Journals >Spectroscopy and Spectral Analysis
Contents
2014
Volume: 34 Issue 2
57 Article(s)
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Research Article
A Comparative Analysis of the Passive Electric Probe Detection and Spectrum Diagnosis of Laser-Induced Plasma
LIU Tong, YANG Li-jun, WANG Li-jun, and WANG Lang-ping
An approach to detecting laser-induced plasma using passive probe was brought up. The plasma of laser welding was studied by using a synchronous electric and spectral information acquisition system, the laser-induced plasma was detected by a passive electric probe and fiber spectrometer, the electrical signal was analyAn approach to detecting laser-induced plasma using passive probe was brought up. The plasma of laser welding was studied by using a synchronous electric and spectral information acquisition system, the laser-induced plasma was detected by a passive electric probe and fiber spectrometer, the electrical signal was analyzed on the basis of the theory of plasma sheath, and the temperature of laser-induced plasma was calculated by using the method of relative spectral intensity. The analysis results from electrical signal and spectral one were compared. Calculation results of three kinds of surface circumstances, which were respectively coated by KF, TiO2 and without coating, were compared. The factors affecting the detection accuracy were studied. The results indicated that the results calculated by passive probe matched that by spectral signal basically, and the accuracy was affected by ions mass of the plasma. The designed passive electric probe can be used to reflect the continuous fluctuation of electron temperature of the generated plasma, and monitor the laser-induced plasma..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 289 (2014)
A Spectral Scanning Filtering Method for Improving the SNR of Chirped Pulse Based on the Photorefractive Effect
YE Rong, ZHANG Bin, ZENG Bing, SUN Nian-chun, SUI Zhan, and MA Zai-ru
Based on the principle of spectral scanning filtering method, a new scanning filtering method for improving signal-to-noise ratio (SNR) of the chirped pulse by using the photorefractive effect was proposed and theoretically analyzed. For the scanning filtering implement of Fabry-Perot (F-P) etalon with a built-in photoBased on the principle of spectral scanning filtering method, a new scanning filtering method for improving signal-to-noise ratio (SNR) of the chirped pulse by using the photorefractive effect was proposed and theoretically analyzed. For the scanning filtering implement of Fabry-Perot (F-P) etalon with a built-in photorefractive crystal, the transmittance spectral characteristics of the scanning filter were analyzed quantitatively. Furthermore, the effects of the reflectivity of the parallel-plates of Fabry-Perot etalon, the bandwidth of the transmittance spectral window, the variation of the controlling parameters of the applied field and the variation of the chirped rate to the photorefractive crystal on the SNR improvement and the overall transmittance were discussed in details. The results show that the higher the reflectivity of the F-P parallel-plates is, the transmittance spectral is sharper and the transmittance window is narrower, resulting in the better filtering effect. In order to ensure the efficient SNR improvement, the reflectivity of the F-P parallel-plates should be higher than 0.99. The control of the applied field exhibits significant impact on the scanning filtering. In practical applications, the applied field and chirped rate should be controlled precisely in order to ensure the synchronous matching between the signal pulse and the filtering function. For the chirped signal pulse with the central wavelength 800 nm, the SNR improvement of about 3 orders of magnitude can be obtained via filtering out the amplified spontaneous emission (ASE) random noise and pre-pulse by the use of the spectral scanning filtering method proposed in this paper..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 293 (2014)
Variations in Toxic Metal Levels of Two Fish Species, Pomatomus saltatrix and Dicentrarchus labrax, and Risk Estimation for Children
Mehmet Yaman, and Ibrahim H Yaman
The concentrations of five toxic metals were monthly determined in two fish species, obtained from fish markets in Turkey during 2010—2011. For the determinations, AAS and ICP-AES were used. The obtained lead concentrations for all studied Pomatomus saltatrix (mean 635 μg·kg-1) and Dicentrarchus labrax (mean 463 μThe concentrations of five toxic metals were monthly determined in two fish species, obtained from fish markets in Turkey during 2010—2011. For the determinations, AAS and ICP-AES were used. The obtained lead concentrations for all studied Pomatomus saltatrix (mean 635 μg·kg-1) and Dicentrarchus labrax (mean 463 μg·kg-1) samples were found to be significantly higher than the maximum allowances concentration (MAC) of 300 μg·kg-1. Mean chromium (324 μg·kg-1) and Cu (940 μg·kg-1) concentrations in Pomatomus saltatrix were higher than in Dicentrarchus labrax (268 μg Cr·kg-1 and 600 μg Cu·kg-1) while Ni in Pomatomus saltatrix (216 μg·kg-1) was lower in Dicentrarchus labrax (291 μg·kg-1). The estimated non-carcinogenic and carcinogenic health risks by the Target Hazard Quotient and target carcinogenic risk indicate that there are no sytemic effects, and the risk of developing cancer over a human lifetime is between 2～9 in 1 000 000..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 300 (2014)
Study on Spectral Line Profile of Volume Discharge and Surface Discharge in Dielectric Barrier Discharge
DONG Li-fang, ZHAO Long-hu, WANG Yong-jie, and GAO Ye-nan
The volume discharge (VD) and surface discharge (SD) were observed in dielectric barrier discharge with a relatively large discharge gap simultaneously by using a high-speed camera. The variations of the spectral line profiles of VD and SD as a function of the discharge parameters were studied by using optical emissionThe volume discharge (VD) and surface discharge (SD) were observed in dielectric barrier discharge with a relatively large discharge gap simultaneously by using a high-speed camera. The variations of the spectral line profiles of VD and SD as a function of the discharge parameters were studied by using optical emission spectra. The changes in the width and shift of Ar Ⅰ（2P2→1S5）spectral lines of VD and SD with gas pressure and discharge gap were measured in dielectric barrier discharge in argon. It was found that both the width and shift of SD are bigger than those of VD, indicating that the electron density of SD is higher than that of VD. The width and shift of VD and SD increase with the gas pressure increasing, indicating that the electron density of VD and SD increases with the gas pressure increasing. The width of VD and SD increases with the gas gap d increasing from 3.8 to 4.4 mm, reflecting that the electron density of VD and SD increases with d increasing..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 308 (2014)
The Influence of Temperature on the Orientation of Pigments in PSⅡ
LU Li-ping, WEI Liang-shu, LUO Xiao-sen, NI Xiao-wu, and LU Jian
The effect of temperature on the orientation of pigment in PSⅡwas studied by the fluorescence excitation spectra and polarization fluorescence spectra of spinach thylakoid solution. The experimental results showed that in the temperature range of 15～45 ℃ the absorption band of chl a at 436 nm at room temperature red-shThe effect of temperature on the orientation of pigment in PSⅡwas studied by the fluorescence excitation spectra and polarization fluorescence spectra of spinach thylakoid solution. The experimental results showed that in the temperature range of 15～45 ℃ the absorption band of chl a at 436 nm at room temperature red-shifted with increasing temperature. The excitation spectra intensity reached the maximum at the temperature of 35 ℃, but greatly reduced with temperature at 65 and 78 ℃. In the polarization fluorescence spectra the fluorescence peak of PSⅡ didn’t change with temperature from 15 to 45 ℃. It was also found that the calculated fluorescence polarization degree increased with the temperature in the entire temperature range. The analysis indicated that temperature would affect the orientation of the pigments in PSII and the coupling strength between pigments so to change photosynthetic efficiency. The results will give a certain reference for the study of the energy absorption and transmission, regulation mechanism and also on solar cell materials..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 312 (2014)
Study on the Safety of Blue Light Leak of LED
SHEN Chong-yu, XU Zheng, ZHAO Su-ling, and HUANG Qing-yu
In this paper, the blue light properties of LED illumination devices have been investigated. Against the status quo of China’s LED lighting, we measured the spectrum component of LED lamps and analyzed the photobiological safety under the current domestic and international standards GB/T 20145-2006/CIE S009/E: 2002 andIn this paper, the blue light properties of LED illumination devices have been investigated. Against the status quo of China’s LED lighting, we measured the spectrum component of LED lamps and analyzed the photobiological safety under the current domestic and international standards GB/T 20145-2006/CIE S009/E: 2002 and IEC62471: 2006 standards as well as CTL-0744_2009-laser resolution, which provides the reference to the manufacture of LED lighting lamps as well as related safety standards and laws. If the radiance intensity of blue light in LED is lower than 100 W·m-2·Sr-1, there is no harm to human eyes. LEDs will not cause harm to human eyes under normal use, but we should pay attention to the protection of special populations (children), and make sure that they avoid looking at a light source for a long time. The research has found that the blue-rich lamps can affect the human rule of work and rest, and therefore, the LED lamps with color temperature below 4 000 K and color rendering index of 80 are suitable for indoor use. At the same time, the lamps with different parameters should be selected according to the different distances..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 316 (2014)
Effect of Spacer on Red and Green Phosphorescent Organic Light-Emitting Devices
ZHANG Wei, ZHANG Fang-hui, and HUANG Jin
We have investigated the performances of organic light-emitting diodes (OLED) with different spacer, the structure was fabricated as ITO/MoO3（40 nm）/NPB(40 nm)/TCTA(10 nm)/CBP∶GIr114%∶R-4B2%(30 nm)/spacer (3 nm)/ CBP∶GIr114%∶R-4B2%(30 nm)/BCP(10 nm)/Alq3(40 nm)/LiF(1 nm)/Al(100 nm), the spacers were CBP， TCTA， TPBI andWe have investigated the performances of organic light-emitting diodes (OLED) with different spacer, the structure was fabricated as ITO/MoO3（40 nm）/NPB(40 nm)/TCTA(10 nm)/CBP∶GIr114%∶R-4B2%(30 nm)/spacer (3 nm)/ CBP∶GIr114%∶R-4B2%(30 nm)/BCP(10 nm)/Alq3(40 nm)/LiF(1 nm)/Al(100 nm), the spacers were CBP， TCTA， TPBI and BCP separately, GIr1 and R-4B were green and red phosphorescent dye respectively. The results showed that compared to the reference device utilized CBP as the spacer layer, TCTA， TPBI and BCP had higher current efficiency in excess of 59%， 79% and 93%, the maximum current efficiency of 16.91 cd·A－1 was achieved with BCP as the spacer at voltage of 5 V, TPBI and BCP as the spacer layer obtained the higher current density and lower efficiency roll-off. We attributed to these results to the follow reasons, the first was that carriers and excitons were limited to a narrow recombination region because of TCTA with higher LUMO energy level and triplet energy, which improved the probability of carriers recombination, in addition, more serious quenching at higher current density. The second reason was that TPBI and BCP had the higher HOMO energy level and electron mobility, which broadened excitons recombination zone. In addition, the spacer layer caused the accumulation of electrons or holes and the formation of high space electric field, leading to carrier injection and transport more effectively. In particular, we obtained a better stability of phosphorescent organic light-emitting diodes since the way for the red and green co-doped with host material..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 322 (2014)
The Electroluminescence Spectra of InGaN/GaN Blue LEDs During Aging Time
DAI Shuang, YU Tong-jun, LI Xing-bin, YUAN Gang-cheng, and LU Hui-min
The luminescence spectra of InGaN/GaN multiple quantum wells light-emitting diodes under low level injection current (<4 mA) during aging process was investigated for the first time. Comparing the electroluminescence (EL) spectra of LEDs before and after aging time it was found that the peak wavelength and the full The luminescence spectra of InGaN/GaN multiple quantum wells light-emitting diodes under low level injection current (<4 mA) during aging process was investigated for the first time. Comparing the electroluminescence (EL) spectra of LEDs before and after aging time it was found that the peak wavelength and the full width at half maximum (FWHM) decreased with stress time and the changes of EL spectrum had two different stages-drastic decrease at the early stress stage and slow decrease later showing the same trend with the output optical power of LEDs, which indicates that the effective polarization electric field of LEDs becomes weak during the aging process and the change has a clear correlation with the increase of the defects in the multiple quantum wells of LEDs. Electrical measurement revealed that junction capacitance (Cj) under the same junction voltage (Vj=1.8 V) and the junction voltage (Vj) with the same injection current 1 mA calculated by ac small-signal IV method increased along with aging time, which explicates that the carrier density under the same low injection increases as the aging time increases. Analyses indicate that the polarization field in the quantum well is more seriously screened by the increased carriers captured by defects activated during stress time, the weaker effective polarization electric field makes the tilt of the energy band smaller, the energy radiated through the band edge and the density of energy states of the band edge increase which leads to the behaviors of peak wavelength and the FWHM of InGaN/GaN multiple quantum wells LEDs under low level injection current..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 327 (2014)
Silicon Nanocrystals Doping and Surface Modification
ZHANG Nian-bo, TIAN Jin-xiu, LI Wei, WU Li-li, LI Bing, ZHANG Jing-quan, FENG Liang-huan, and XU Ming
Using the first-principles method based on density functional theory, at the generalized gradient approximation (GGA), the state density, the change of binding energy and the energy gap of the silicon nanocrystals (Si75H76) with the circumstances of boron (B)-doped , phosphorus (P)-doped and the surface modification wiUsing the first-principles method based on density functional theory, at the generalized gradient approximation (GGA), the state density, the change of binding energy and the energy gap of the silicon nanocrystals (Si75H76) with the circumstances of boron (B)-doped , phosphorus (P)-doped and the surface modification with ethyl (CH2CH3), isopropyl (—CH(CH3)2) have been calculated. The results showed that the B or P-doped have little impact on the energy gap value (3.12 eV) of silicon nanocrystals (SiNcs), except that some energy levels will be introduced in the forbidden band. The energy level caused by three-coordinated B-doped SiNcs is Ec-0.8 eV, while it is Ev+0.2 eV for the three-coordinated P-doped. However, the energy level position is Ev+0.4 eV for the four-coordinated B-doped SiNcs, and Ec-1.1 eV for the four-coordinated P-doped. Total energy of the system with the four-coordinated doped is lower than that with the three-coordinated doped in the other same conditions. The total energy of SiNcs system lessen when the surface is modified with appropriate ethyl or isopropyl. The total energy decreases with the surface coverage of organo-functional group increasing. But, the calculation can’t converge because of too high resistance when the SiNcs surface are grafted with too many organic groups..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 331 (2014)
Technique Progress of High-Precision Gas Absorption Spectroscopy with Femtosecond Optical Frequency Comb
YANG Hong-lei, WEI Hao-yun, LI Yan, REN Li-bing, and ZHANG Hong-yuan
Femtosecond optical frequency comb, with large spectral range, narrow pulse width, high stability of frequency and many other remarkable properties, has a significant impact on optical frequency metrology, absolute distance measurement and high-precision spectroscopy. The time-domain and frequency-domain properties of Femtosecond optical frequency comb, with large spectral range, narrow pulse width, high stability of frequency and many other remarkable properties, has a significant impact on optical frequency metrology, absolute distance measurement and high-precision spectroscopy. The time-domain and frequency-domain properties of femtosecond optical frequency comb is traced back to the microwave frequency standard, making it possible to open up the door to high-precision gas absorption spectrum detection. Femtosecond optical frequency comb spectroscopy has some excellent performances, such as fast measurement, high sensitivity, high resolution, high signal-to-noise ratio and so on. Therefore, more investments on femtosecond optical frequency comb spectroscopy will better make contribution to the environmental protection, industrial production, biological medicine, scientific research and other social fields. High-precision gas absorption spectroscopy with femtosecond optical frequency comb mainly includes frequency comb based cavity ring-down spectroscopy, cavity-enhanced frequency comb spectroscopy and dual-comb multi-heterodyne spectroscopy. Among them, according to the data collection, cavity-enhanced frequency comb spectroscopy can be divided into comb vernier method, virtually imaged phased array method and Fourier transform method. At present, related research has been widely carried out abroad, and domestic research is still in its infancy. This review summarizes main techniques in the high-precision gas absorption spectrum detection based on optical frequency comb, and demonstrates typical experimental schemes for different methods. It also analyzes the advantages and disadvantages of each method, and tracks frontier achievements of main research groups..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 335 (2014)
Applications and Progress of Fourier Transform Infrared Spectroscopic Microimaging in Bone Disease Research
YIN Jian-hua, HUANG Feng-ling, QIAN Zhi-yu, and XIE Jie-ru
Fourier transform infrared spectroscopy (FTIRS) and microimaging technique have been integrated together to evolve into Fourier transform infrared spectroscopic imaging (FTIRI) system. This system can provide not only the morphological information of the sample by visible image and FTIR image, but also the abundant infFourier transform infrared spectroscopy (FTIRS) and microimaging technique have been integrated together to evolve into Fourier transform infrared spectroscopic imaging (FTIRI) system. This system can provide not only the morphological information of the sample by visible image and FTIR image, but also the abundant information on the spectral, component and structure of specimen by FTIRS, especially of the heterogeneous solid mixture. The richer and more visualized information obtained by FTIRI greatly raised the research efficiency and usability of the spectral technique in biomedicine, pharmacology, forensic medicine, material science and chemistry, etc. The present paper depicts FTIRI development process, system structure, imaging principle and mode selection; and then introduces that FTIRI opened a new area of investigation for biomedicine, namely, research on bone disease by FTIRI. Then the paper illustrates the related research findings and progress in FTIRI use for osteopetrosis, osteogenesis imperfecta, osteoporosis and osteomalacia, as well as a couple of limitations. The prospective study for FTIRI in biomedical research field is also addressed..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 340 (2014)
Analysis of Leave FTIR of Nine Kinds of Plants from Rosaceae with Genetic Relationship
QIU Lu, LI Xiao-yong, LIU Peng, FAN Shu-guo, XIE Mei-hua, LIU Ren-ming, ZHOU Lin-zong, and WANG Jing
Leaves of nine kinds of plants from three subfamily of Rosaceae were used as materials. Genetic relationship was analyzed and species were identified through studying FTIR of nine kinds of plants. Leaves mainly contain large amounts of carbohydrates, proteins, lipids, nucleic acids and other substances. The peaks of caLeaves of nine kinds of plants from three subfamily of Rosaceae were used as materials. Genetic relationship was analyzed and species were identified through studying FTIR of nine kinds of plants. Leaves mainly contain large amounts of carbohydrates, proteins, lipids, nucleic acids and other substances. The peaks of carbohydrates are mainly between 1 440 and 775 cm-1. The vibration peaks of the cellulose and lignin are between 1 440 and 1 337 cm-1. The peaks between 1 000 and 775 cm-1 are stretching vibration of ribose. The vibration peaks of protein are between 1 620 and 1 235 cm-1. The peak at 1 620 cm-1 is sensitive to CO stretching vibration of protein amide Ⅰ. The peak at 1 523 cm-1 is assigned to N—H and C—N stretching vibration of protein amide Ⅱ. Peaks of lipids mainly appeared between 2 930 and 1 380 cm-1. The peak at 2 922 cm-1 is CH2 stretching vibration of fat. The peak at 1 732 cm-1 is CO stretching vibration of fatty acids. The mark peak of the nucleic acid appears in the region between 1 250 and 1 000 cm-1. The peak at 1 068 cm-1 is due to the symmetric stretching vibration of PO2－ group of the phosphodiester-deoxyribose backbone, and the peak at 1 246 cm-1 is associated to the asymmetric stretch vibration of PO2－ group. The results showed that the cluster model is established by smoothing, standardizing, the second derivative, principal component analysis and Hierarchical cluster analysis. It is accordant with the traditional classification. The result of cluster shows that Prunus armeniaca L. and Prunus seudocerasus Lindl. were clustered into one (Prunoideae). Potentilla fulgens Wall. Rosa chinensis Jacd and Fragaria ananassa Duchesne var. were clustered into the second (Rosoideae). Pyracantha fortuneana Li, Malus pumila Mill. Eriobotrya bengalensis Hook.f.and Malus hallianna Koehne were clustered into the third (Pomoideae). The correct rate of cluster at subfamily is 100%. The correct rate of cluster at genus is 55.56%. The correct rate of identification is 100% when unknown species waiting for determined were laid into the model of Hierarchical cluster to identify. This study provides a new thought and method for genetic relationship analysis of planst..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 344 (2014)
Study on Predicting Total Acid Content and Soluble Sugar of Tomato Juice by Near Infrared Optical Fiber Spectrometer Technique
ZHANG Bing-fang, YUAN Li-bo, and ZHANG Bing-xiu
In order to explore a simple, rapid and efficient tomato quality detection method, in the present experiment near infrared spectroscopy and optical fiber sensing technology were applied to quickly measure the nutrition ingredient content in tomato juice samples. The main instrument used in this experiment was near infrIn order to explore a simple, rapid and efficient tomato quality detection method, in the present experiment near infrared spectroscopy and optical fiber sensing technology were applied to quickly measure the nutrition ingredient content in tomato juice samples. The main instrument used in this experiment was near infrared optical fiber spectrometer in a wavelength range from 900 to 2 500 nm, which measured the absorbance of the tomato juice samples; A collection of one hundred and sixty-four tomato juice samples were selected as the standard samples, the spectra and the corresponding chemical value were measured. Partial least squares (PLS) was adopted to establish the mathematical model of the total acid and soluble sugar content in tomato juice samples, and the regression equation was statistically analysed. The total acid in tomato juice prediction correlation coefficient was 0.967, calibration standard deviation (RMSEC) was 0.133, standard error of prediction (RMSEP) was 0.103; the soluble sugar prediction correlation coefficient is 0.976, calibration standard deviation (RMSEC) was 0.463, and the standard error of prediction (RMSEP) was 0.460. The above data achieved better forecasting results, which showed that the method of quantitative analysis of tomato fruit multicomponent content was feasible. The method is rapid, simple and can do multicomponent analysis on the same sample simultaneously. It is a promising sensor and gradually becoming a international research focus in sensor field..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 350 (2014)
IFTIR Study on the Micro-Structure in the Construction Process of Water-Borne Coatings
CHEN Hang, LUO Wen, GUAN Xue-song, LI Hong-jian, TAN Rui, and YIN Wen-xuan
borne paint was studied in the article in which the solvent water was regarded as a variable factor. A series of paint samples with different percentage of water were configured before observing their storage performance and microstructures by using Fourier-transform infrared (FTIR) ATR (attenuated total reflection) spborne paint was studied in the article in which the solvent water was regarded as a variable factor. A series of paint samples with different percentage of water were configured before observing their storage performance and microstructures by using Fourier-transform infrared (FTIR) ATR (attenuated total reflection) spectroscopy and diffuse reflectance (DF) FTIR spectroscopy. The effects of construction process and solvent water on the coating film were examined through analyzing the changes of internal functional groups before and after coating. The results indicated that as the amount of solvent water was increased, the characteristic peak of νCO in 1 727 cm-1 turned into acromion, the absorption peak in 871 cm-1 was blue shifted, the intensity of the peak of hydroxyl (νOH) in 3 400 cm-1 and unsaturated absorption peak of ν—CH in 3 030 cm-1 gradually weakened, the absorption peaks strengths of ν—CH3 and ν—CH2 in 2 962 and 2 871 cm-1 increased, respectively. The absorption peak in 2 516 cm-1 was shifted to 2 603 cm-1 then form the acromion, the absorption peak of 1 647 cm-1 gradually changed to 1 455 cm-1, the stretching vibration absorption peak of νC—O in 1 107 cm-1 was red-shifted. During the coating process of paint, the solvent water and paint molecules interacted with each other, having a significant impact on the electron cloud density distribution of the paint molecules. The results obtained in the article have an important significance for the production and construction of paint..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 354 (2014)
Spectral Characterization for Capsanthin Molecule with in Vitro Oxidative Defense Reaction
ZHENG Wen-yu, DING Zhu-hong, and LIU Hai
The changes of UV-Vis and FTIR spectroscopic properties for capsanthin before and after reaction with exogenous superoxide anion(·O-2), hydrogen peroxide(H2O2) and hydroxyl radical(·OH), catalase(CAT), peroxidase(POD) and lipoxygenase(LOX) were explored. The results showed that, the UV-Vis spectral absorptionThe changes of UV-Vis and FTIR spectroscopic properties for capsanthin before and after reaction with exogenous superoxide anion(·O-2), hydrogen peroxide(H2O2) and hydroxyl radical(·OH), catalase(CAT), peroxidase(POD) and lipoxygenase(LOX) were explored. The results showed that, the UV-Vis spectral absorption of capsanthin treated with reactive oxygen species had a blue-shift. At the same time, the FTIR spectra changed significantly. The number of FTIR spectral peaks reduced and theFTIR strength weakened for capsanthin molecule treated with ·O-2 and ·OH. The characteristic and strong peaks moved to shorter wavelengths when treated with H2O2. And LOX caused breakage of capsanthin molecule and reduction of peak number or groups without carbonyl. Exogenous H2O2+CAT or H2O2+POD treatment could not affect the UV-Vis and FTIR spectra significantly. So ROS could cause oxidative degradation of capsanthin and destroy chromophoric groups such as carbon-carbon double bond and carbonyl, then grow colorless alcohols. Hence ROS and LOX should transforms the conjugate system of capsanthin molecules, while CAT and POD could protect the capsanthin..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 358 (2014)
Progress in Retrieving Land Surface Temperature for the Cloud-Covered Pixels from Thermal Infrared Remote Sensing Data
ZHOU Yi, QIN Zhi-hao, and BAO Gang
Land surface temperature (LST), which reflects surface properties, is one of the key parameters in the physics of land surface processes from local through global scales. LST is very required in time and space for a wide variety of scientific studies and thermal infrared (TIR) remote sensing applications. Satellite TIRLand surface temperature (LST), which reflects surface properties, is one of the key parameters in the physics of land surface processes from local through global scales. LST is very required in time and space for a wide variety of scientific studies and thermal infrared (TIR) remote sensing applications. Satellite TIR channels are very available for LST retrieval but only in clear skies. However, when the surface is obscured by clouds, the actual retrieved LST for the corresponding pixel is, or is contaminated by, the cloud top temperature. Lacking understanding of the complex relationships between clouds and LST, the estimation of LST for cloud-covered pixels poses a big problem and challenge for thermal remote sensing scientists. In the present paper, a review of algorithms and approaches related to LST retrieval for cloud-covered pixels from TIR data is presented, and the characteristics of each method are also discussed. Directions for future research to improve the accuracy of satellite-derived LST for cloud-covered pixels are then suggested..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 364 (2014)
Determination of the Content of Sulfur of Coal by the Infrared Absorption Method with High Acccuracy
WANG Hai-feng, LU Hai, LI Jia, SUN Guo-hua, WANG Jun, and DAI Xin-hua
The present paper reported the differential scanning calorimetry-thermogravimetry curves and the infrared (IR) absorption spectrometry under the temperature program analyzed by the combined simultaneous thermal analysis-IR spectrometer. The gas products of coal were identified by the IR spectrometry. This paper emphasiThe present paper reported the differential scanning calorimetry-thermogravimetry curves and the infrared (IR) absorption spectrometry under the temperature program analyzed by the combined simultaneous thermal analysis-IR spectrometer. The gas products of coal were identified by the IR spectrometry. This paper emphasized on the combustion at high temperature-IR absorption method, a convenient and accurate method, which measures the content of sulfur in coal indirectly through the determination of the content of sulfur dioxide in the mixed gas products by IR absorption. It was demonstrated, when the instrument was calibrated by varied pure compounds containing sulfur and certified reference materials (CRMs) for coal, that there was a large deviation in the measured sulfur contents. It indicates that the difference in chemical speciations of sulfur between CRMs and the analyte results in a systematic error. The time-IR absorption curve was utilized to analyze the composition of sulfur at low temperatures and high temperatures and then the sulfur content of coal sample was determined by using a CRM for coal with a close composition of sulfur. Therefore, the systematic error due to the difference in chemical speciations of sulfur between the CRM and analyte was eliminated. On the other hand, in this combustion at high temperature-IR absorption method, the mass of CRM and analyte were adjusted to assure the sulfur mass equal and then the CRM and the analyte were measured alternately. This single-point calibration method reduced the effect of the drift of the IR detector and improved the repeatability of results, compared with the conventional multi-point calibration method using the calibration curves of signal intensity vs sulfur mass. The sulfur content results and their standard deviations of an anthracite coal and a bituminous coal with a low sulfur content determined by this modified method were 0.345% (0.004%) and 0.372% (0.008%), respectively. The uncertainty (U, k=2) of sulfur contents of two coal samples was evaluated to be 0.019% and 0.021%, respectively. Two main modifications, namely the calibration using the coal CRM with a similar composition of low-temperature sulfur and high temperature sulfur, and the single-point calibration alternating CRM and analyte, endow the combustion at high temperature-IR absorption method with an accuracy obviously better than that of the ASTM method. Therefore, this modified method has a well potential in the analysis of sulfur content..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 370 (2014)
Analysis and Identification of Poria Cocos Peels Harvested form Different Producing Areas by FTIR and 2D-IR Correlation Spectroscopy
MA Fang, ZHANG Fang, TANG Jin, CHEN Ping, CHEN Jian-bo, ZHOU Qun, and SUN Su-qin
Different geographical regions of traditional Chinese medicine (TCM), its chemical composition is different, the accumulation of drug and medicinal properties is different. The accurate identification and analysis of different production area of medicinal herbs is critical for the quality control and pharmacological reDifferent geographical regions of traditional Chinese medicine (TCM), its chemical composition is different, the accumulation of drug and medicinal properties is different. The accurate identification and analysis of different production area of medicinal herbs is critical for the quality control and pharmacological research of TCM. In this paper, a tri-step infrared spectroscopy (Fourier transform infrared spectroscopy (FTIR) combined with second derivative spectra and two-dimensional correlation infrared spectroscopy (2D-COS) were employed to identify and analyze the main components of Hubei(HB), Anhui(AH), Yunnan(YN) genuine Poria Cocos peels. The emergence of several characteristic absorption peaks of carbohydrates including 1 149, 1 079 1 036 cm-1, peaks around 1 619, 1 315, 780 cm-1 belonged to calcium oxalate suggested that HB and AH Poria Cocos peels contained calcium oxalate, but peaks around 797, 779, 537, 470 cm-1 belonged to kaoline suggested that YN Poria Cocos peels contained kaoline. Their carbohydrates were different by comparing the second derivative infrared spectra in the range of 1 640～450 cm-1 and Yongping come from YN contains both calcium oxalate and kaoline. Furthermore, the above differences were visually validated by two-dimensional correlation spectroscopy (2D-COS). It was demonstrated that the Tri-step infrared spectroscopy were successfully applied to fast analyze and identify Poria Cocos peels from different geographical regions and subsequently would be applicable to explain the relevance of geographical regions and medicinal properties for the TCM..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 376 (2014)
Non-Destructive Brand Identification of Car Wax Using Visible and Near-Infrared Spectroscopy
ZHANG Yu, TAN Li-hong, and HE Yong
Visible and near-infrared (Vis-NIR) spectroscopy was applied to identify brands of car wax. A total of 104 samples were obtained for the analysis, in which 40 samples (calibration set) were used for model calibration, and the remaining 64 samples (prediction set) were used to validate the calibrated model independentlyVisible and near-infrared (Vis-NIR) spectroscopy was applied to identify brands of car wax. A total of 104 samples were obtained for the analysis, in which 40 samples (calibration set) were used for model calibration, and the remaining 64 samples (prediction set) were used to validate the calibrated model independently. Linear discriminant analysis (LDA) and least square-support vector machine (LS-SVM) were respectively used to establish identification models for car wax with five brands based on their Vis-NIR spectra. Correct rates for prediction sample set were 84% and 97% for LDA and LS-SVM models, respectively. Spectral variable selection was further conducted by successive projections algorithm, (SPA), resulting in seven feature variables (351, 365, 401, 441, 605, 926, and 980 nm) selected from full range spectra that had 751 variables. The new LS-SVM model established using the feature variables selected by SPA also had the correct rate of 97%, showing that the selected variables had the most important information for brand identification, while other variables with no useful information were eliminated efficiently. The use of SPA and LS-SVM could not only obtain a high correct identification rate, but also simplify the model calibration and calculation. SPA-LS-SVM model could extract the useful information from the Vis-NIR spectra of car wax rapidly and accurately for the non-destructive brand identification of car wax..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 381 (2014)
Structural Characterization and Spectroscopic Analysis of the Aloin
XIE Yun-fei, HUAN Nan, CAO Yuan-yuan, WANG He-ya, ZHONG Ying, YAO Wei-rong, and QIAN He
Aloe is widely used in various fields for its rich polysaccharides, proteins, amino acids, vitamins, active enzymes and trace beneficial elements to human body. However, the main active ingredient aloin is also an allergenic ingredient, which even may cause a severe allergic reaction. In this study, infrared spectroscoAloe is widely used in various fields for its rich polysaccharides, proteins, amino acids, vitamins, active enzymes and trace beneficial elements to human body. However, the main active ingredient aloin is also an allergenic ingredient, which even may cause a severe allergic reaction. In this study, infrared spectroscopy, Raman spectroscopy applied to the structural characterization of the aloin. Density functional theory (DFT) is applied to the theoretical calculations using the B3LYP/6-31G (d) basis set vibration, which was helpful to understand the aloin molecular vibrational frequency. By comparing we choose the optimal experimental condition for water as solvent under alkaline conditions, the detection limit of the Aloin can reach a level of 5 ppm, which can be considered the theoretical basis for rapid detection of aloin content..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 385 (2014)
Detection of Chlorophyll Content in Water Body Based on Two-Dimensional Correlation Spectroscopy
ZHANG Yao, ZHENG Li-hua, SUN Hong, and LI Min-zan
Twenty five samples were collected from 10 different ponds in Jiangsu Province of China. According to the different water status and surface area of each pond, different numbers of water samples were collected. The present paper aims to detect chlorophyll content in water body based on hyperspectrum. The visible and neTwenty five samples were collected from 10 different ponds in Jiangsu Province of China. According to the different water status and surface area of each pond, different numbers of water samples were collected. The present paper aims to detect chlorophyll content in water body based on hyperspectrum. The visible and near infrared spectral transmittance of the water samples was measured by using a Shimadzu UV-2450 spectrograph. At the same time, the chlorophyll content of each sample was measured using hot-ethanol extraction method in the laboratory. Then the spectral characteristics were analyzed for the water samples and the results showed that with chlorophyll concentration increasing, spectral transmittance decreased gradually. There is an apparent transmission valley at 676 nm. And then two dimensional correlation spectrum technology was used to analyze the sensitive absorption band of chlorophyll in water body. Comprehensive observation of the spectral characteristics of water samples can be carried out much accurately by analyzing two-dimensional correlation spectra of synchronous and asynchronous spectrograms. And the effective spectral response bands of the chlorophyll content were found at 488 and 676 nm. Then the NDWCI (normalized difference water chlorophyll index) was established with the transmittance of red band and blue band. Two regression models were built to predict the chlorophyll concentration in water. One is a multiple linear regression model based on the original transmittances at 488 and 676 nm. The other is the linear regression model based on NDWCI. By comparison, the model based on NDWCI was better. The R2 of its training model reached to 0.771 2, and the root mean square error of calibration was 45.509 9 mg·L-1. The R2 of prediction model reached to 0.765 8, and the root mean square error of prediction was 39.503 8 mg·L-1. It reached to a practical level to predict the chlorophyll content in water body rapidly..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 389 (2014)
Research on the Temperature Field Detection Method of Hot Forging Based on Long-Wavelength Infrared Spectrum
ZHANG Yu-cun, WEI Bin, and FU Xian-bin
A temperature field detection method based on long-wavelength infrared spectrum for hot forging is proposed in the present paper. This method combines primary spectrum pyrometry and three-stage FP-cavity LCTF. By optimizing the solutions of three group nonlinear equations in the mathematical model of temperature detectA temperature field detection method based on long-wavelength infrared spectrum for hot forging is proposed in the present paper. This method combines primary spectrum pyrometry and three-stage FP-cavity LCTF. By optimizing the solutions of three group nonlinear equations in the mathematical model of temperature detection, the errors are reduced, thus measuring results will be more objective and accurate.Then the system of three-stage FP-cavity LCTF was designed on the principle of crystal birefringence. The system realized rapid selection of any wavelength in a certain wavelength range. It makes the response of the temperature measuring system rapid and accurate. As a result, without the emissivity of hot forging, the method can acquire exact information of temperature field and effectively suppress the background light radiation around the hot forging and ambient light that impact the temperature detection accuracy. Finally, the results of MATLAB showed that the infrared spectroscopy through the three-stage FP-cavity LCTF could meet the requirements of design. And experiments verified the feasibility of temperature measuring method. Compared with traditional single-band thermal infrared imager, the accuracy of measuring result was improved..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 394 (2014)
Determination of the Carboxyl Content of Oxidized Starch by Fourier Transform Infrared (FTIR) Spectroscopy
DING Long-long, ZHANG Yan-hua, GU Ji-you, TAN Hai-yan, and ZHU Li-bin
In the present study, the carboxyl content of oxidized starch was determined by FTIR spectroscopy. Standard curve was drawn in which the ordinate was carboxyl content determined by national standard method with the ratio of carbonyl absorbance to the key of C—H absorbance in FTIR spectroscopy as the abscissa. The ratioIn the present study, the carboxyl content of oxidized starch was determined by FTIR spectroscopy. Standard curve was drawn in which the ordinate was carboxyl content determined by national standard method with the ratio of carbonyl absorbance to the key of C—H absorbance in FTIR spectroscopy as the abscissa. The ratio of absorbance of unknown oxidized starch tested by FTIR spectroscopy was obtained, The carboxyl content was calculated by standard curve, and then compared with the carboxyl content determined by national standard method, and the deviation is between 2% and 4%. In order to improve the accuracy of the experiment，standard sample was selected to draw standard curve to better ensure that the carboxyl content of the unknown oxidized starch is in the range of standard curve calculation limit, and deviates from the limit of standard curve. Compared with the carboxyl content determined by national standard method, testing with FTIR spectroscopy is simple, easy to operate, and of high efficiency and better accuracy. So, it is significant to forecast the carboxyl content of oxidized starch by FTIR spectroscopy..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 401 (2014)
Raman and Infrared Spectra of Non-Stoichiometry Uranium Oxides
Lv Jun-bo, LI Gan, and GUO Shu-lan
Both of Raman and infrared spectra of seven non-stoichiometry and threestoichiometry uranium oxides， including UO2, U3O7 and UO2+x（0＜x＜0.66）, are presented and discussed. The spectra of UO2+x in the stoichiometry range, U3O7 to U3O8, were first obtained and reported. Three typical peaks were observed at 445, 578 and 1 Both of Raman and infrared spectra of seven non-stoichiometry and threestoichiometry uranium oxides， including UO2, U3O7 and UO2+x（0＜x＜0.66）, are presented and discussed. The spectra of UO2+x in the stoichiometry range, U3O7 to U3O8, were first obtained and reported. Three typical peaks were observed at 445, 578 and 1 150 cm-1 in the Raman spectrum of uranium dioxide. The intensities of the peaks at 578 and 1 151 cm-1 decrease quickly with increasing x value of UO2+x, and while x=0.19, the two peaks disappear. Such peaks can therefore be considered as a fin-gerprint of the quasi-perfect UO2 fluorite structure. The peak at 445 cm-1 tends to weaken, broaden and shift to higher wavenumber in more oxidised samples. When x=0.32, this peak is shifted to the 459 cm-1 and a weak peak at about 630 cm-1 appears. The two new peaks are typical of the tetragonal U3O7. While x≥0.39, the peak at 459 cm-1 further splits into separate components. Two peaks at 235 and 754 cm-1 appear for UO2.39 and are visible with increased intensity as the oxygen-uranium ratio is increased. And the Raman spectra of UO2+x are gradually close to U3O8 in the α-phase, which has an orthorhombic unit cell. But several strongest features of theα-U3O8 specturm at 333, 397, 483 and 805 cm-1 are still not outstanding even in UO2.60. The main feature of the UO2 infrared spectrum shows a very broad and strong adsorption band at 400～570 cm-1 and another feature is a weak adsorption peak at about 700 cm-1. The 400～570 cm-1 band undergoes a progressive splitting into two new peaks at ～421 and ～515 cm-1 through increasing incorporation of oxygen into UO2. The weak peak at about 700 cm-1 disappears and a new weak peak appears at about 645 cm-1. The three new peaks are the infrared absorption features of U3O7. An absorption peak at 744 cm-1 which is the strongest feature ofα-U3O8 infrared spectrum appears for UO2.39 and is visible with increased intensity in more oxidised samples. The peak at about 645 cm-1 still exists and 515 cm-1 peak has no further splitting into two new peaks at 485 and 535 cm-1 which also are the infrared absorption features of U3O8 in UO2.60. This indicates that UO2.60 is still in the transition period between tetragonal and orthorhombic phase of uranium oxide. A sequence of phase transitions occurs through increasing x value of UO2+x with different Raman and infrared features.It is easy to identify different uranium oxides by comparing of relative intensities and locations of their characteristic peaks..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 405 (2014)
Raman and DSC Spectroscopic Studies on the Interaction between Ginsenosides and DMPC Bilayer Membranes
HUI Ge, ZHAO Yu, ZHANG Jing-zhou, LIU Wei, LI Hong-dong, and ZHAO Bing
Study the effect of drugs and biological membranes is of prime importance on understanding drugs’ curative effects and improving their biological properties. In this article, Raman spectrum has been combined with differential thermal scanning technology to discuss the relationship between five categories of ginsenosideStudy the effect of drugs and biological membranes is of prime importance on understanding drugs’ curative effects and improving their biological properties. In this article, Raman spectrum has been combined with differential thermal scanning technology to discuss the relationship between five categories of ginsenoside molecules and DMPC bilayer films. Raman results indicated that the saponin molecules have not altered the polarity conformation of O—C—C—N+ backbone in DMPC bilayers, and the polarity head still paralleled to the membrane surface. The order of the internal molecular chain and the lateral chain-chain packing have been decreased as the panaxadiol saponins Rb1 and Rh2 increased, and to the opposite, the panaxatriol saponins Re, Rf and Rg1have showed weak effects on DMPC bilayers. The DSC showed further results that the strong effects of ginsenoside Rb1 and Rh2 on DMPC, which both have obviously reduced the DMPC molecular phase transition temperature, thus increasing the fluidity of bilayers. In addition, panaxatriol saponin Rf has displayed stronger disturbance effect on DMPC than Re and Rg1..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 410 (2014)
Raman Spectra Characteristics of Alunite in the Zijinshan Gold-Copper Deposit
WANG Cui-zhi, and XIONG Xin
The Zijinshan gold-copper deposit is the first one of high sulfidation epithermal hydrothermal deposits. The gold bodies up, and the copper bodies down. The gold bodies mainly occur above the ground water table associated with strong silicification, and the copper bodies mainly occur below the ground water table associThe Zijinshan gold-copper deposit is the first one of high sulfidation epithermal hydrothermal deposits. The gold bodies up, and the copper bodies down. The gold bodies mainly occur above the ground water table associated with strong silicification, and the copper bodies mainly occur below the ground water table associated with alunitization. The alunite of the Zijinshan gold-copper deposit has four types of occurrence status, that is the altered rock type, the intergrowth-with-Cu-sulphide type, the vein type and the powder type. Different types of the alunite are of different Raman spectra characteristics and fluorescence scattering background. Laser Raman spectra of inclusions in the alunite show that: (1) The characteristics of the Laser Raman spectra of the alunite are of characteristic spectral bands of alunite, just fluorescent scattering weaken gradually from the altered rock type, the intergrowth-with-Cu-sulphide type to the vein type; the alunite in the Powder type has different bands of the Laser Raman spectra relative to the former three types, the intensity of each band is weaker, and it’s fluorescent scattering intensity is strongger. (2) The bands in 100～700 cm－1 of the Laser Raman spectra can be used as "fingerprint" bands indicating the condition of the cation replacement in the molecular structure of alunite. The intensities at 161 and 234 peak change obviously in the bands of the alunite in the altered rock type, which indicating a wide replacement between K and Na; the intensities at 381 and 484 peak in the bands of the alunite in the intergrowth-with-Cu-sulphide type change significantly, indicating Al can be replaced with Cu, Ga, etc.; the larger and stable intensities of the alunite in the vein type in the bands at the peaks about 161, 234, 484, 508, etc. indicate that there are less chances with the replacement between K and Na, Al and Si; fluorescence scatorescent scattering is very strong and the intensity of each band is weaker in the bands of the alunite in the powder type, which indicate that the alunite formed in the underground water condition. (3) The laser Raman spectra of the alunite can be used together with it’s infrared spectra, and provide the characteristics of complete vibration spectra of the alunite and the structure information with the mineral research. Based on the mineralography, the petrography, the ore deposit geology, the geochemistry of mineral deposits, the regional geological features, the Laser Raman spectra of the alunite (Combined with fluorescence scattering background) can further the evolution process for the Zijinshan gold-copper deposit as a typical high sulfidation epithermal hydrothermal deposit..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 415 (2014)
Density Functional Theory Study of Surface-Enhanced Raman Spectra and Excited State of 1,4-Benzenedithiol
SHAO Yang-fan, LI Chong-yang, FENG Yuan-ming, and LIN Wang
Raman scattering spectra and optimized geometries of the 1,4-benzenedithiol molecule and complexes have been calculated using density functional theory (DFT) with B3LYP functional at the level of 6-311G+(d) basis set for C,H,S atoms and LanL2DZ for Ag， Au atoms， respectively. The optimized 1,4-benzenedithiol molecule wRaman scattering spectra and optimized geometries of the 1,4-benzenedithiol molecule and complexes have been calculated using density functional theory (DFT) with B3LYP functional at the level of 6-311G+(d) basis set for C,H,S atoms and LanL2DZ for Ag， Au atoms， respectively. The optimized 1,4-benzenedithiol molecule was non-planar structure and the angle between benzene ring plane and S—H is 20. 20. By means of the simulation of molecule adsorbed on gold and silver cluster， we concluded that gold clusters are nearly parallel to the benzenedithiol molecule and silver clusters are almost perpendicular to the molecular surface. The authors studied the interaction between Raman intensity and molecular properties， such as static polarizablity and charge distribution. The Raman intensity of 1,4-BDT-Au2， 1,4-BDT-Ag2 and Ag2-1,4-BDT-Au2 were in good agreement with static polarizability. The excited states of Ag2-1,4-BDT-Au2 complex were calculated using time-dependent density functional theory (TDDFT). And the simulated absorption spectra and several allowed singlet excited states were analyzed to investigate the surface-enhanced Raman chemical enhancement mechanism..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 421 (2014)
Combined Use of Infrared and Raman Spectra in the Characterization of Orthoclase under Various Hydrostatic Pressures
LIU Rui, WANG Zhi-hua, XU Qiang, YU Na, and CAO Miao-cong
Colorless and pink orthoclase from Balikun granite body, East Zhunger in Xinjiang, served as the samples for the research on hydrostatic pressure experiment. The in-situ hydrostatic pressure test for orthoclases was conducted at the room temperature and pressures from 100 to 600 MPa using cubic zirconia anvil cell, witColorless and pink orthoclase from Balikun granite body, East Zhunger in Xinjiang, served as the samples for the research on hydrostatic pressure experiment. The in-situ hydrostatic pressure test for orthoclases was conducted at the room temperature and pressures from 100 to 600 MPa using cubic zirconia anvil cell, with quartz as pressure gauge. The water located in the orthoclases for the conditions of different hydrostatic pressures was characterized through the methods of Fourier transform infrared (FTIR) and Raman spectra. The results showed that there was a linear correlation between the shifting of Raman bands and hydrostatic pressure applied to the feldspar. All of vibration peaks of M—O structural groups in orthoclases，the bending vibration peaks of Si(AlⅣ)—O—Si bond and tetrahedron groups of ［SiO4］ in Raman spectra shifted toward the higher frequency regularly, the drift distance is 2, 2.19 and less than 2 cm-1 respectively. The spectra of FTIR suggested that there was more water in colorless orthoclases than the pink one under certain conditions of hydrostatic pressure. The intensity and integral area centered at 3 420 cm-1 in FTIR spectra increased with the rising of hydrostatic pressure. The integral area for colorless and pink feldspar in FTIR spectra rose from 120， 1 383 cm-1 under normal pressure to 1 570， 2 001 cm-1 at 600 MPa respectively. The experimental results might indicate that the water in the earth crust could enter the orthoclases in certain condition of the aqueous confining pressure..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 426 (2014)
Research on the Surface-Enhanced Raman Spectrum of Sodium Sulfide Nonahydrate and Its Application in Monosodium Glutamate Detecting
JIA Bao-shen, Hasi Wuliji, LIN Xiang, YANG Fang, and Lv Zhi-wei
The surface-enhanced Raman spectrum of sodium sulfide was studied and the structure vibration information was obtained. The raman characteristic peak at 472 cm-1 was selected to evaluate enhanced effects. Gold colloid was used as active substrate, The relationship between gold nanoparticle size and enhanced efficiency The surface-enhanced Raman spectrum of sodium sulfide was studied and the structure vibration information was obtained. The raman characteristic peak at 472 cm-1 was selected to evaluate enhanced effects. Gold colloid was used as active substrate, The relationship between gold nanoparticle size and enhanced efficiency was analysised and the optimum size for SERS is 97 nm. The surface enhanced Raman scattering spectra of sodium sulfide at different concentrations were also presented. The results indicated that SERS spectra of sodium sulfide can be found even the concentration reach 10-6 g·mL-1. The performance of active substrate is related with the ratio of sample and gold colloid. In the real situation, 1 g monosodium glutamate was added to 10mL sodium sulfide solution with different concentration and then SERS spectra of these samples were collected respectively. The lever of qualitative detection can reach 10mg·kg-1. And due to the simple procedure in sample preparation, this method is of great potential in on-line qualitative detection..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 431 (2014)
Laser Raman Spectra Study on Co-Mo/Al2O3 Hydrodesulphurization Catalysts
YUAN Hui, XU Guang-tong, Qiherima, LI Hui-feng, LU Li-jun, YANG Xing-yuan, and Tana
Due to the implementation of more stringent specifications in sulfur content for gasoline , a deep understanding of the active phase of Co-Mo/Al2O3 catalysts is necessary to the development of hydrodesulphurization (HDS) catalysts. A series of Co-Mo/Al2O3 HDS catalysts with different metal loading were studied by laserDue to the implementation of more stringent specifications in sulfur content for gasoline , a deep understanding of the active phase of Co-Mo/Al2O3 catalysts is necessary to the development of hydrodesulphurization (HDS) catalysts. A series of Co-Mo/Al2O3 HDS catalysts with different metal loading were studied by laser Raman spectra. The existence form and the content of the active component of the catalyst were obtained by Raman spectra. The result shows that the percentage of characteristic Raman bands 940 cm-1 correlates linearly with the HDS selectivity, which can be used as an experimental evidence for developing industrial selective HDS catalysts. Raman spectra of sulfided catalysts show that the bands of oxidic catalysts at 839 and 940 cm-1 disappeared, and simultaneously, the bands of Mo—S at 372 and 408 cm-1 emerged, which indicate that the oxidic sample is sulfided completely..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 435 (2014)
Application of Raman Spectroscopy to the Research on Hemoglobin Structure and Function
LU Ming-zi, GUO Yan-jun, ZHAO Lian, and ZHOU Hong
Hemoglobin plays many significant biological roles in organism. However, our knowledge about its structure and function is not enough to meet the demand of clinical diagnosis. Raman spectroscopy has been shown to be an attractive optical technique which can provide direct access to the structure and function of hemogloHemoglobin plays many significant biological roles in organism. However, our knowledge about its structure and function is not enough to meet the demand of clinical diagnosis. Raman spectroscopy has been shown to be an attractive optical technique which can provide direct access to the structure and function of hemoglobin. It is a proven tool for elucidating structural information of hemes and other vicinal groups. Furthermore, it can provide a useful monitor for hemoglobin dynamics. Besides, Raman spectroscopy has notable advantages in the fields of abnormal hemoglobin diagnosis, hemoglobin oxygen saturation determination and blood methemoglobin analysis. The present paper reviews the research on hemoglobin structure and function using Raman spectroscopy and the application in hemoglobinopathy diagnosis. In addition, we discuss the factors affecting the measurement in Raman spectroscopy of hemoglobin. The aim of the review is to promote the application of Raman spectroscopy to the research of hemoglobin structure and function..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 439 (2014)
Mn2+-CTMAB-Sensitized Fluorescent Microscopic Determination of Tosufloxacin Tosylate Based on a Self-Ordered Ring
DENG Feng-yu, HUANG Chun-xiu, and LIU Ying
With the development of antimicrobial drugs, drug residue in animal products has a serious potential hazards for the environment and public health, it is urgent to set up drug residue detection method with low detection limit and good selectivity. In our paper, with poly (vinyl alcohol)-124 (PVA-124) and NH3-NH4Cl (pH With the development of antimicrobial drugs, drug residue in animal products has a serious potential hazards for the environment and public health, it is urgent to set up drug residue detection method with low detection limit and good selectivity. In our paper, with poly (vinyl alcohol)-124 (PVA-124) and NH3-NH4Cl (pH 10.50) as the medium, Mn2+ and cetyltrimethyl ammonium bromide (CTMAB) as sensitizer, tosufloxacin tosylate (TSFX) formed a self-ordered ring (SOR) on a hydrophobic glass slide support. When the droplet volume is 0.20 μL, the TSFX can be detected in the range of 4.05×10-14～4.28×10-13 mol·ring-1 (2.02×10-7～2. 14×10-6 mol·L-1), and the limit of detection (LOD) can reach 4.1×10-15 mol·ring-1 (2.0×10-8 mol·L-1). The established method had been applied satisfactorily to determine the content of TSFX in tablet, which close to the marked value of 0.15 g·piece-1) found value: 0.144 g·piece-1) and the results of TSFX concentrations in rabbit serum at different time after dosing with the recoveries of 90.0%～105.0% and RSDs 1.9%～3.3% were satisfactory. Xilinguole of Inner Mongolia is the national important livestock products ground, whose lamb is the main suppling source for Beijing-Tianjin-Tangshan region. It is very urgent to detect residue of antibacterial drug in its sheep tissue samples (meat, liver, kidney). In this paper, when acetonitrile was used as extraction agent in pretreatment of sheep tissue samples in six rangelands including Sonid Right Banner, Xiwuzhumuqin Banner, Xilinhot City, Duolun County, The white Flag Town and The Blue Flag Town, the extract can be directly determined with SOR technology without filtering process, the sample standard addition recovery of sheep tissues were 92.0%～101.0% and RSDs were less than 2.7%. The results indicated that the SOR technique can be successfully applied to pharmaceuticals and biological samples, which broaden the applied range of SOR technique. The assay would provide reliable experimental data and theoretical basis for the relevant departments..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 445 (2014)
Analysis of Dissolved Organic Matters in Fu River of Baoding Using Three Dimensional Fluorescence Excitation-Emission Matrix
TANG Jing-mei, LIANG Shu-xuan, SUN Han-wen, LIU Shan, and WANG Li-hua
The fluorescence properties of dissolved organic matter (DOM) in Fu River in Baoding were investigated by three-dimensional fluorescence spectrometry. The type, distribution and origin of the DOM were estimated on basis of the position, number and intensity of fluorescence peaks in the spectra. Two types of fluorescencThe fluorescence properties of dissolved organic matter (DOM) in Fu River in Baoding were investigated by three-dimensional fluorescence spectrometry. The type, distribution and origin of the DOM were estimated on basis of the position, number and intensity of fluorescence peaks in the spectra. Two types of fluorescence peaks were detected from Fu River. There are protein-like fluorescence peaks A with Ex/Em=225～230/340 nm and soluble microbial metabolites peaks B with Ex/Em=275/340～350 nm. The protein-like fluorescence peaks and soluble microbial metabolites peaks were founded in different times and stations in Fu River. Certain correlation was observed between the fluorescence intensity of DOM and the water quality parameters of Fu River. Good correlation of different fluorescence peaks showed the same of source. The fluorescence intensity of the two types had a significant positive relationship with COD, TN, TP and NH3-N concentration, this phenomenon indicating that the fluorescence peaks can speculate the level of pollution of Fu River. These results provided a reference for the pollution control in Fu River..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 450 (2014)
Change in Soil Enzymes Activities after Adding Biochar or Straw by Fluorescent Microplate Method
ZHANG Yu-lan, CHEN Li-jun, DUAN Zheng-hu, WU Zhi-jie, SUN Cai-xia, and WANG Jun-yu
The present work was aimed to study soil α-glucosidase and β-glucosidase activities of and red soils based on fluorescence detection method combined with 96 microplates with TECAN Infinite 200 Multi-Mode Microplate Reader. We added biochar or straw (2.5 g air dry sample/50g air dry soil sample) into and red soils and tThe present work was aimed to study soil α-glucosidase and β-glucosidase activities of and red soils based on fluorescence detection method combined with 96 microplates with TECAN Infinite 200 Multi-Mode Microplate Reader. We added biochar or straw (2.5 g air dry sample/50g air dry soil sample) into and red soils and the test was carried under fixed temperature and humidity condition (25 ℃, 20% soil moisture content). The results showed that straw addition enhances soil α- glucosidase and β-glucosidase activities, β-glucosidase activity stimulated by rice straw treatment was higher than that of corn straw treatment, and activity still maintains strong after 40 days, accounting for increasing soil carbon transformation with straw inputting. Straw inputting increased soil nutrients contents and may promote microbial activity, which also lead to the increase oin enzyme activities. Different effects of straw kinds may be related to material source that needs further research. However, biochar inputting has little effect on soil α- glucosidase and β- glucosidase activity. Biochar contains less available nutrients than straw and have degradation-resistant characteristics. Compared with the conventional spectrophotometric method, fluorescence microplate method is more sensitive to soil enzyme activities in suspension liquid, which can be used in a large number of samples. In brief, fluorescence microplate method is fast, accurate, and simple to determine soil enzymes activities..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 455 (2014)
Photocatalytic Degradation of Imidacloprid by Composite Catalysts H3PW12O40/La-N-TiO2 under Visible Light
LIU Xia, XU Gang, and FENG Chang-gen
Catalysts H3PW12O40/La-N-TiO2 were prepared and characterized by FT-IR, N2 adsorption-desorption analysis, SEM and UV-Vis diffuse reflection spectrum (DRS). It was demonstrated that Keggin structure of H3PW12O40 retained in composite materials by the FT-IR test; After doping La-N, the BET surface area of them is nearlyCatalysts H3PW12O40/La-N-TiO2 were prepared and characterized by FT-IR, N2 adsorption-desorption analysis, SEM and UV-Vis diffuse reflection spectrum (DRS). It was demonstrated that Keggin structure of H3PW12O40 retained in composite materials by the FT-IR test; After doping La-N, the BET surface area of them is nearly 2 times as that of pure TiO2; the SEM images of the catalysts revealed that they were consist of relatively uniform spherical grains with good dispersion; UV-Vis DRS showed the photoresponse performance of the prepared composites for the visible light area were improved after doping La and N. The prepared composites were used as photocatalysts in degradation of pesticide imidacloprid. Results revealed that 30%H3PW12O40/0.3%La-1.0%N-TiO2 possessed the best photocatalytic activity under visible light above 400 nm. Thus, imidacloprid were degraded 91.57% after 3 h irradiation. When 30%H3PW12O40/0.3%La-1.0%N-TiO2 was used as catalysts, degradation ration could even reach 98.89% after 6 h..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 460 (2014)
An Automatic Extraction Algorithm for Individual Tree Crown Projection Area and Volume Based on 3D Point Cloud Data
XU Wei-heng, FENG Zhong-ke, SU Zhi-fang, XU Hui, JIAO You-quan, and DENG Ou
Tree crown projection area and crown volume are the important parameters for the estimation of biomass， tridimensional green biomass and other forestry science applications. Using conventional measurements of tree crown projection area and crown volume will produce a large area of errors in the view of practical situatTree crown projection area and crown volume are the important parameters for the estimation of biomass， tridimensional green biomass and other forestry science applications. Using conventional measurements of tree crown projection area and crown volume will produce a large area of errors in the view of practical situations referring to complicated tree crown structures or different morphological characteristics. However, it is difficult to measure and validate their accuracy through conventional measurement methods. In view of practical problems which include complicated tree crown structure, different morphological characteristics, so as to implement the objective that tree crown projection and crown volume can be extracted by computer program automatically. This paper proposes an automatic untouched measurement based on terrestrial three-dimensional laser scanner named FARO Photon120 using plane scattered data point convex hull algorithm and slice segmentation and accumulation algorithm to calculate the tree crown projection area. It is exploited on VC+6.0 and Matlab7.0. The experiments are exploited on 22 common tree species of Beijing, China. The results show that the correlation coefficient of the crown projection between AV calculated by new method and conventional method A4 reaches 0.964(p<0.01); and the correlation coefficient of tree crown volume between VVC derived from new method and VC by the formula of a regular body is 0.960(p<0.001). The results also show that the average of VC is smaller than that of VVC at the rate of 8.03%, and the average of A4 is larger than that of AV at the rate of 25.5%. Assumed Av and VVC as ture values, the deviations of the new method could be attributed to irregularity of the crowns’ silhouettes. Different morphological characteristics of tree crown led to measurement error in forest simple plot survey. Based on the results, the paper proposes that: (1) the use of eight-point or sixteen-point projection with fixed angles to estimate crown projections, and (2) different regular volume formula to simulate crown volume according to the tree crown shapes. Based on the high-resolution 3D LIDAR point cloud data of individual tree, tree crown structure was reconstructed at a high rate of speed with high accuracy, and crown projection and volume of individual tree were extracted by this automatical untouched method, which can provide a reference for tree crown structure studies and be worth to popularize in the field of precision forestry..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 465 (2014)
Theoretical Analysis of the Residual Amplitude Modulation of Frequency Modulation Strong Absorption Spectroscopy
MA Wei-guang, LI Zhi-xin, TAN Wei, FU Xiao-fang, ZHAO Gang, DONG Lei, ZHANG Lei, YIN Wang-bao, and JIA Suo-tang
In the present paper a phase controllable waveplate model was applied to the analysis of polarization maintaining fiber. Under the temperatures of 24 ℃ and 26.8 ℃ there is no residual amplitude modulation (RAM) existing in frequency modulation spectroscopy (FMS) when performing the measurement of fiber temperature depeIn the present paper a phase controllable waveplate model was applied to the analysis of polarization maintaining fiber. Under the temperatures of 24 ℃ and 26.8 ℃ there is no residual amplitude modulation (RAM) existing in frequency modulation spectroscopy (FMS) when performing the measurement of fiber temperature dependence on the RAM. However, the temperature setting can not reduce the background long term drift and a servo feedback suggested by N. C. Wong and J. L. Hall can be used to actively reduce the RAM. The error signal for feedback is from the dispersion background signal of FMS without gas sample. The variation of RAM induced by the temperature changing of PM fiber is the main reason for the long term background drift of dispersion signal of FMS..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 472 (2014)
Estimation of Water Clarity in Offshore Marine Areas Based on Modified Semi-Analysis Spectra Model
HAN Liu-sheng, CHEN Shui-sen, CHEN Xiu-zhi, LI Dan, LI Yong, SUN Lin, LU Chu-qian, and CHEN Wei-qi
The main objectives of the research described in the present paper are to develop a semi-analysis model of water clarity for case 2 waters without inputting the absorption and scattering coefficient, which are not easy to be obtained for offshore marine areas so far. Based on the Zsd（Secchi depth）inversion theory, a siThe main objectives of the research described in the present paper are to develop a semi-analysis model of water clarity for case 2 waters without inputting the absorption and scattering coefficient, which are not easy to be obtained for offshore marine areas so far. Based on the Zsd（Secchi depth）inversion theory, a simple semi-analysis spectra model was established for offshore seawater clarity by analyzing the relationship between vertical diffuse attenuation coefficient Kd (490) and the beam attenuation coefficient c(490) with remote sensing reflectance. This semi-analysis spectra model needed two band reflectance ratios only, while tidal correction was produced for this model to improve the precision of the retrieving results. The semi-analysis spectra model was applied to ASD hyperspectral reflectance data measured in the Pearl River Estuary Ecological Zone (October 21, 23, 2012, November 2, 2012; N=20) and the Xuwen Coral Reef Protection Zone (January 13, 14, 2013, N=25) which covered different water body of tidal times and different pollution sources. The results indicated that the changing tendency of predicted values was consistent with the synchronous measurement values after comparing them. However, water clarity calculated by the ASD hyperspectral reflectance measured in spring tidal time, generated 0.4 m deviation compared with in-situ water clarity, while water clarity calculated by the ASD hyperspectral reflectance measured in neap tidal time is close to the in-situ water clarity. So the tidal correction coefficient of 0.4 was further applied for the model. After modification, the coefficient of determination between the inversed and measured water clarity was 0.663, the average absolute error was 0.14 m and the average relative error was 19.5%. Research demonstrated that this semi-analysis inversion algorithm just needs two band reflectance ratio to complete the inversion of water clarity, which is simple and works relatively well for lower clarity (less than 2 meters) waters compared to He’(2004) and Doron’(2011) algorithms..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 477 (2014)
Mechanism of Gold Solid Extraction from Aurocyanide Solution Using D3520 Resin Impregnated with TRPO
YANG Xiang-jun, WANG Shi-xiong, ZOU An-qin, CHEN Jing, and GUO Hong
Trialkyphosphine oxides (TRPO) was successfully used for the impregnation of D3520 resin to prepare an extractant-impregnated resin (EIR). Solid extraction of Au(Ⅰ) from alkaline cyanide solution was studied using this extractant-impregnated resin (EIR), with addition of cetyltrimethylammonium bromide (CTMAB), directlyTrialkyphosphine oxides (TRPO) was successfully used for the impregnation of D3520 resin to prepare an extractant-impregnated resin (EIR). Solid extraction of Au(Ⅰ) from alkaline cyanide solution was studied using this extractant-impregnated resin (EIR), with addition of cetyltrimethylammonium bromide (CTMAB), directly into the aurous aqueous phase in advance. The mechanism of solid extraction was further investigated by means of FTIR, XPS and SEM. The column separation studies have shown that cationic surfactant CTMAB played a key role in the solid phase extraction, and the resin containing TRPO were effective for the extraction of gold when the molar ratio of CTMAB:Au(Ⅰ) reached 1:1. FTIR spectroscopy of gold loaded EIR showed that the frequency of C≡N stretching vibration was at 2 144 cm-1, and the frequency of PO stretching vibration shifted to lower frequency from 1 153 to 1 150 cm-1. The XPS spectrum of N(1s)， Au(4f7/2) and Au(4f5/2) suggested that the coordination environment of gold did not change before and after extraction, and gold was still as the form of Au(CN)-2 anion exiting in the loaded resin; O(1s) spectrum showed that the chemically combined water significantly increased after solid extraction from 30.74% to 42.34%; Comparing to the P(2p) spectrum before and after extraction, the binding energy increased from 132.15 to 132.45 eV, indicating there maybe existing hydrogen-bond interaction between PO and water molecule, such as P=O…H—O—H. The above results obtained established that in the solid extraction process, the hydrophobic ion association ［CTMA+·Au(CN)-2］ diffused from the bulk solution into the pores of the EIR, and then be solvated by TRPO adsorbed in the pores through hydrogen bonding bridged by the water molecules..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 483 (2014)
Research on Universality of Least Squares Support Vector Machine Method for Estimating Leaf Area Index of Winter Wheat
XIE Qiao-yun, HUANG Wen-jiang, LIANG Dong, PENG Dai-liang, HUANG Lin-sheng, SONG Xiao-yu, ZHANG Dong-yan, and YANG Gui-jun
Leaf area index (LAI) is one of the most important parameters for evaluating winter wheat growth status and forecasting its yield. Hyperspectral remote sensing is a new technical approach that can be used to acquire the instant information of vegetation LAI at large scale. This study aims to explore the capability of lLeaf area index (LAI) is one of the most important parameters for evaluating winter wheat growth status and forecasting its yield. Hyperspectral remote sensing is a new technical approach that can be used to acquire the instant information of vegetation LAI at large scale. This study aims to explore the capability of least squares support vector machines (LS-SVM) method to winter wheat LAI estimation with hyperspectral data. After the compression of PHI airborne data with principal component analysis (PCA), the sample set based on the measured LAI data and hyperspectral reflectance data was established. Then the method of LS-SVM was developed respectively to estimate winter wheat LAI under four different conditions, to be specific, different plant type cultivars， different periods， different nitrogenous fertilizer and water conditions. Compared with traditional NDVI model estimation results, each experiment of LS-SVM model yielded higher determination coefficient as well as lower RMSE value, which meant that the LS-SVM method performed better than the NDVI method. In addition, NDVI model was unstable for winter wheat under the condition of different plant type cultivars， different nitrogenous fertilizer and different water, while the LS-SVM model showed good stability. Therefore, LS-SVM has high accuracy for learning and considerable universality for estimation of LAI of winter wheat under different conditions using hyperspectral data..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 489 (2014)
The Net Analyte Preprocessing Combined with Radial Basis Partial Least Squares Regression Applied in Noninvasive Measurement of Blood Glucose
LI Qing-bo, and HUANG Zheng-wei
In order to improve the prediction accuracy of quantitative analysis model in the near-infrared spectroscopy of blood glucose, this paper, by combining net analyte preprocessing(NAP) algorithm and radial basis functions partial least squares(RBFPLS) regression, builds a nonlinear model building method which is suitableIn order to improve the prediction accuracy of quantitative analysis model in the near-infrared spectroscopy of blood glucose, this paper, by combining net analyte preprocessing(NAP) algorithm and radial basis functions partial least squares(RBFPLS) regression, builds a nonlinear model building method which is suitable for glucose measurement of human, named as NAP-RBFPLS. First, NAP is used to pre-process the near-infrared spectroscopy of blood glucose, in order to effectively extract the information which only relates to glucose signal from the original near-infrared spectra, so that it could effectively weaken the occasional correlation problems of the glucose changes and the interference factors which are caused by the absorption of water, albumin, hemoglobin, fat and other components of the blood in human body, the change of temperature of human body, the drift of measuring instruments, the changes of measuring environment, and the changes of measuring conditions; and then a nonlinear quantitative analysis model is built with the near-infrared spectroscopy data after NAP, in order to solve the nonlinear relationship between glucose concentrations and near-infrared spectroscopy which is caused by body strong scattering. In this paper, the new method is compared with other three quantitative analysis models building on partial least squares(PLS)， net analyte preprocessing partial least squares(NAP-PLS) and RBFPLS respectively. At last, the experimental results show that the nonlinear calibration model, developed by combining NAP algorithm and RBFPLS regression, which was put forward in this paper, greatly improves the prediction accuracy of prediction sets， and what has been proved in this paper is that the nonlinear model building method will produce practical applications for the research of non-invasive detection techniques on human glucose concentrations..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 494 (2014)
Research on Fast Fourier Transforms Algorithm of Huge Remote Sensing Image Technology with GPU and Partitioning Technology
YANG Xue, LI Xue-you, LI Jia-guo, MA Jun, ZHANG Li, YANG Jan, and DU Quan-ye
Fast Fourier transforms (FFT) is a basic approach to remote sensing image processing. With the improvement of capacity of remote sensing image capture with the features of hyperspectrum, high spatial resolution and high temporal resolution, how to use FFT technology to efficiently process huge remote sensing image becoFast Fourier transforms (FFT) is a basic approach to remote sensing image processing. With the improvement of capacity of remote sensing image capture with the features of hyperspectrum, high spatial resolution and high temporal resolution, how to use FFT technology to efficiently process huge remote sensing image becomes the critical step and research hot spot of current image processing technology. FFT algorithm, one of the basic algorithms of image processing, can be used for stripe noise removal, image compression, image registration, etc. in processing remote sensing image. CUFFT function library is the FFT algorithm library based on CPU and FFTW. FFTW is a FFT algorithm developed based on CPU in PC platform, and is currently the fastest CPU based FFT algorithm function library. However there is a common problem that once the available memory or memory is less than the capacity of image, there will be out of memory or memory overflow when using the above two methods to realize image FFT arithmetic. To address this problem, a CPU and partitioning technology based Huge Remote Fast Fourier Transform (HRFFT) algorithm is proposed in this paper. By improving the FFT algorithm in CUFFT function library, the problem of out of memory and memory overflow is solved. Moreover, this method is proved rational by experiment combined with the CCD image of HJ-1A satellite. When applied to practical image processing, it improves effect of the image processing, speeds up the processing, which saves the time of computation and achieves sound result..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 498 (2014)
An Accurate Approach to Hyperspectral Mineral Identification Based on Naive Bayesian Classification Model
HE Jin-xin, CHEN Sheng-bo, WANG Yang, and WU Yan-fan
The spectral absorption features are very similar between some minerals, especially hydrothermal alteration minerals related to mineralization, and they are also influenced by other factors such as spectral mixture. As a result, many of the spectral identification approaches for the minerals with similar spectral absorThe spectral absorption features are very similar between some minerals, especially hydrothermal alteration minerals related to mineralization, and they are also influenced by other factors such as spectral mixture. As a result, many of the spectral identification approaches for the minerals with similar spectral absorption features are prone to confusion and misjudgment. Therefore, to solve the phenomenon of “same mineral has different spectrums, and same spectrum belongs to different minerals”, this paper proposes an accurate approach to hyperspectral mineral identification based on naive bayesian classification model. By testing and analyzing muscovite and kaolinite, the two typical alteration minerals, and comparing this approach with spectral angle matching, binary encoding and spectral feature fitting, the three popular spectral identification approaches, the results show that this approach can make more obvious differences among different minerals having similar spectrums, and has higher classification accuracy, since it is based on the position of absorption feature, absorption depth and the slope of continuum..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 505 (2014)
Comparative Study on Hyperspectral Inversion Accuracy of Soil Salt Content and Electrical Conductivity
PENG Jie, WANG Jia-qiang, XIANG Hong-ying, TENG Hong-fen, LIU Wei-yang, CHI Chun-ming, NIU Jian-long, GUO Yan, and SHI Zhou
The objective of the present article is to ascertain the mechanism of hyperspectral remote sensing monitoring for soil salinization, which is of great importance for improving the accuracy of hyperspectral remote sensing monitoring. Paddy soils in Wensu， Hetian and Baicheng counties of the southern Xinjiang were selectThe objective of the present article is to ascertain the mechanism of hyperspectral remote sensing monitoring for soil salinization, which is of great importance for improving the accuracy of hyperspectral remote sensing monitoring. Paddy soils in Wensu， Hetian and Baicheng counties of the southern Xinjiang were selected. Hyperspectral data of soils were obtained. Soil salt content (St) an electrical conductivity of 1∶5 soil-to-water extracts (EC1∶5) were determined. Relationships between St and EC1∶5 were studied. Correlations between hyperspectral indices and St, and EC1∶5 were analyzed. The inversion accuracy of St using hyperspectral technique was compared with that of EC1∶5. Results showed that: significant (p<0.01) relationships were found between St and EC1∶5 for soils in Wensu and Hetian counties, and correlation coefficients were 0.86 and 0.45, respectively; there was no significant relationship between St and EC1∶5 for soils in Baicheng county. Therefore, the correlations between St and EC1∶5 varied with studied sites. St and EC1∶5 were significantly related with spectral reflectance, first derivative reflectance and continuum-removed reflectance, respectively; but correlation coefficients between St and spectral indices were higher than those between EC1∶5 and spectral indices, which was obvious in some sensitive bands for soil salinization such as 660, 35, 1 229, 1 414, 1 721, 1 738, 1 772, 2 309 nm, and so on. Prediction equations of St and EC1∶5 were established using multivariate linear regression, principal component regression and partial least-squares regression methods, respectively. Coefficients of determination, determination coefficients of prediction, and relative analytical errors of these equations were analyzed. Coefficients of determination and relative analytical errors of equations between St and spectral indices were higher than those of equations between EC1∶5 and spectral indices. Therefore, the responses of high spectral information to St were more sensitive than those of high spectral information to EC1∶5. Accuracy of St predicted from high spectral data was higher than that of EC1∶5 estimated from high spectral data. The results of this study can provide a theoretical basis to improve hyperspectral remote sensing monitoring accuracy of soil salinization..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 510 (2014)
Phenology of Forest Vegetation in Northeast of China in Ten Years Using Remote Sensing
HOU Xue-hui, NIU Zheng, and GAO Shuai
Plant phenology is the best indicator of terrestrial ecosystem response to climate change and it becomes a hot issue in the study of global change. The forest in northeast of China plays an important part in global forest ecosystem. In this paper, yearly integrated Normalized Difference Vegetation Index (NDVI) of foresPlant phenology is the best indicator of terrestrial ecosystem response to climate change and it becomes a hot issue in the study of global change. The forest in northeast of China plays an important part in global forest ecosystem. In this paper, yearly integrated Normalized Difference Vegetation Index (NDVI) of forest vegetation in northeast China was calculated based on Spot Vegetation datasets from 2001～2010, which has been filtered using Savtiky—Galoy method. And then, the yearly integrated NDVI profile was fitted using a logistic model. Two key parameters of forest phenology (start of season, SOS; end of season, EOS) were extracted according to the greatest rate of curvature of fitted cumulative NDVI and the length of forest phenology (length of season, LOS) was also analyzed. The main conclusions of this paper are (1) SOS mainly occurs in the 110th～140th day and EOS in 260th and 290th day. SOS displays a marked delayed from south to north while EOS gradually advances. However, the changes of SOS and EOS in ten years are not obvious. (2) Corresponding to the SOS and EOS, LOS of forest in study area mainly occurs in the 120th～160th day; however, it is spatially heterogeneous. LOS of forest in Greater Khingan Mountains is shorter (about 120～140 day) than forests in Xiao Hinggan Ling and Changbai Mountains (about 160 day). The results in this paper are concordant with records of phenology in situ measurements and previous researches in the same area. It indicates that forest phenophases using method in this paper from Spot Vegetation dataset is feasible..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 515 (2014)
Land Salinization Information Extraction Method Based on HSI Hyperspectral and TM Imagery
LI Jin, ZHAO Geng-xing, CHANG Chun-yan, and LIU Hai-teng
This paper chose the typical salinization area in Kenli County of the Yellow River Delta as the study area, selected HJ-1A satellite HSI image at March 15, 2011 and TM image at March 22, 2011 as source of information, and pre-processed these data by image cropping, geometric correction and atmospheric correction. SpectThis paper chose the typical salinization area in Kenli County of the Yellow River Delta as the study area, selected HJ-1A satellite HSI image at March 15, 2011 and TM image at March 22, 2011 as source of information, and pre-processed these data by image cropping, geometric correction and atmospheric correction. Spectral characteristics of main land use types including different degree of salinization lands, water and shoals were analyzed to find distinct bands for information extraction. Land use information extraction model was built by adopting the quantitative and qualitative rules combining the spectral characteristics and the content of soil salinity. Land salinization information was extracted via image classification using decision tree method. The remote sensing image interpretation accuracy was verified by land salinization degree, which was determined through soil salinity chemical analysis of soil sampling points. In addition, classification accuracy between the hyperspectral and multi-spectral images were analyzed and compared. The results showed that the overall image classification accuracy of HSI was 96.43%, Kappa coefficient was 95.59%; while the overall image classification accuracy of TM was 89.17%, Kappa coefficient was 86.74%. Therefore, compared to multi-spectral TM data, the hyperspectral imagery could be more accurate and efficient for land salinization information extraction. Also, the classification map showed that the soil salinity distinction degree of hyperspectral image was higher than that of multi-spectral image. This study explored the land salinization information extraction techniques from hyperspectral imagery, extracted the spatial distribution and area ratio information of different degree of salinization land, and provided decision-making basis for the scientific utilization and management of coastal salinization land resources in the Yellow River Delta..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 520 (2014)
An Improved Classification Approach Based on Spatial and Spectral Features for Hyperspectral Data
LI Na, LI Yong-jie, ZHAO Hui-jie, and CAO Yang
The spatial correlativity and spectral information are not applied synchronously in the classification model of hyperspectral data. To solve this problem, an improved classification approach based on Markov random field (MRF) theory is proposed in our work. The MRF model based on maximum a posteriori is applied to combThe spatial correlativity and spectral information are not applied synchronously in the classification model of hyperspectral data. To solve this problem, an improved classification approach based on Markov random field (MRF) theory is proposed in our work. The MRF model based on maximum a posteriori is applied to combine the spectral and spatial information. The probabilistic support vector machine (PSVM) algorithm using pixels spectral information is applied to improve the estimation accuracy of the class conditional probability (CCP) of the spectral energy function, and the efficient belief propagation (EBP) based on multi-accelerated strategy (such as ordinal propagated message strategy, linearized message-updating strategy, and coarse-to-fine approach) is developed in order to solve the problem of the high calculational complexity and time-consumed in the global energy minimum optimization of MRF model. The true hyperspectral data collected by airborne visible infrared imaging spectrometer (AVIRIS) is applied to estimate the performance of the proposed approach in the agricultural demonstration area, Indiana northwest, USA. The performance of the proposed approach is compared with simulated annealing and iterated conditional model. The results illuminate that the average classification accuracy of our method reachs to 95.78%, and the Kappa coefficient is 93.34%, much higher than that of the result by the traditional MRF classification algorithms, and the computational efficiency is improved more than 3 times compared with the belief propagation algorithm..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 526 (2014)
Study on Identification the Crack Feature of Fresh Jujube Using Hyperspectral Imaging
YU Ke-qiang, ZHAO Yan-ru, LI Xiao-li, ZHANG Shu-juan, and HE Yong
Crack is one of the most important indicators to evaluate the quality of fresh jujube. Crack not only accelerates the decay of fresh jujube, but also diminishes the shelf life and reduces the economic value severely. In this study, the potential of hyperspectral imaging covered the range of 380～1 030 nm was evaluated fCrack is one of the most important indicators to evaluate the quality of fresh jujube. Crack not only accelerates the decay of fresh jujube, but also diminishes the shelf life and reduces the economic value severely. In this study, the potential of hyperspectral imaging covered the range of 380～1 030 nm was evaluated for discrimination crack feature (location and area) of fresh jujube. Regression coefficients of partial least squares regression (PLSR), successive projection analysis (SPA) and principal component analysis (PCA) based full-bands image were adopted to extract sensitive bands of crack of fresh jujube. Then least-squares support vector machine (LS-SVM) discriminant models using the selected sensitive bands for calibration set (132 samples) were established for identification the prediction set (44 samples). ROC curve was used to judge the discriminant models of PLSR-LS-SVM, SPA-LS-SVM and PCA-LS-SVM which are established by sensitive bands of crack of fresh jujube. The results demonstrated that PLSR-LS-SVM model had an optimal effect (area=1, std=0) to discriminate crack feature of fresh jujube. Next, images corresponding to five sensitive bands (467, 544, 639, 673 and 682 nm) selected by PLSR were executed to PCA. Finally, the image of PC4 was employed to identify the location and area of crack feature through imaging processing. The results revealed that hyperspectral imaging technique combined with image processing could achieve the qualitative discrimination and quantitative identification of crack feature of fresh jujube, which provided a theoretical reference and basis for develop instrument of discrimination of crack of jujube in further work..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 532 (2014)
Using Atomic Fluorescence Spectrometry to Study the Spatial Distribution of As and Hg in Orchard Soils
ZHAO Xi-mei, Lv Chun-yan, LIU Qing, and ZHU Xi-cun
Aqua regia digestion, double channels-atomic fluorescence spectrometry method was used to determine the concentrations of As and Hg in orchard soils of Qixia City - the main apple production area of Shandong province. Validate The detection limitation, accuracy and precision of the method were validated, the spatial diAqua regia digestion, double channels-atomic fluorescence spectrometry method was used to determine the concentrations of As and Hg in orchard soils of Qixia City - the main apple production area of Shandong province. Validate The detection limitation, accuracy and precision of the method were validated, the spatial distribution was analyzed, and the characteristics of As and Hg pollution in Qixia orchard soils were assessed. The results showed that the range of As concentration in Qixia soils is between 2.79 and 20.93 mg·kg-1, the average concentration is 10.59 mg·kg-1, the range of Hg concentration in Qixia soil is between 0.01 and 0.79 mg·kg-1， the average concentration is 0.12 mg·kg-1. The variation of As concentration in soils is small, whereas that of Hg concentration is large. Frequency distribution graphics of As and Hg showed that the concentration of As in soils is according with the normal distribution approximately and the concentrations are mostly between 7 and 15 mg·kg-1, the concentration of Hg in soil isnt according with the normal distribution and the concentrations are mostly between 0.03 and 0.21 mg·kg-1. The correlations between the concentrations of As or Hg in soils and the nutrient are not significant and there is no significant correlation even between As and Hg. Based on the environmental technical terms for green food production area, the As concentration in orchard soil of Qixia City is at clean level, but there are 4.76% of sample points with Hg pollution index exceeding 1, and this should be attracted the attention of the administrators..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 538 (2014)
Quantitative Analysis of Alloy Steel Based on Laser Induced Breakdown Spectroscopy with Partial Least Squares Method
CONG Zhi-bo, SUN Lan-xiang, XIN Yong, LI Yang, QI Li-feng, and YANG Zhi-jia
In the present paper both the partial least squares (PLS) method and the calibration curve (CC) method are used to quantitatively analyze the laser induced breakdown spectroscopy data obtained from the standard alloy steel samples. Both the major and trace elements were quantitatively analyzed. By comparing the resultsIn the present paper both the partial least squares (PLS) method and the calibration curve (CC) method are used to quantitatively analyze the laser induced breakdown spectroscopy data obtained from the standard alloy steel samples. Both the major and trace elements were quantitatively analyzed. By comparing the results of two different calibration methods some useful results were obtained: for major elements, the PLS method is better than the CC method in quantitative analysis; more importantly, for the trace elements, the CC method can not give the quantitative results due to the extremely weak characteristic spectral lines, but the PLS method still has a good ability of quantitative analysis. And the regression coefficient of PLS method is compared with the original spectral data with background interference to explain the advantage of the PLS method in the LIBS quantitative analysis. Results proved that the PLS method used in laser induced breakdown spectroscopy is suitable for quantitative analysis of trace elements such as C in the metallurgical industry..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 542 (2014)
Determination of Trace Elements in Rape Honey and Its Corresponding Rape Flower and Stem by ICP-MS
CHEN Hui, WANG Zhi-bin, CHANG Qiao-ying, WANG Wei, FAN Chun-lin, and PANG Guo-fang
The determination of 10 trace elements including Na, Mg, P, K, Ca, Mn, Zn, Rb, Sr and Ba, in rape honey and its corresponding rape flower and stem gathered from nine sampling sites was carried out by inductively coupled plasma mass spectrometry (ICP-MS). The contents of K, P, Ca, Mg and Na were obviously higher than ZnThe determination of 10 trace elements including Na, Mg, P, K, Ca, Mn, Zn, Rb, Sr and Ba, in rape honey and its corresponding rape flower and stem gathered from nine sampling sites was carried out by inductively coupled plasma mass spectrometry (ICP-MS). The contents of K, P, Ca, Mg and Na were obviously higher than Zn, Rb, Mn, Sr and Ba in rape honey, rape flower and rape stem. For the first five elements, K had the highest content, followed by P, Ca, Mg and Na. However, the order of content for latter five elements was not the same in different matrixes. The contents of K, P and Ca were all higher than 1 000 mg·kg-1 in rape flower and rape stem, while the contents of P, Ca, Mn, Zn and Rb in rape flower were slightly higher than in rape stem. It can be concluded that rape flower showed slightly higher concentrating ability for trace elements than rape stem. Based on these results, radar chart was firstly applied to research the relationship of 10 elements in rape honey and its corresponding rape flower and stem. The aim of the present work was to study the possibility of using trace elements contents in rape flower to trace the geographical and botanical origin of honey instead of rape honey. It can be found from the radar charts that the stars of rape honey, rape flower and rape stem were similar to each other. This research not only provides the basic data of trace elements in comparative study of rape honey, but also gives scientific basis for tracing the origin of rape honey according to the trace elements in corresponding rape flower that replaces those of rape honey..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 548 (2014)
Analysis of Mineral Elements in Different Organs at Different Harvesting Times of Schizonepeta tenuifolia on ICP-AES
SHAN Ming-qiu, YU Sheng, YU Li-xia, and DING An-wei
To study the main storage organ of each mineral element in Schizonepeta tenuifolia， and explain its reasonable harvesting time and medicinal parts in view of mineral elements. The mineral elements of Schizonepeta tenuifolia in different organs at different harvesting times were determined by ICP-AES technique. The mineTo study the main storage organ of each mineral element in Schizonepeta tenuifolia， and explain its reasonable harvesting time and medicinal parts in view of mineral elements. The mineral elements of Schizonepeta tenuifolia in different organs at different harvesting times were determined by ICP-AES technique. The mineral elements， K， Ca， Na， P， Mg， Mn， Zn， Cu， Fe， Mo， were determined in the study. The results showed that at different harvesting times， (1) the contents of K， P， Cu in fringe and the contents of Mg， Ca， Na， Fe， Mn， Zn in leaf were highest among different organs. (2) among the macroelements， the contents of K and Ca were highest while the content of Na was lowest； among the microelements， the content of Fe was highest while the content of Mo was lowest. (3) in item， the proportion of K∶P was highest while the proportion of Zn∶Cu was lowest； in fringe， the proportions of Ca∶Mg and Fe∶Mn were lowest. (4) within the harvest period， variations of the mineral elements were not obvious. Conclusions: In the stem of Schizonepeta tenuifolia， the contents of every mineral elements were lower than other organs， including leaves and spikes. Considering the mineral elements， the correlations of harvesting time and content change were not remarkable..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 553 (2014)
High Accuracy Sample Positioning System for Hard X-Ray Microprobe
ZHANG Ji-chao, LIANG Dong-xu, HE Yan, LI Ai-guo, and YU Xiao-han
A novel sample offline positioning system was developed for hard X-ray micro-focus beamline (BL15U1) at Shanghai Synchrotron Radiation Facility (SSRF). The positioning system is composed of three parts: off-line sample microscope system, on-line sample experiment system, and high-precision positioning sample holder. ItA novel sample offline positioning system was developed for hard X-ray micro-focus beamline (BL15U1) at Shanghai Synchrotron Radiation Facility (SSRF). The positioning system is composed of three parts: off-line sample microscope system, on-line sample experiment system, and high-precision positioning sample holder. It makes a potent combination of the on-line X-ray fluorescence imaging and the off-line microscopic examination in three steps: compiling of control program, positioning of sample holder, and conversion of the two coordinates. It’s the first time in the domestic synchrotron radiation facilities to achieve sample offline positioning in micron scale. The system helps the researchers find the object of study in micro zone quickly and accurately, when they study the micro characteristics of materials using synchrotron radiation micro X-ray beam. The gold mesh was used as an object of study. By comparing the differences of coordinates of gold mesh nodes between pictures from offline microscope and pictures from X-ray fluorescence mapping, the accuracy of the offline positioning system was verified. The results showed that the average errors of X-axis and Z-axis were 1.3 and 2.5 μm respectively, using the positioning method. It was demonstrated that the sample offline positioning system not only is suitable for these applications with high efficiency, but also supply hard X-ray micro-focus beamline with the technical preparations of sample automatic focusing method..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 557 (2014)
Application of the Racial Algorithm in Energy Dispersive X-Ray Fluorescence Overlapped Spectrum Analysis
ZENG Guo-qiang, LUO Yao-yao, GE Liang-quan, ZHANG Qing-xian, GU Yi, and CHENG Feng
In the energy dispersive X-ray fluorescence spectrum analysis, scintillation detector such as NaI (Tl) detector usually has a low energy resolution at around 8%. The low energy resolution causes problems in spectral data analysis especially in the high background and low counts condition, it is very limited to strip thIn the energy dispersive X-ray fluorescence spectrum analysis, scintillation detector such as NaI (Tl) detector usually has a low energy resolution at around 8%. The low energy resolution causes problems in spectral data analysis especially in the high background and low counts condition, it is very limited to strip the overlapped spectrum, and the more overlapping the peaks are, the more difficult to peel the peaks, and the qualitative and quantitative analysis cant be carried out because we cant recognize the peak address and peak area. Based on genetic algorithm and immune algorithm, we build a new racial algorithm which uses the Euclidean distance as the judgment of evolution, the maximum relative error as the iterative criterion to be put into overlapped spectrum analysis, then we use the Gaussian function to simulate different overlapping degrees of the spectrum, and the racial algorithm is used in overlapped peak separation and full spectrum simulation, the peak address deviation is in ± 3 channels, the peak area deviation is no more than 5%, and it is proven that this method has a good effect in energy dispersive X-ray fluorescence overlapped spectrum analysis..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 562 (2014)
The Radial Velocity Measurement Accuracy of Different Spectral Type Low Resolution Stellar Spectra at Different Signal-to-Noise Ratio
WANG Feng-fei, LUO A-li, and ZHAO Yong-heng
The radial velocity of the star is very important for the study of the dynamics structure and chemistry evolution of the Milky Way, is also an useful tool for looking for variable or special objects. In the present work, we focus on calculating the radial velocity of different spectral types of low-resolution stellar sThe radial velocity of the star is very important for the study of the dynamics structure and chemistry evolution of the Milky Way, is also an useful tool for looking for variable or special objects. In the present work, we focus on calculating the radial velocity of different spectral types of low-resolution stellar spectra by adopting a template matching method, so as to provide effective and reliable reference to the different aspects of scientific research. We choose high signal-to-noise ratio (SNR) spectra of different spectral type stellar from the Sloan Digital Sky Survey (SDSS), and add different noise to simulate the stellar spectra with different SNR. Then we obtain the radial velocity measurement accuracy of different spectral type stellar spectra at different SNR by employing a template matching method. Meanwhile, the radial velocity measurement accuracy of white dwarf stars is analyzed as well. We concluded that the accuracy of radial velocity measurements of early-type stars is much higher than late-type ones. For example, the 1-sigma standard error of radial velocity measurements of A-type stars is 5~8 times as large as K-type and M-type stars. We discuss the reason and suggest that the very narrow lines of late-type stars ensure the accuracy of measurement of radial velocities, while the early-type stars with very wide Balmer lines, such as A-type stars, become sensitive to noise and obtain low accuracy of radial velocities. For the spectra of white dwarfs stars, the standard error of radial velocity measurement could be over 50 km·s-1 because of their extremely wide Balmer lines. The above conclusion will provide a good reference for stellar scientific study..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 565 (2014)
Research of Dual-Photoelastic-Modulator-Based Beat Frequency Modulation and Fourier-Bessel Transform Imaging Spectrometer
WANG Zhi-bin, ZHANG Rui, WANG Yao-li, HUANG Yan-fei, CHEN You-hua, WANG Li-fu, and YANG Qiang
As the existing photoelastic-modulator(PEM) modulating frequency in the tens of kHz to hundreds of kHz between, leading to frequency of modulated interference signal is higher, so ordinary array detector cannot effectively caprure interference signal. A new beat frequency modulation method based on dual-photoelastic-moAs the existing photoelastic-modulator(PEM) modulating frequency in the tens of kHz to hundreds of kHz between, leading to frequency of modulated interference signal is higher, so ordinary array detector cannot effectively caprure interference signal. A new beat frequency modulation method based on dual-photoelastic-modulator (Dual-PEM) and Fourier-Bessel transform is proposed as an key component of dual-photoelastic-modulator-based imaging spectrometer (Dual-PEM-IS) combined with charge coupled device (CCD). The dual-PEM are operated as an electro-optic circular retardance modulator, Operating the PEMs at slightly different resonant frequencies ω1 and ω2 respectively, generates a differential signal at a much lower heterodyne frequency that modulates the incident light. This method not only retains the advantages of the existing PEM, but also the frequency of modulated photocurrent decreased by 2~3 orders of magnitude (10~500 Hz) and can be detected by common array detector, and the incident light spectra can be obtained by Fourier-Bessel transform of low frequency component in the modulated signal. The method makes the PEM has the dual capability of imaging and spectral measurement. The basic principle is introduced, the basic equations is derived, and the feasibility is verified through the corresponding numerical simulation and experiment. This method has potential applications in imaging spectrometer technology， and analysis of the effect of deviation of the optical path difference. This work provides the necessary theoretical basis for remote sensing of new Dual-PEM-IS and for engineering implementation of spectra inversion..
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 569 (2014)
[in Chinese]
Spectroscopy and Spectral Analysis
- Publication Date: Jan. 01, 1900
- Vol. 34, Issue 2, 1 (2014)
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