. Different from previous studies focused on nitrogen content prediction at leaf level, this study succeeded in predicting and visualizing the nutrient content of fruit trees at canopy level. This would provide valuable information for the implementation of individual tree-based fertilization schemes in precision orchard management practices..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 715 (2015)
Optical Constants Determination of Zinc Selenide by Inversing Transmittance Spectrogram Transmittance Spectra Measurement and Thermal Radiative Physical Parameters Inversion of Diesel Fuel
LI Dong, QI Han-bing, and WU Guo-zhong
A novel inversion method of optical constants of diesel fuel that is one of semitransparent liquid was developed based on spectral transmittance radio inversion calculation of optical cell with glass-liquid fuel-glass configuration, which was validated by measured the optical constants of water. The measurements of traA novel inversion method of optical constants of diesel fuel that is one of semitransparent liquid was developed based on spectral transmittance radio inversion calculation of optical cell with glass-liquid fuel-glass configuration, which was validated by measured the optical constants of water. The measurements of transmittance spectrogram of optical cell filled with diesel fuel in the infrared wavelength 2~15 μm at normal incidence were investigated by Bruke V70 FTIR spectrometer. The optical constants and thermal radiative physcial parameters of diesel fuel were achieved. The results show that, (1) The optical constants of water determined by the new method (IDTM) have good agreement with previously data sets. (2) The optical constants calculation precision of the IDTM is similar with MCDTM, which is higher than SODTM and SDTM. (3) The transmittance capability of diesel fuel in the infrared wavelength 2~15 μm are weak, and there exist five absorption peaks, which are respectively 2.4, 3.4, 6.2, 7.3 and 13.8 μm. (4) The spectral selectivity of optical constants and thermal radiative physcial parameters of diesel fuel are stronger, whose values are urgently varied with different wavelenths..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 719 (2015)
Monitoring of Crack Propagation in Repaired Structures Based on Characteristics of FBG Sensors Reflecting Spectra
YUAN Shen-fang, JIN Xin, QIU Lei, and HUANG Hong-mei
In order to improve the security of aircraft repaired structures, a method of crack propagation monitoring in repaired structures is put forward basing on characteristics of Fiber Bragg Grating(FBG) reflecting spectra in this article. With the cyclic loading effecting on repaired structure, cracks propagate, while non-In order to improve the security of aircraft repaired structures, a method of crack propagation monitoring in repaired structures is put forward basing on characteristics of Fiber Bragg Grating(FBG) reflecting spectra in this article. With the cyclic loading effecting on repaired structure, cracks propagate, while non-uniform strain field appears nearby the tip of crack which leads to the FBG sensors’ reflecting spectra deformations. The crack propagating can be monitored by extracting the characteristics of FBG sensors’ reflecting spectral deformations. A finite element model (FEM) of the specimen is established. Meanwhile, the distributions of strains which are under the action of cracks of different angles and lengths are obtained. The characteristics, such as main peak wavelength shift, area of reflecting spectra, second and third peak value and so on, are extracted from the FBGs’ reflecting spectral which are calculated by transfer matrix algorithm. An artificial neural network is built to act as the model between the characteristics of the reflecting spectral and the propagation of crack. As a result, the crack propagation of repaired structures is monitored accurately and the error of crack length is less than 0.5 mm, the error of crack angle is less than 5 degree. The accurately monitoring problem of crack propagation of repaired structures is solved by taking use of this method. It has important significance in aircrafts safety improvement and maintenance cost reducing..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 724 (2015)
Synthesis and Characterization of PAM Derivative Weak Gel
WANG Xiao-nan, and YU Pei-zhi
Weak gel with PAM cross-linked radical reaction was prepared by being incorporated to side chain of PAM. The structure, gel for ming process and the influence of NaCl concentration to apparentviscosity of gel were studied. The results show that the crosslinking ratios influence to crosslinking time, gel breaking time aWeak gel with PAM cross-linked radical reaction was prepared by being incorporated to side chain of PAM. The structure, gel for ming process and the influence of NaCl concentration to apparentviscosity of gel were studied. The results show that the crosslinking ratios influence to crosslinking time, gel breaking time and gel strength. The crosslinking time decreases and gel strength slightly increases with increase of crosslinking ratio. Apparent viscosity of Polyacrylamide derivative crosslinking system increases with increase of NaCl concentration. The weak gel has good salt tolerance ability..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 730 (2015)
Mixed-Spectral Spatial Information Decomposition Model of Water Hyperspectral Inversion
PAN Bang-long, WANG Xian-hua, ZHU Jin, YI Wei-ning, and FANG Ting-yong
The effect of Mixed-hyperspectral in the water is difficult in quantitative remote sensing of water. Studies have shown that the only scalar spectrum information is difficult to solve the problem of complex mixed spectra of water. Besides the spectral information, spatial distribution of information is one of the obvioThe effect of Mixed-hyperspectral in the water is difficult in quantitative remote sensing of water. Studies have shown that the only scalar spectrum information is difficult to solve the problem of complex mixed spectra of water. Besides the spectral information, spatial distribution of information is one of the obvious characteristics of the broad waters pollution, and can be used as a useful complement to the remote sensing information and facilitate water complex spectral unmixing. Taking Chaohu as an example, the paper applies the HJ-1A HSI hyperspectral data and the supplemental surface spectral measurement data to discuss the mixed spectra of lake water by spatial statistics and genetic algorithm theory. By using the spatial variogram of geostatistics to simulate the distribution difference of two adjacent pixels, the space-informational decomposition model of mixed spectral in lake water is established by co-kriging genetic algorithm, which is a improved algorithm applying the spatial variogram function of neighborhood pixel as the constraint of the objective function of the genetic algorithm. Finally, the model inversion results of suspended matter concentration are verified. Compared with the conventional spectral unmixing model, the results show the correlation coefficient of the predicted and measured value of suspended sediment concentration is 0.82, the root mean square error 9.25 mg·L-1 by mixed spectral space information decomposition model, so the correlation coefficient is increased by 8.9%, the root mean square error reduced by 2.78 mg·L-1, indicating that the model of suspended matter concentration has a strong predictive ability. Therefore, the effective combination of spatial and spectral information of water, can avoid inversion result distortion due to weak spectral signal of water color parameters, and large amount of calculation of information extraction because of the high spectral band numbers, and also provides an effective way to solve spectral mixture model of complex water and improve the accuracy of model inversion..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 734 (2015)
Estimating Biomass Burned Areas from Multispectral Dataset Detected by Multiple-Satellite
YU Chao, CHEN Liang-fu, LI Shen-shen, TAO Jin-hua, and SU Lin
Biomass burning makes up an important part of both trace gases and particulate matter emissions, which can efficiently degrade air quality and reduce visibility, destabilize the global climate system at regional to global scales. Burned area is one of the primary parameters necessary to estimate emissions, and considerBiomass burning makes up an important part of both trace gases and particulate matter emissions, which can efficiently degrade air quality and reduce visibility, destabilize the global climate system at regional to global scales. Burned area is one of the primary parameters necessary to estimate emissions, and considered to be the largest source of error in the emission inventory.Satellite-based fire observations can offer a reliable source of fire occurrence data on regional and global scales, a variety of sensors have been used to detect and map fires in two general approaches: burn scar mapping and active fire detection. However, both of the two approaches have limitations. In this article, we explore the relationship between hotspot data and burned area for the Southeastern United States, where a significant amount of biomass burnings from both prescribed and wild fire took place.MODIS (Moderate resolution imaging spectrometer) data, which has high temporal-resolution, can be used to monitor ground biomass burning in time and provided hot spot data in this study. However, pixel size of MODIS hot spot can’t stand for the real ground burned area. Through analysis of the variation of vegetation band reflectance between pre- and post-burn, we extracted the burned area from Landsat-5 TM (Thematic Mapper) images by using the differential normalized burn ratio (dNBR) which is based on TM band4 (0.84 μm) and TM band 7(2.22 μm) data. We combined MODIS fire hot spot data and Landsat-5 TM burned scars data to build the burned area estimation model, results showed that the linear correlation coefficient is 0.63 and the relationships vary as a function of vegetation cover. Based on the National Land Cover Database (NLCD), we built burned area estimation model over different vegetation cover, and got effective burned area per fire pixel, values for forest, grassland, shrub, cropland and wetland are 0.69, 1.27, 0.86, 0.72 and 0.94 km2 respectively. We validated the burned area estimates by using the ground survey data from National Interagency Fire Center (NIFC), our results are more close to the ground survey data than burned area from Global Fire Emissions Database(GFED) and MODIS burned area product (MCD45), which omitted many small prescribed fires. We concluded that our model can provide more accurate burned area parameters for developing fire emission inventory, and be better for estimating emissions from biomass burning..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 739 (2015)
Application of Hyperspectral Imaging for Visualization of Nitrogen Content in Pepper Leaf with Different Positions
YU Ke-qiang, ZHAO Yan-ru, LI Xiao-li, DING Xi-bin, ZHUANG Zai-chun, and HE Yong
In order to estimate pepper plant growth rapidly and accurately, hyperspectral imaging technology combined with chemometrics methods were employed to realize visualization of nitrogen content (NC) distribution. First, pepper leaves were picked up with the leaf number based on different leaf positions, and hyperspectralIn order to estimate pepper plant growth rapidly and accurately, hyperspectral imaging technology combined with chemometrics methods were employed to realize visualization of nitrogen content (NC) distribution. First, pepper leaves were picked up with the leaf number based on different leaf positions, and hyperspectral data of these leaves were acquired. Then, SPAD and NC value of leaves were measured, respectively. After acquirement of pepper leaves’ spectral information, random-frog (RF) algorithm was chosen to extract characteristic wavelengths. Finally, five characteristic wavelengths were selected respectively, and then those characteristic wavelengths and full spectra were used to establish partial least squares regression (PLSR) models, respectively. As a result, SPAD predicted model had an excellent performance of RC=0.970, RCV=0.965, RP=0.934, meanwhile evaluation parameters of NC predicted model were RC=0.857, RCV=0.806, RP=0.839. Lastly, according to the optimal models, SPAD and NC of each pixel in hyperspectral images of pepper leaves were calculated and their distribution was mapped. In fact, SPAD in plant can reflect the NC. In this research, the change trend of both was similar, so the conclusions of this research were proved to be corrected. The results revealed that it was feasible to apply hyperspectral imaging technology for mapping SPAD and NC in pepper leaf, which provided a theoretical foundation for monitoring plant growth and distribution of nutrients..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 746 (2015)
Review of Extraordinary Optical Transmission: Theory and Application in Biochemical Analysis
TU Long, WANG Wen-hui, and QIU Zhi-chang
Extraordinary optical transmission (EOT) has attracted increasing attention from researchers around the world since its discovery in 1998. In attempt to interpret this abnormal phenomenon caused by nano-hole array structures, the majority of academia take the theory of surface plasmon resonance as the main reason, thouExtraordinary optical transmission (EOT) has attracted increasing attention from researchers around the world since its discovery in 1998. In attempt to interpret this abnormal phenomenon caused by nano-hole array structures, the majority of academia take the theory of surface plasmon resonance as the main reason, though minors resort to other theories. Nevertheless, significant amount of research has revealed the factors that are associated with EOT spectra. In particular, the association of molecules with the surface of the nano-hole array can be linearly related to the red-shifted change of EOT spectrum, lending EOT based nano-hole array a unique capability of detecting biochemical events. Such biochemical analysis is label-free, real-time, highly sensitive, promising great potentials in miniaturization of EOT-based advanced instrument. By summarizing the research progress, achievements, and trends of EOT, including its theory and application in biochemical analysis, this paper aims to provide reasonably-deep insights into this exciting area. To this end, EOT is firstly briefly introduced, followed by its physical mechanism and effects. Then recent advances in EOT-based biochemical analysis is presented, with a focus on three representative research teams. Finally, an outlook on the EOT-based biochemical analysis is given..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 751 (2015)
Determination of Silicon in Gasoline by Directly Measuring under Organic Phase Using Inductively Coupled Plasma Optical Emission Spectroscopy
ZHANG Wen-mei, WEN Huan, LV Huan-ming, LIU Hui-qin, LIN Zhi-sheng, and WANG Rong-hua
A simple and accurate method was developed for determining silicon in gasoline using inductively coupled plasma optical emission spectroscopy (ICP-OES). For sample inroduction a Burgener nubulizer and a Cyclonic spray chamber were used. A gasoline sample was diluted with isooctane and then introduced into the cooled spA simple and accurate method was developed for determining silicon in gasoline using inductively coupled plasma optical emission spectroscopy (ICP-OES). For sample inroduction a Burgener nubulizer and a Cyclonic spray chamber were used. A gasoline sample was diluted with isooctane and then introduced into the cooled spray chamber of the ICP-OES. Good linearity was achieved in the silicon concentration range 0.1～10.0 mg·kg-1, and the correlation coefficient was 0.999 96. The detection limit for silicon was 0.012 mg·kg-1 and the silicon recoveries from gasoline samples were 95.8%～98.4%, with relative standard deviations of less than 3.0%. The method was proved to be simple, reliable and highly sensitive, and suitable for determining silicon in samples of motor gasoline, ethanol-gasoline and methanol-gasoline fuel mixtures those containing not more than 15% (V/V) oxygenates..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 760 (2015)
Experimental Study of Coaxial Cylinder Dielectric Barrier Discharge in Ar/NH3 Mixtures under the Atmosphere-Pressure
LI Yan-qin, BU De-cai, DI Lan-bo, ZHANG Xiu-ling, LIU Zhi-sheng, and LI Xue-hui
An atmosphere-pressure Dielectric Barrier Discharge in Ar/NH3 mixtures between cylinder electrodes is studied by Optical Emission Spectroscopy and the main particles of atmosphere-pressure Ar/NH3 DBD plasma are NH, N, N+, N2, Ar, Hα and OH. NH is decomposition products of NH3, and NH(ｃ１Π) and NH(Ａ３Π) are two kinds of eAn atmosphere-pressure Dielectric Barrier Discharge in Ar/NH3 mixtures between cylinder electrodes is studied by Optical Emission Spectroscopy and the main particles of atmosphere-pressure Ar/NH3 DBD plasma are NH, N, N+, N2, Ar, Hα and OH. NH is decomposition products of NH3, and NH(ｃ１Π) and NH(Ａ３Π) are two kinds of excited-state neutral particles and produced by penning ionization of Ar* and NH3. The nitrogen active atom is detected at 674.5 nm which may provide the experimental foundation for the synthesis of ε-Fe3N ferroparticles by the atmosphere-pressure Ar/NH3 DBD plasma. The intensities of main particles are analyzed at different NH3 flow rate and applied voltage peak-peak value. The results show that the spectral line intensities of various particles increase with the rise of the applied voltage peak-peak value at the same NH3 flow rate, and first increase and then decrease with the increase of the NH3 flow rate at the same applied voltage peak-peak value. The applied voltage peak-peak value being kept constant, the spectral line intensity of nitrogen active atom first increases and then decreases with the increase of the NH3 flow rate. When NH3 flow rate is 20 mL·min-1, the spectral line intensity of nitrogen active atom reaches a maximum at the same applied voltage peak-peak value. The spectral line intensity of nitrogen active atom decreases gradually with increasing the applied voltage peak-peak value at the same NH3 flow rate and it is mainly because of the translation of discharge mode from multi-pulse APGD to filamentary discharge in the atmosphere-pressure Ar/NH3 DBD. The microdischarge channels overlap and the microdischarges affect each other in multi-pulse APGD; hence the increasing rate of the spectral line intensity is quicker in multi-pulse APGD than in filamentary discharge with increasing the applied voltage peak-peak value. When the applied voltage peak-peak value is up from 4 600 to 6 400 V, the single-pulse and two-pulse APGD mode which are two kinds of homogeneous DBD mode are found in the atmosphere-pressure Ar/NH3 DBD and the increasing rate of the spectral line intensity is quicker in multi-pulse APGD than in filamentary discharge which is beneficial to synthesize ε-Fe3N ferroparticles..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 765 (2015)
A Study on Quantitative Evaluation of Damage in Conservation of Ceramics from HuaguangjiaoⅠShipwreck with ICP-AES
LI Wen-jing, CHEN Yue, LI Nai-sheng, LI Bin, and LUO Wu-gan
ICP-AES was used to determine the elemental composition of solutions in different conservation steps for understanding the impact of cleaning agents on ceramics from HuaguangjiaoⅠshipwreck. The results showed that high content in solution of Al, Fe, Mg ions, which can be indexes to reflect the damage in conservation ofICP-AES was used to determine the elemental composition of solutions in different conservation steps for understanding the impact of cleaning agents on ceramics from HuaguangjiaoⅠshipwreck. The results showed that high content in solution of Al, Fe, Mg ions, which can be indexes to reflect the damage in conservation of ceramics. According to these indexes, we discovered that agents of strong cleaning ability bring more damage to ceramic samples. Meanwhile, the state of preservation of the ceramics was closely related to the damage in conservation. Ceramics in an excellent state of preservation endure less damage than that in bad state. We also found that each cleaning agent cause certain degree of damage on porcelains, even neutral reagent, like deionized water. Moreover, moderate cleaning reagent, when using a long time, bring the same degree of damage as the strong acid. Therefore, in actual protection procedure, for conservation ceramics safe and effective, damage of each cleaning agents and cumulative damage should be considered..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 772 (2015)
Determination of Acid-Insoluble Aluminum Content in Steel by Laser-Induced Breakdown Spectroscopy
YANG Chun, JIA Yun-hai, and ZHANG Yong
Laser-induced breakdown spectroscopy (LIBS) has become a very attractive and popular chemical analysis technique in material science for its advantage of rapid analysis, non-contact measurement, micro surface analysis and online analysis. In this paper, LIBS were used to determine insoluble aluminum content by analyzinLaser-induced breakdown spectroscopy (LIBS) has become a very attractive and popular chemical analysis technique in material science for its advantage of rapid analysis, non-contact measurement, micro surface analysis and online analysis. In this paper, LIBS were used to determine insoluble aluminum content by analyzing the scanning data on massive steel samples. Abnormal data were discarded by Nalimov criterion, and the remaining data was used to calculate the average and the standard deviation. The threshold to distinguish acid-insoluble aluminum and soluble aluminum was identified as the average value plus triple standard deviation. Two different mathematical models were proposed to calculate insoluble aluminum content, respectively according to the ratio of the total acid-insoluble aluminium signal strength to total aluminum signal strength and acid-insoluble signal number to total aluminum signal number. The total aluminum content was determined by the calibration curve. Insoluble aluminum content of certified reference materials and plate blank samples obtained by mathematical model is coincident to chemical wet method results. The result according to total acid-insoluble aluminium signal strength is much better. LIBS can be used as a rapid analysis method to characterize insoluble aluminum content in steel samples..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 777 (2015)
Quantitative Analysis of Copper Impurity in Silver Jewellery by Laser-Ablation Laser-Induced Breakdown Spectroscopy
CHEN Yu-qi, MO Jun-yu, ZHOU Qi, LOU Yang, and LI Run-hua
High spectral analysis sensitivity can be achieved with orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy under minimal sample ablation. Therefore, the contradiction between spatial resolution and analytical sensitivity existed in single-pulse laser-induced breakdown spectroscopyHigh spectral analysis sensitivity can be achieved with orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy under minimal sample ablation. Therefore, the contradiction between spatial resolution and analytical sensitivity existed in single-pulse laser-induced breakdown spectroscopy can be resolved fundamentally in this technique. In order to eliminate the influence of different experimental parameters to the signal intensities and final results of quantitative analysis, the correlation between copper atomic emission and silver atomic emission was studied experimentally in this technique for silver jewellery samples. It was demonstrated that the intensity of atomic emission of copper at 324.75 nm and that of silver at 328.07 nm was linearly correlated with high correlation coefficient. Therefore, it was possible to eliminate the influence of different experimental parameters, such as geometrical arrangement and pulse energy of the ablation laser to the signal of copper atomic emission by selecting 328.07 nm line of silver as internal standard. A quantitative analysis of copper impurity in silver jewellery can be realized by using orthogonal dual-wavelength dual-pulse laser-ablation laser-induced breakdown spectroscopy. A calibration curve of copper was successfully built based on internal standard method while selecting 328.07 nm line of silver as internal standard. The limit of detection of copper in silver matrix was determined to be 44 ppm in this technique when the crater’s diameter was about 17 μm under current experimental condition..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 782 (2015)
Experimental Conditions of Laser Induced Breakdown Spectroscopy of Metal Elements in Cement
WANG Rui-wen, LI Zhan-feng, WU Zhi-xiang, LI Wen-hong, and SHANG Li-ping
Laser induced breakdown spectroscopy (LIBS) is a widely used material element detection technology. Because of its detection result is affected by many factors, and therefore, analysing and comparising the different experimental conditions have important significance for LIBS. Experimental sample produced by Beichuan CLaser induced breakdown spectroscopy (LIBS) is a widely used material element detection technology. Because of its detection result is affected by many factors, and therefore, analysing and comparising the different experimental conditions have important significance for LIBS. Experimental sample produced by Beichuan County, Sichuan Province, China, which is ordinary Portland cement P.O42.5, using eight-channel fiber optic spectrometer AvaSpec-2048-USB2-RM, delay trigger DG645 for LIBS testing. Several metallic elements as Mg, Al, Na, K, which affect cement’s technical indicators were analyzed. Mainly compares the effect of laser frequency, the same point measurement times on different metal element spectral signal intensity, the optimum experimental parameters under the condition of this experiment: 10 Hz was the best laser frequency. When laser frequency is 10 Hz, the spectrum intensity of elements Mg, Al, Na, K were increased by 67.66%, 47.88%, 84.59%, 43.36% than 8 Hz. Because the tablet samples in place, the surface will have a small amount of oxidation and deliquescence, in order to measure 10 times for an average income results were recorded under the condition, with third, four records of results for the best..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 787 (2015)
The Emission Spectroscopy of Nitrogen Discharge under Low Voltage at Room Temperature
SHEN Li-hua, YU Chun-xia, YAN Bei, and ZHANG Cheng-xiao
A set of direct current(DC) discharge device of N2 plasma was developed, carbon nanotubes(CNT) modified ITO electrode was used as anode, aluminum plate as cathode, with ~80 μm separation between them. Nitrogen emission spectra was observed at room temperature and low DC voltage (less than 150 V), and the emission spectA set of direct current(DC) discharge device of N2 plasma was developed, carbon nanotubes(CNT) modified ITO electrode was used as anode, aluminum plate as cathode, with ~80 μm separation between them. Nitrogen emission spectra was observed at room temperature and low DC voltage (less than 150 V), and the emission spectrometry was used to diagnose the active species of the process of nitrogen discharge. Under DC discharge, the strongest energy band N2(C3Πu), the weak Gaydon’s Green system N2(H3Φu-G3Δg) and the emission line of nitrogen atoms (4p-4p0) at 820 nm were observed. Found that metastable state of nitrogen molecules were the main factors leading to a series of excited state nitrogen atoms and nitrogen ionization. Compared the emission spectra under DC with that under alternating current (AC) (1.1 kV), and it can be seen that under DC the spectra band of nitrogen atoms can be obviously observed, and there was a molecular band in the range of 500～800 nm. The effect of oxygen and hydrogen on the emission spectra of nitrogen was investigated. The results showed that the oxygen inhibited the luminescence intensity of nitrogen, but the shape of spectra unchanged. All of the second positive system, Gaydon’s Green system and atomic lines of nitrogen can be observed. The second positive system and Gaydon’s Green system of nitrogen will be greatly affected when the volume ratio of nitrogen and hydrogen greatly affected is 1∶1, which was due to the hydrogen. The hydrogen can depresse nitrogen plasma activation, and make the Gaydon’s Green System disappeared. CNT modified ITO electrode can reduce the breakdown voltage, and the optical signal generated by the weakly ionized gas can be observed by the photomultiplier tube at low voltage of 10 V..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 791 (2015)
In Situ Analysis of Element Geochemistry in Submarine Basalt in Hydrothermal Areas from Ultraslow Spreading Southwest Indian Ridge
WANG Yan, SUN Xiao-ming, XU Li, LIANG Ye-heng, WU Zhong-wei, FU Yu, and HUANG Yi
In this study, we analyze element geochemistry of submarine basalt in situ, which is sampled in hydrothermal areas from ultraslow spreading Southwest Indian Ridge, including the fresh basalt rocks (B19-9, B15-13) and altered basalt (B5-2). And we can confirm that altered mineral in B5-2 is celadonite by microscope and In this study, we analyze element geochemistry of submarine basalt in situ, which is sampled in hydrothermal areas from ultraslow spreading Southwest Indian Ridge, including the fresh basalt rocks (B19-9, B15-13) and altered basalt (B5-2). And we can confirm that altered mineral in B5-2 is celadonite by microscope and Raman Spectrum. Furthermore, amygdaloidal celadonites are analyzed by electron microprobe (EPMA) and EDS-line scanning. The results show that K-contents decrease and Na-contents increase from the core to the edge in these altered minerals, indicating the transition from celadonite to saponite. Celadonite is an altered minerals, forming in low temperature(<50 ℃) and oxidizing condition, while saponite form in low water/rock and more reducing condition. As a result, the transition from celadonite to saponite suggests environment change from oxidizing to reducing condition. Using the result of EPMA as internal standard, we can analyze rare earth elements (REE) in altered mineral in situ. Most of result show positive Eu anomaly (δEu), indicating hydrothermal fluid transform from oxidizing to reducing, and reducing fluid rework on the early altered minerals. Comparison with REE in matrix feldspar both in altered and unaltered zoning, we find that reducing fluid can leach REE from the matrix feldspar, leading to lower total REE concentrations and positive Eu anomaly. So leaching process play an important role in hydrothermal system..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 796 (2015)
Mineral Spectrum Change Analysis under the Conditions of Different Particle Size
WANG Yan-xia, WU Jian, ZHOU Liang-guang, HOU Lan-gong, WANG Dong, and CAO Min
Mineral particle size is an important factor affecting mineral spectrum characteristics, so to explore the changes of the mineral spectrum curves under different particle sizes and the spectrum difference of different minerals under the same particle size are the keys of hyperspectral remote sensing information mineralMineral particle size is an important factor affecting mineral spectrum characteristics, so to explore the changes of the mineral spectrum curves under different particle sizes and the spectrum difference of different minerals under the same particle size are the keys of hyperspectral remote sensing information mineral identification and the theoretical basis of research on spectral differences of different particle sizes. Six kinds of collected minerals were observed by spectrometer to get the reflectivity spectrum curve and first order differential spectral curve under different particle sizes, and the spectral characteristics of various kinds of minerals under different particle sizes were analyzed. At the same time, spectrum difference of different mineral under the same particle size was compared to explore possible wavelengths of hyperspectral remote sensing mineral identify. Results show that the spectrum curves of various minerals have a larger difference with the change of the particle size, but change law is not the same. The whole spectrum curve of hypersthene will be decreased with the increase of particle size, and the spectrum curve at a specific wavelength range of antigorite, hematite, kaolinite and chlorite will be decreased with the increase of particle size, and there is no direct correlation between the spectrum of olivine and the particle size. Under the same size, different mineral spectral reflectance change a lot in most band range and it provides the possibility for high precision identification of mineral. Antigorite, kaolinite and chlorite all have more absorption peaks of narrow width and smaller intensity than the other minerals. Spectrum curves of hematite, olivine and hypersthene are relatively smooth, and the number of the absorption and reflection peaks is relatively small. This study aims at providing basic data and theoretical support for mineral spectral library construction and mineral hyperspectral identification technology..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 803 (2015)
Evaluation of Field Portable X-Ray Fluorescence Performance for the Analysis of Ni in Soil
DU Guo-dong, LEI Mei, ZHOU Guang-dong, CHEN Tong-bin, and QIU Rong-liang
As a rapid, in-situ analysis method, Field portable X-ray fluorescence spectrometry (FP-XRF) can be widely applied in soil heavy metals analysis field. Whereas, some factors may affect FP-XRF performance and restrict the application. Studies have proved that FP-XRF has poorer performance when the concentration of targeAs a rapid, in-situ analysis method, Field portable X-ray fluorescence spectrometry (FP-XRF) can be widely applied in soil heavy metals analysis field. Whereas, some factors may affect FP-XRF performance and restrict the application. Studies have proved that FP-XRF has poorer performance when the concentration of target element is low, and soil moisture and particle size will affect FP-XRF performance. But few studies have been conducted in depth. This study took an example of Ni, demonstrated the relationship between Ni concentration and FP-XRF performance on accuracy and precision, and gave a critical value. Effects of soil moisture and particle size on accuracy and precision also had been compared. Results show that, FP-XRF performance is related to Ni concentration and the critical value is 400 mg·kg-1. Relative standard deviation (RSD) and relative uncertainty decrease while the Ni concentration is below 400 mg·kg-1, hence FP-XRF performance improves with increasing Ni concentration in this range; RSD and relative uncertainty change little while the Ni concentration is above 400 mg·kg-1, hence FP-XRF performance does not have correlation with Ni concentration any more. For in-situ analysis, the relative uncertainty contributed by soil moisture is 3.77%, and the relative certainty contributed by particle size is 0.56%. Effect of soil moisture is evidently more serious than particle size both on accuracy and precision..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 809 (2015)
Comporison Sduty of Microstructure by Metallographicalk on the Polarized Light and Texture by XRD of CC 5083 and CC 5182 Aluminium Alloy after Cold Rolling and Recrystallization
CHEN Ming-biao, LI Yong-wei, TAN Yuan-biao, MA Min, WANG Xue-min, and LIU Wen-chang
At present the study of relation between microstructure,texture and performance of CC 5083 aluminium alloy after cold tolling and recrystallization processes is still finitude. So that the use of the CC 5083 aluminium alloy be influenced. Be cased into electrical furnace, hot up with unlimited speed followed the furnacAt present the study of relation between microstructure,texture and performance of CC 5083 aluminium alloy after cold tolling and recrystallization processes is still finitude. So that the use of the CC 5083 aluminium alloy be influenced. Be cased into electrical furnace, hot up with unlimited speed followed the furnace hot up to different temperature and annealed 2h respectively, and be cased into salt-beth furnace, hot up quickly to different temperature and annealed 30min respectively for CC 5083 and CC 5182 aluminum alloy after cold roling with 91.5% reduction. The microstructure be watched use metallographic microscope, the texture be inspected by XRD. The start temperature of recrystallization and grain grow up temperature within annealing in the electric furnace of CC 5083 aluminum alloy board is 343 ℃, and the shap of grain after grow up with long strip (the innovation point ); The start temperature of recrystallization within annealling in the salt bath furnace of CC 5083 is 343 ℃. The start temperature and end temperature of recrystallization within annealling of CC 5083 and CC 5182 aluminum alloy is 371 ℃. The grain grow up outstanding of cold rooled CC 5152 aluminum alloy after annealed with 454 ℃ in the electric furnace and salt bath furnace. The start temperature of grain grow up of CC 5083 alluminum alloy annealed in the electric furnace and salt bath furnace respectively is higher than the start temperature of grain grow up of CC 5182 alluminum alloy annealed in the electric furnace and salt bath furnace respectively. The strat temperature of recrystallization grain grow up is higher than which annealled with other three manner annealing process. The recrystallization temperature of CC 5182 annealed in the salt bath furnace is higher than which annealed in the electric furnace. The recrystallization temperature of the surface layer of CC 5083 and CC 5182 aluminum alloy is higher than the inner layer (the innovation point). There is a difference each other of the structure and the texture of the four manner annealing aluminum alloy (the innovation point). There is a little difference at the recrystallization processes course reflectived by the observe results of structure transform and by the examination results of texture transmission..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 814 (2015)
The Prediction Algorithm of the Optimal X-Ray Tube Voltage in Variable Energy Imaging
BI Yan, CHEN Ping, and HAN Yan
X-ray variable energy imaging can obtain the sectional information of complicated structural component successively, and get the whole information by multi-spectrum fusion. Now the energy parameters of X ray imaging mainly depend on man-made setting with the certain step voltage. However this modulation doesn’t match tX-ray variable energy imaging can obtain the sectional information of complicated structural component successively, and get the whole information by multi-spectrum fusion. Now the energy parameters of X ray imaging mainly depend on man-made setting with the certain step voltage. However this modulation doesn’t match to the attenuation thickness variation of the object. Therefore, this paper proposes an optimum tube voltage prediction algorithm based on variable energy imaging. It extracts the effective thickness (ET) and near the effective thickness (NET) in the image sequences which are acquired by pre-scanning the detected object. Then it establishes a physical model between image gray, tube voltage and X ray spectrum. And the model of voltage and gray difference between the ET (high quality area) and NET (prediction area) is also established. On the basis of these two models, the optimal imaging energy forecasting model of NET is modeled. Then, solve the model and get the optimal voltage for NET. At last, by the experiment of the steel blocks with different thickness, testify this prediction algorithm. The results compared with the actual values showed that the prediction algorithm can accurately predict 3 or 4 mm at low voltage and 7 or 10 mm at high voltage. Prediction accuracy is over 95%..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 820 (2015)
Object Separation from Medical X-Ray Images Based on ICA
LI Yan, YU Chun-yu, MIAO Ya-jian, FEI Bin, and ZHUANG Feng-yun
X-ray medical image can examine diseased tissue of patients and has important reference value for medical diagnosis. With the problems that traditional X-ray images have noise, poor level sense and blocked aliasing organs, this paper proposes a method for the introduction of multi-spectrum X-ray imaging and independentX-ray medical image can examine diseased tissue of patients and has important reference value for medical diagnosis. With the problems that traditional X-ray images have noise, poor level sense and blocked aliasing organs, this paper proposes a method for the introduction of multi-spectrum X-ray imaging and independent component analysis (ICA) algorithm to separate the target object. Firstly image de-noising preprocessing ensures the accuracy of target extraction based on independent component analysis and sparse code shrinkage. Then according to the main proportion of organ in the images, aliasing thickness matrix of each pixel was isolated. Finally independent component analysis obtains convergence matrix to reconstruct the target object with blind separation theory. In the ICA algorithm, it found that when the number is more than 40, the target objects separate successfully with the aid of subjective evaluation standard. And when the amplitudes of the scale are in the［25, 45］ interval, the target images have high contrast and less distortion. The three-dimensional figure of Peak signal to noise ratio (PSNR) shows that the. different convergence times and amplitudes have a greater influence on image quality. The contrast and edge information of experimental images achieve better effects with the convergence times 85 and amplitudes 35 in the ICA algorithm..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 825 (2015)
Contrast of Z-Pinch X-Ray Yield Measure Technique
LI Mo, WANG Liang-ping, SHENG Liang, and LU Yi
Resistive bolometer and scintillant detection system are two mainly Z-pinch X-ray yield measure techniques which are based on different diagnostic principles. Contrasting the results from two methods can help with increasing precision of X-ray yield measurement. Experiments with different load material and shape were cResistive bolometer and scintillant detection system are two mainly Z-pinch X-ray yield measure techniques which are based on different diagnostic principles. Contrasting the results from two methods can help with increasing precision of X-ray yield measurement. Experiments with different load material and shape were carried out on the “QiangGuang-I” facility. For Al wire arrays, X-ray yields measured by the two techniques were largely consistent. However, for insulating coating W wire arrays, X-ray yields taken from bolometer changed with load parameters while data from scintillant detection system hardly changed. Simulation and analysis draw conclusions as follows: (1) Scintillant detection system is much more sensitive to X-ray photons with low energy and its spectral response is wider than the resistive bolometer. Thus, results from the former method are always larger than the latter. (2) The responses of the two systems are both flat to Al plasma radiation. Thus, their results are consistent for Al wire array loads. (3) Radiation form planar W wire arrays is mainly composed of sub-keV soft X-ray. X-ray yields measured by the bolometer is supposed to be accurate because of the nickel foil can absorb almost all the soft X-ray. (4) By contrast, using planar W wire arrays, data from scintillant detection system hardly change with load parameters. A possible explanation is that while the distance between wires increases, plasma temperature at stagnation reduces and spectra moves toward the soft X-ray region. Scintillator is much more sensitive to the soft X-ray below 200 eV. Thus, although the total X-ray yield reduces with large diameter load, signal from the scintillant detection system is almost the same. (5) Both Techniques affected by electron beams produced by the loads..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 829 (2015)
Searching for Rare Celestial Objects Automatically from Stellar Spectra of the Sloan Digital Sky Survey Data Release Eight
SI Jian-min, LUO A-li, WU Fu-zhao, and WU Yi-hong
There are many valuable rare and unusual objects in spectra dataset of Sloan Digital Sky Survey (SDSS) Data Release eight (DR8), such as special white dwarfs (DZ, DQ, DC), carbon stars, white dwarf main-sequence binaries (WDMS), cataclysmic variable (CV) stars and so on, so it is extremely significant to search for rarThere are many valuable rare and unusual objects in spectra dataset of Sloan Digital Sky Survey (SDSS) Data Release eight (DR8), such as special white dwarfs (DZ, DQ, DC), carbon stars, white dwarf main-sequence binaries (WDMS), cataclysmic variable (CV) stars and so on, so it is extremely significant to search for rare and unusual celestial objects from massive spectra dataset. A novel algorithm based on Kernel dense estimation and K-nearest neighborhoods (KNN) has been presented, and applied to search for rare and unusual celestial objects from 546 383 stellar spectra of SDSS DR8. Their densities are estimated using Gaussian kernel density estimation, the top 5 000 spectra in descend order by their densities are selected as rare objects, and the top 300 000 spectra in ascend order by their densities are selected as normal objects. Then, KNN were used to classify the rest objects, and simultaneously K nearest neighbors of the 5 000 rare spectra are also selected as rare objects. As a result, there are totally 21 193 spectra selected as initial rare spectra, which include error spectra caused by deletion, redden, bad calibration, spectra consisting of different physically irrelevant components, planetary nebulas, QSOs, special white dwarfs (DZ, DQ, DC), carbon stars, white dwarf main-sequence binaries (WDMS), cataclysmic variable (CV) stars and so on. By cross identification with SIMBAD, NED, ADS and major literature, it is found that three DZ white dwarfs, one WDMS, two CVs with company of G-type star, three CVs candidates, six DC white dwarfs, one DC white dwarf candidate and one BL Lacertae (BL lac) candidate are our new findings. We also have found one special DA white dwarf with emission lines of CaⅡ triple and MgⅠ, and one unknown object whose spectrum looks like a late M star with emission lines and its image looks like a galaxy or nebula..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 834 (2015)
Optical Design of Miniature Infrared Gratings Spectrometer Based on Planar Waveguide
LI Yang-yu, FANG Yong-hua, LI Da-cheng, and LIU Yang
In order to miniaturize an infrared spectrometer, we analyze the current optical design of miniature spectrometers and propose a method for designing a miniature infrared gratings spectrometer based on planar waveguide. Common miniature spectrometer uses miniature optical elements to reduce the size of system, which alIn order to miniaturize an infrared spectrometer, we analyze the current optical design of miniature spectrometers and propose a method for designing a miniature infrared gratings spectrometer based on planar waveguide. Common miniature spectrometer uses miniature optical elements to reduce the size of system, which also shrinks the effective aperture. So the performance of spectrometer has dropped. Miniaturization principle of planar waveguide spectrometer is different from the principle of common miniature spectrometer. In planar waveguide spectrometer, the propagation of light is limited in a thin planar waveguide, which looks like the whole optical system is squashed flat. In the direction parallel to the planar waveguide, the light through the slit is collimated, dispersed and focused. And a spectral image is formed in the detector plane. This propagation of light is similar to the light in common miniature spectrometer. In the direction perpendicular to the planar waveguide, light is multiple reflected by the upper and lower surfaces of the planar waveguide and propagates in the waveguide. So the size of corresponding optical element could be very small in the vertical direction, which can reduce the size of the optical system. And the performance of the spectrometer is still good. The design method of the planar waveguide spectrometer can be separated into two parts, Czerny-Turner structure design and planar waveguide structure design. First, by using aberration theory an aberration-corrected (spherical aberration, coma, focal curve) Czerny-Turner structure is obtained. The operation wavelength range and spectral resolution are also fixed. Then, by using geometrical optics theory a planar waveguide structure is designed for reducing the system size and correcting the astigmatism. The planar waveguide structure includes a planar waveguide and two cylindrical lenses. Finally, they are modeled together in optical design software and are optimized as a whole. An infrared planar waveguide spectrometer is designed using this method. The operation wavelength range is 8~12 μm, the numerical aperture is 0.22, and the linear array detector contains 64 elements. By using Zemax software, the design is optimized and analyzed. The results indicate that the size of the optical system is 130 mm×125 mm×20 mm and the spectral resolution of spectrometer is 80 nm, which satisfy the requirements of design index. Thus it is this method that can be used for designing a miniature spectrometer without movable parts and sizes in the range of several cubic centimeters..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 841 (2015)
Portable High-Precision System for CH4 Concentration Detection in Mines based on the Laser Mode-Hopping
LU Xu-tao, LI Jing, and LV Hai-feng
In order to detect rapid, portable concentration of methane in the mine, meanwhile, the system includeed a high sensitivity and a long working period, designed differential optical absorption spectroscopy method based on mode-hopping of semiconductor laser, and established wireless detection system for concentration ofIn order to detect rapid, portable concentration of methane in the mine, meanwhile, the system includeed a high sensitivity and a long working period, designed differential optical absorption spectroscopy method based on mode-hopping of semiconductor laser, and established wireless detection system for concentration of methane in the mine. Output wavelengths of the semiconductor laser occurred mode-hopping by modulation current of the system, so it obtained the two wavelengths close to the laser, and one is on the characteristic absorption peak of methane, while the other is not substantially absorbed. When the two beams of light were illuminated test chamber, methane concentration of the gas chamber was solved by Bill Lambert law with the difference of the light intensity between the two beams. Light source used DFB single mode semiconductor laser from Japan Anritsu company. Experimental results show that, when the modulation current increased from 20.0 to 60.0 mA, output wavelength occurred mode-hopping when the modulation current reached 48.3 mA, and output wavelength changed to 1 651.020 nm from 1 650.888 nm. By HITRAN spectrum database, it showed that the position of the wavelength 1 650.888 nm can be used for characteristic absorption peaks, while the wavelength 1 651.020 nm was suitable for reference wavelength. On this basis, the standard concentrations of methane gas was tested in the sealed container, test data of the system was compared to the H-BD5GD410-HC portable methane detector. Test results of the system and the H-BD5GD410-HC portable methane detector were similar, but with the constant concentration increased, the detection error of the system is relatively stable, slightly better than the portable methane detector. Detection error of system were less than 0.050%, under the conditions that there were without the use of expensive phase lock or inspection phase circuit, to achieve the accuracy of better than 0.10% concentration of methane detected in the mine..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 846 (2015)
An Effective Wavelength Detection Method Based on Echelle Spectra Reduction
YIN Lu, Bayanheshig, CUI Ji-cheng, YANG Jin, ZHU Ji-wei, and YAO Xue-feng
Echelle spectrometer with high dispersion, high resolution, wide spectral coverage, full spectrum transient direct-reading and many other advantages, is one of the representative of the advanced spectrometer. In the commercialization trend of echelle spectrometer, the method of two-dimension spectra image processing isEchelle spectrometer with high dispersion, high resolution, wide spectral coverage, full spectrum transient direct-reading and many other advantages, is one of the representative of the advanced spectrometer. In the commercialization trend of echelle spectrometer, the method of two-dimension spectra image processing is becoming more and more important. Currently, centroid extraction algorithm often be used first to detect the centroid position of effective facula and then combined with echelle spectrum reduction method to detect the effective wavelength, but this method is more difficult to achieve the desired requirements. To improve the speed, accuracy and the ability of imaging error correction during detecting the effective wavelength, an effective wavelength detection method based on spectra reduction is coming up. At the beginning, the two-dimension spectra will be converted to a one-dimension image using echelle spectra reduction method instead of finding centroid of effective facula. And then by setting appropriate threshold the one-dimension image is easy to be dealing with than the two-dimension spectra image and all of the pixel points stand for effective wavelength can be detected at one time. Based on this new idea, the speed and accuracy of image processing have been improved, at the same time a range of imaging errors can be compensated. Using the echelle spectrograph make a test applying this algorithm for data processing to check whether this method is fit for the spectra image processing or not. Choosing a standard mercury lamp as a light source during the test because the standard mercury lamp have a number of known characteristic lines which can be used to examine the accuracy of wavelength detection. According to experimental result, this method not only increase operation speed but improve accuracy of wavelength detection, also the imaging error lower than 0.05 mm (two pixel) can be corrected, and the wavelength accuracy would up to 0.02 nm which can satisfy the requirements of echelle spectrograph for image processing..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 850 (2015)
In-Flight Radiometric Calibration for ZY-3 Satellite Multispectral Sensor by Modified Reflectance-Based Method
HAN Jie, XIE Yong, GU Xing-fa, YU Tao, LIU Qi-yue, and GAO Rong-jun
Through integrating multi-spectral sensor characteristics of ZY-3 satellite, a modified reflectance-based method is proposed and used to achieve ZY-3 satellite multispectral sensor in-flight radiometric calibration. This method chooses level 1A image as data source and establishes geometric model to get an accurate obsThrough integrating multi-spectral sensor characteristics of ZY-3 satellite, a modified reflectance-based method is proposed and used to achieve ZY-3 satellite multispectral sensor in-flight radiometric calibration. This method chooses level 1A image as data source and establishes geometric model to get an accurate observation geometric parameters at calibration site according to the information provided in image auxiliary documentation, which can reduce the influences on the calibration accuracy from image resampling and observation geometry errors. We use two-point and multi-points methods to calculate the absolute radiometric calibration coefficients of ZY-3 satellite multispectral sensor based on the large campaign at Dongying city, Shan Dong province. Compared with ZY-3 official calibration coefficients, multi-points method has higher accuracy than two-point method. Through analyzing the dispersion between each calibration point and the fitting line, we find that the residual error of water calibration site is larger than others, which of green band is approximately 67.39%. Treating water calibration site as an error, we filter it out using 95.4% confidence level as standard and recalculate the calibration coefficients with multi-points method. The final calibration coefficients show that the relative differences of the first three bands are less than 2% and the last band is less than 5%, which manifests that the proposed radiometric calibration method can obtain accurate and reliable calibration coefficients and is useful for other similar satellites in future..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 856 (2015)
[in Chinese]
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 35, Issue 3, 1 (2015)
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