15 March 2022, Volume 34 Issue 1
    

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    Papers by young scholars at the２１th National Conference on light scattering
  • Research on Raman Spectrum Classification Based on  Convolution Neural Network Feature Extraction
    ZUO Jiaqian, WANG Yukai, WANG Hongqiu, GENG Lin
    Chinese Journal of Light Scattering. 2022, 34(1): 1-5. https://doi.org/10.13883/j.issn1004-5929.202201001
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Raman spectroscopy has been widely used in chemical industry, security,anti drug and other industries and research fields, but the traditional Raman spectroscopy analysis technology relies on the spectral database, through the spectral feature extraction for identification. Feature extraction is the key step of Raman recognition. Principal component analysis, factor analysis and other methods are usually used for feature extraction, and then KNN, SVM and random forest methods are used for qualitative identification of spectral features. When there is no undetermined substance in Raman database, it is easy to cause the wrong classification of the substance to be detected. In order to solve this problem, a method based on convolution neural network is proposed to identify the lack of substance spectrum in database. In the process of the experiment, we use nine categories, more than 200 kinds of psychotropic drugs Raman spectrum as the test object, through the construction of convolution neural network automatic feature extraction, and use softmax classifier to analyze more than 200 kinds of substances according to nine categories, such as amphetamine, cathinone, cannabinoids and so on. Compared with the traditional machine learning methods such as  k nearest  neighbor and support vector machine, the accuracy of model recognition based on convolution neural network is significantly improved. This method can provide a new recognition method for Raman spectrum database.
  • Raman Spectroscopy of Boron Carbon Nitride Films Prepared  by RF Magnetron Sputtering Method
    LIU Caiyun, LI Yujing, GAO Wei, YIN Hong
    Chinese Journal of Light Scattering. 2022, 34(1): 6-9. https://doi.org/10.13883/j.issn1004-5929.202201002
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    Boron carbonitride (BCN) ternary compound films have adjustable composition ratio of atoms, and can show the corresponding material properties, so has broad application prospects in the field of mechanics, thermology, optic, electronics and so on. In this work, we report the synthesis of BCN films with various compositions on  p  type Si (100) substrates via radio frequency (rf) magnetron sputtering. As N 2 flow increases, nitrogen atoms can be incorporated into the turbostratic structure with a concentration of ~ 14 at.%. In addition to D and G bands, the N=N stretching morder to investigate the changes of structure and properties of BCN ternary system, Raman spectroscopy was used to systematically study the preparation of BCN ternary system with different nitrogen flow rates. The results show that, ode in Raman spectra becomes visible due to the excess of nitrogen incorporation.In addition, the disorder of the sample also led to an overall change in the Raman spectrum. 
  • The Raman Spectroscopy Study of γ-Cu2 (OH)3 Cl under  Atmospheric and High Pressure
    LUO Yaxiao, ZHANG Jian, LI Yanwei
    Chinese Journal of Light Scattering. 2022, 34(1): 10-14. https://doi.org/10.13883/j.issn1004-5929.202201003
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    γ-Cu2 (OH)3 Cl is one of the isomers of copper hydroxychloride, which exists widely in nature  It can not only be used as biological copper nutrient additives, but also has exotic magnetic properties Clinoatacamite (γ-Cu2 (OH)3 Cl) was prepared via a hydrothermal synthesis strategy  The Raman scattering spectroscopy test was first carried out under atmospheric pressure, and the frequencies were divided into low frequency region and medium frequency region, respectively  The spectral bands were attributable and divided in detail  The lattice vibrations and crystal structure evolution behavior of γ-Cu2 (OH)3 Cl under high pressure were studied by using in situ high pressure Raman scattering spectroscopy technique, and the maximum pressure reached 17.8 GPa  The changes of Raman vibration modes with pressure were studied, and the red shift phenomenon is analyzed and explained  The results of this study may provide fundamental spectroscopic theory and basic data in the calibration of copper nutrient additives
  • Qualitative Analysisfor Raman Mixed Spectra from the Ibuprofen  Capsules Based on DSCS-ICA
    NING Ronghua, SU Hui, ZHOU Dandan, YAO Zhixiang
    Chinese Journal of Light Scattering. 2022, 34(1): 15-21. https://doi.org/10.13883/j.issn1004-5929.202201004
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    Raman spectroscopy has the advantages of non contact, non destructive, low cost and high throughput, and has been paid more attention to in the analysis of multi component systems. Independent component analysis (ICA) is not only a multivariate statistical method, but also a blind separation method. It can solve the estimated source spectra of each component in the system only by measuring the mixed spectra without prior knowledge. However, when there is significant overlap between the source spectra, ICA separation results are not reliable. In this paper, an improved ICA qualitative analysis algorithm is proposed, which is based on the derivation of the spectrum of the system, ICA separation, and then separation after removing components step by step (Derivation, Separation,Culling and Separation, DSCS-ICA),the approximate estimation of the source spectrum is obtained by separation, and the qualitative analysis of the system is realized, which solves the problem of poor separation performance of the existing ICA algorithm caused by spectral overlap.According to the formula of ibuprofen capsule, 12 samples of ibuprofen capsule were prepared with different proportions of five components, including ibuprofen, stearic acid, polyvinylpyrrolidone K30, starch and sucrose, and their Raman spectral data were collected. The components (IC3 ) were solved by DSCS-ICA method, and the IC3 was compared with the source spectrum, and the correlation coefficient r was used to judge the consistency between IC3and the source spectrum. The results show that, compared with FastICA, the effect of DSCS-ICA is significantly improved, and the correlation coefficient  r  of  IC3and the source spectrum is above 0.99, which shows that the results have good reliability and correspondence. This case can provide reference for the reverse study of drug prescription ingredients, and can be applied to the qualitative analysis of other multicomponent systems. 
  • Quantitative Study on Microstructure of (CaO-SiO2)-xAl2O3  Ternary Glass by Raman Spectroscopy
    Chinese Journal of Light Scattering. 2022, 34(1): 22-29. https://doi.org/10.13883/j.issn1004-5929.202201005
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    A series of (CaO-SiO2)-xAl2O3 (x=0, 6, 12, 18, 24, 30) glasses were successfully prepared in a pneumatic suspension device, and their structures were qualitatively and quantitatively studied by Raman spectroscopy, quantum chemistry ab initio calculation and  27 Al MAS-NMR. It shows that when the basicity R (CaO/SiO2)=1 , Al mainly participates in the network formation in the form of ［ Ⅳ AlO4］ by x≤18 and reaches the maximum when x=18. At the same time, the existence of ［Ⅴ AlO5］ and ［Ⅵ AlO6］ is also observed; When x>18, the relative content of ［Ⅳ AlO4］ decreased, while ［Ⅴ AlO5］ and ［Ⅵ AlO6］ increased. The results of Raman fine resolution spectra show that the addition of Al greatly increases the complexity and disorder of the structure, which is manifested by the irregular change of the content of fine structure Qijklm, but has little effect on the content of primary structure Qi which mainly exists in the form of Q2.
  • Simultaneous Detection of Sildenafil and Tadalafil in  Healthcare Products by Raman Spectroscopy
    SI Xingyu, CHEN Zhi, ZHOU Qianyu, CHEN Zhuo, WANG Hongqiu
    Chinese Journal of Light Scattering. 2022, 34(1): 30-36. https://doi.org/10.13883/j.issn1004-5929.202201006
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    Sildenafil and tadalafil are often illegally added in healthcare products, and large numbers of related criminal cases were reported in recent years. Therefore, rapid detection of sildenafil or tadalafil is of great significance for the crackdown on related crimes. Compared with laboratory methods, Raman spectroscopy is a simple and low cost technique. These years, it has been increasingly applied in rapid screening of illegally added drugs in healthcare products. In this manuscript, a method capable of simultaneously detecting sildenafil and tadalafil in healthcare products was established based on surface enhanced Raman spectroscopy. Using a portable Raman spectrometer, the detection limit reached 5 mg/kg for sildenafil, and 10 mg/kg for tadalafil. This method could detect many types of healthcare products including capsules and tablets within only 10 minutes. The methods developed could be employed by market supervision departments and public security departments, and have broad application prospects in the field of food safety analysis.
  • The detection of inorganic compounds using Echelle-Mirror  Spatial Heterodyne Raman Spectroscopy
    QIU Jun, CHENG Jing, PENG Rongchao, LI Zezhen, DONG Li, XU Jiayue, YAN Yanli, LIN Lin, ZHANG Huaiceng, JIRI Galantu, LI Xiaotian, QI Xiangdong
    Chinese Journal of Light Scattering. 2022, 34(1): 36-40. https://doi.org/10.13883/j.issn1004-5929.202201007
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    In thispaper, an Echelle-Mirror Spatial Heterodyne Raman Spectrometer (Echelle-Mirror Spatial Heterodyne Raman Spectroscopy, EMSHRS) breadboard was designed and built using four diffraction order of an echelle. The calibration procedure is performed using a standard lamp to estimate the spectral resolution (1.033 cm-1) and spectral range of one diffraction order (1058 cm-1). The Raman spectrum of p n pentane, n octane and isopropyl alcohol are discussed, which demonstrate that the EMSHRS has great prospects for fast and broadband detection in inorganic compounds.
  • Preparation of Raman Active Polymer with Encoding of Triple  Bonded Raman Intensity and Cell Imaging
    ZHU Wei, SHEN Aiguo, Hu Jiming
    Chinese Journal of Light Scattering. 2022, 34(1): 40-46.
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    Triple bond based Raman scattering tags have attracted extensive researchers’ attention for biological multivariate labeling. However, there are still difficult to break through the “color limit”, the synthesis of signal molecules based on Raman shifts of triple bond is difficult, and the signal noise ratio of small Raman molecules is poor. In this paper, small molecular monomers containing strong triple bond Raman scatters were rationally tailored and polymerized at the nanoscale level, which could enhance imaging contrast with smaller but brighter optical nanotags with artificial ‘fingerprint’ output. In particular, a class of triple bond rich polymer nanoparticles (NPs) has been engineered by regulating the relative dosages of three chemically different triple bond monomers in co polymerization, and the suggested bonding can achieve 15 spectrally distinguishable triple bond combinations. The accurate construction of structured nano molecular aggregates will become a universal method for small size, high sensitivity and high throughput biological imaging tags for multi color imaging. 
  • Investigating the Kinetic Rate Constant of SO2 Oxidation with Levitated  NaCl Single Droplet Using Optical Tweezer Stimulated Raman Spectroscopy
    CHEN Zhe, LIU Pai, PANG Shufeng, ZHANG Yunhong
    Chinese Journal of Light Scattering. 2022, 34(1): 46-52. https://doi.org/10.13883/j.issn1004-5929.202201009
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    Sulfate is an important secondary inorganic component of haze particles, its formation mechanism, however, is still not completely clear. Besides, current air quality models often underestimate the sulfate formation amount, and cannot reproduce the field observation results successfully. Hence, it is essential to give insight into the atmospheric sulfate formation processes, which contributes to the understanding of haze formation mechanism and precise control of haze pollution. In this study, the non catalytic oxidation process of SO2 with NaCl droplet was observed by optical tweezer stimulated Raman spectroscopy. The nanoscale change of droplet radius during the reaction process can be accurately measured, so that the real time reaction process can be in situ observed. According to the measured reaction rate, the pseudo first order rate constant k was calculated, and the effects of relative humidity and SO2 concentration on the reaction were also investigated. Results showed that the change of droplet ionic strength caused by varied relative humidity significantly affected the k value. When the humidity increased from ~60% to ~90%, the k value decreased by an order of magnitude. As to the effect of SO2 concentration, increased SO2 concentration decreased the pH of the droplet, leading to a slight decrease in the k value. Based on the further discussion of the reaction mechanism, we found both bulk phase reaction and interface reaction may contribute to the non catalytic oxidation of SO2 with NaCl droplet.
  • Heterogeneous Reaction of Atmospheric SO2/NO2Using Micro FTIR Spectroscopy
    FENG Yu, LIU Pai, PANG Shufeng, ZHANG Yunhong
    Chinese Journal of Light Scattering. 2022, 34(1): 53-59. https://doi.org/10.13883/j.issn1004-5929.202201010
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    Sulfate is a major component of the urban PM2.5 in China. The current air quality models consistently underestimate the particulate sulfate formation during haze episodes, indicating that our understanding on the mechanism of atmospheric SO2 conversion remains incomplete. Recently, the synergistic oxidation of SO2 and NO2 within aerosol microdroplets has been recognized as a key additional pathway for SO2 atmospheric conversion. However, the influence of ambient conditions (such as molar ratio of reactant gases and relative humidity) on the reaction kinetics remains understudied. Here we adopt micro-Fourier transform infrared (micro-FTIR) spectroscopy to measure the time-evolution of SO42- and NO3- concentration within a single MgCl2 microdroplet, under various SO2/NO2 molar ratio. We observed that: The single droplet of MgCl2 reacts with SO2/NO2 to form SO42- and NO3-，and that the formation rate of SO42- is the fastest when the molar ratio of SO2/NO2 is 1:5. Our research will provide reliable kinetic parameters for air-quality model, which will in turn aid the policy makers to device informed PM2.5 containment strategies.
  • Thin-layer TMDC Sample Detection Based on Reflectance  Hyperspectral Imaging
    HU Xiangmin, LIU Dameng
    Chinese Journal of Light Scattering. 2022, 34(1): 60-65. https://doi.org/10.13883/j.issn1004-5929.202201011
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    Two-dimensional transition metal sulfides (TMDCs) are widely used in solar cells, photocatalysis, sensors, flexible electronic devices and other fields due to their unique exciton effect and material properties. The layer-number has a significant effect on their properties, thus rapid and automatic detection technology of TMDC samples with required layer-number is urgently required for their application expanding from laboratories to semiconductor manufacturing industries. In this paper, a thin-layer TMDC sample automatic detection technology was proposed, combining the hyperspectral imaging method and the image processing algorithm. The optical contrast of TMDC samples with different layer-numbers was systematically studied using a self-built reflection hyperspectral imaging system. The differential reflection mechanism of the optical contrast was elucidated, and a reliable layer-number determination method was proposed. Additionally, an image processing algorithm was designed to seek out TMDC samples with determined layer-number from the microscopic images. This method is universal and practical which can realize large-scale automatic sample detection when combining with auto-focus scanning control. It also provides new inspiration for detection of other surface targets at microscopic view.
  • Effect of Optical Clearing Agents on Optical Coherence  Tomography of Biological Tissue
    WANG Kaicong, FANG Wenhui, ZOU Peng, LU Dongxiao, LI Jinhua
    Chinese Journal of Light Scattering. 2022, 34(1): 66-72. https://doi.org/10.13883/j.issn1004-5929.202201012
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    Tissue optical clearing provides a good solution to some problems, such as biological tissue has high scattering and turbidity, which seriously affects the contrast and resolution of biological tissue imaging. Ex vivo porcine skin surfaces are coated with OCA such as polyethylene glycol, glycerol and propanediol in different concentrations. Use OCT to dynamically monitor it, and effectively extract the measured signal as it changes with the measured depth during penetration. The results show that the optical transparency technology can increase the imaging depth of OCT. However, for different OCA, the effect of different depth is different. This study provides a valuable data reference for the optimal choice of OCA concentration and time for different depths. This study gives us a further understanding of the mechanism of OCA and will be helpful in guiding the use of OCA in medicine.
  • Preparation and application of stable gold-silver and gold-copper alloy nanoparticles
    LI Tian, LIU Hongmei, QIN Youjian, TIAN Honghao, ZHANG Xinping
    Chinese Journal of Light Scattering. 2022, 34(1): 73-77. https://doi.org/10.13883/j.issn1004-5929.202201013
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    The nanostructures of precious metals such as gold, silver and copper all have surface plasmon resonance effects, which have important applications in the fields of surface enhanced Raman scattering (SERS) and photocatalysis. Alloy nanoparticles are expected to have the advantages of multiple metals, giving metal nanoparticles more excellent qualities. In this paper, we have successfully synthesized Au1Ag1 and Au1Cu1 alloy nanoparticles with the diameter of 1~5 nm by improving the "Brust" method. The prepared alloy nanoparticles have good stability in the air and good solubility in organic solvents. We then assembled Au1Ag1 and Au1Cu1 alloy SERS substrates by a solution processible method, which shows good SERS performance for 532 nm and 785 nm excitation lasers, respectively. Under the same conditions, the Raman signal intensity of the Au1Ag1 substrates to the R6G probe molecule is increased by 2~4 times than that of the Au substrates, showing good SERS activity. The Au1Cu1 alloy substrates exhibit stronger photocatalytic activity than the Au1Ag1 alloy and Au substrates, and shows potential applications value in the field of photocatalysis.
  • Thermal Phase Transformation and Quantitative Analysis of  Cryolite Molten Salt
    ZHANG Fu, YOU Jinglin, WANG Jian, WANG Min, GONG Xiaoye, TANG Xiaohui, LU Liming
    Chinese Journal of Light Scattering. 2022, 34(1): 78-84. https://doi.org/10.13883/j.issn1004-5929.202201014
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    In this work, cryolite crystals with a molecular ratio of CR=3 in the NaF-AlF3 binary system were prepared, and a series of aluminum-fluorine cluster structure models were constructed. The micro-confocal Raman spectroscopy detection technology was combined with first-principle theoretical calculations. The author observed and studied the temperature-induced phase transition process of cryolite, and analyzed the Raman characteristic peak positions of anionic clusters such as AlF4-(622-628 cm-1), AlF52-(555-560 cm-1), AlF63-(510-515 cm-1). As for the cryolite molten salt system, by correcting the scattering cross section and splitting the peak of the molten salt experimental Raman spectrum, quantitatively analyzed the microstructure of cryolite molten salt. In the cryolite molten salt, the various anionic clusters have molar percentages of AlF4-(2.7%), AlF52-(25.8%), AlF63-(40.4%), F-(31.3%).
    • Overview
  • Research Progress and Application of Raman Spectroscopy on the Analysis of Nuclear Fuel
    PENG Manshu, FENG Weiwei, CAO Qi, HU Yin, CHEN Yunming, WANG Dingna
    Chinese Journal of Light Scattering. 2022, 34(1): 85-94. https://doi.org/10.13883/j.issn1004-5929.202201015
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    It is one of the bases for the reliable prediction of the fuel performance in nuclear power reactors to analyze and characterize the physical and chemical properties of nuclear fuels before and after irradiation. Raman spectroscopy can obtain the information of the molecular morphology and phase structure changes of materials by the analysis of molecular vibration modes. It has been widely used in the characterization of nuclear fuels due to its excellent qualitative and quantitative analysis ability with the advantage of microscale, non-invasion, in-situ and high efficiency. In this paper, the basic principles of several Raman spectroscopy techniques are briefly summarized. The application and research progress of Raman spectroscopy on nuclear fuel analysis are summarized in the corrosion analysis, radiation damage analysis, temperature monitoring and the encapsulation technology of high radioactivity samples. The limitations of Raman spectroscopy techniques are introduced, and in view of nuclear fuel analysis, the future research and application of Raman spectroscopy are prospected from the aspects of coupled techniques and database establishment.
    • Other Optical Spectroscopic Techniques and Applications
  • Spectrometric Analysis of Crystalline Efflorescence in  one Han Dynasity Eaves Tile
    WU Na, WANG Keqing, YAN Defu, LEI Lei
    Chinese Journal of Light Scattering. 2022, 34(1): 95-95. https://doi.org/10.13883/j.issn1004-5929.202201016
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    Crystalline efflorescence was found on some eaves tiles collection in National Museum of China. In order to recognize the composition of the salts, some sample was collected from one piece of eaves tile. 3D video microscope and scanning electron microscopy were applied to observe its morphology, the crystalline salt included yellow-white powder and white fibrous crystals. Raman spectroscopy, infrared spectroscopy and X-ray diffraction were used to identify the two kinds of salts. According to the mutual confirmation of different spectral analysis results, the main composition of yellow-white powder was calcium carbonate, while the main composition of fibrous crystals was thecotrichite. Thecotrichite is an efflorescent salt occurring on surfaces of porous calcareous objects stored in wooden cabinets. Those wooden cabinets are easily emitting amounts of acetic acid vapor. Therefore, it is recommended that the eaves tile be removed from the wooden cabinet, desalinated, and stored in an acid-free environment. The spectroscopic method can provide technical support for identification of ancient pottery crystal salt composition. The results provide scientific data guidance for the establishment of the conservation and rehabilitation programme.
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