30 September 2020, Volume 32 Issue 3
    

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  • Photoacoustic imaging
    JIANG Wen-ping1，WU Qi-xin2，MIN Jun，DAI Cui-xia*
    The Journal of Light Scattering. 2020, 32(3): 195-201. https://doi.org/10.13883/j.issn1004-5929.202003001
    Abstract ( ) Download PDF ( ) Knowledge map Save
    Photoacoustic imaging is a non-invasive 3D imaging technique which has been developing rapidly in recent years. It combines the high contrast characteristics of pure optical imaging with the high penetration depth characteristics of pure ultrasonic imaging. It provides an important means to study characteristics of biological tissues. In this paper, the principle of photoacoustic imaging technology and method and situation of photoacoustic imaging in biomedical application .
  • Aging Phase Diagnosis of Oil Paper Insulation Based on Raman Spectral Similarity Ratio
    The Journal of Light Scattering. 2020, 32(3): 202-209. https://doi.org/10.13883/j.issn1004-5929.202003002
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    The stable operation of oil-paper insulation power equipment is an important link to ensure the reliability of the power system. However, existing methods have difficulty in diagnosing on the oil-paper insulation ageing. Besides, most of them are suitable for laboratory analysis with a lack of fast and effective diagnose method in actual application. Experimental study about accelerating aging has been done, which is based on IEEE recommended law, to acquire the samples about aging oil- paper paper in different degree. Three types of central Raman spectra , including early, middle and late, were constructed. By using Euclidean distance, chi-square distance and jensen-sinon divergence, respectively, three spectral similarity discrimination methods were used to established a point-wise comparison based Raman spectral diagnosis method for oil-paper insulation aging. Diagnostic analysis of 10 test samples obtained in the experiment, and the diagnostic maximum accuracy was up to 100% (10/10).
  • Discrimination of Pollen by Surface Enhanced Raman Spectroscopy
    FU Zhiqiu1, LIU Gang1*, AN Ran1, OU Quan-hong1, YANG Weimei1, LI Jianmei1, SHI Youming2
    The Journal of Light Scattering. 2020, 32(3): 210-216. https://doi.org/10.13883/j.issn1004-5929.202003003
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    In order to distinguish different kinds of pollen, Pinus massoniana Lamb pollen and seven kinds of bee pollen (camellia pollen, lotus pollen, rose pollen, buckwheat pollen, schisandra pollen, motherwort pollen and rape pollen) were observed by scanning electron microscope, and were characterized by surface enhanced Raman spectroscopy. The results showed that the morphological differences among pollens were small, and it was difficult to distinguish different kinds of pollens by scanning electron microscopy, while SERS could identify different kinds of pollen simply and quickly. Seven kinds of bee pollen had significant difference in the range of 1800-400 cm-1. Compared with bee pollens, Pinus massoniana Lamb pollen had more clearly discernible Raman peaks, and its main characteristic peaks appear near 1701、1657、1572、1522、1397、1293、1208、810 and 565 cm-1.
  • Study on SERS substrate properties of Au@PS arrays
    PEI Junyan1, XU Zongwei2, WANG Gang1, ZHANG Yu1
    The Journal of Light Scattering. 2020, 32(3): 217-223. https://doi.org/10.13883/j.issn1004-5929.202003004
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    Surface-enhanced Raman scattering (SERS) is an efficient method for substance detection. Unlike conventional Raman scattering, whose signal is too weak to be detected, SERS has been widely used in many applications due to its superior merits of high sensitivity. Priori knowledge of SERS substrate characteristics contributes to improve the performance of the prepared SERS substrate. In this paper, SERS substrate on the basis of Au@PS array was prepared using lon sputtering coating. The size and clearance of the sphere were controlled by adjusting the coating thickness. Performance and surface features of a variety of SERS substrates with different coating thickness were studied. SEM results indicate that gold particles on the outside surface membrane layer are obviously visible when the coating thickness is 50 nm. Subsequently, Raman characteristics of the prepared substrate were valued by using Rhodamine 6G . Results show that the SERS substrate with a coating thickness of 50 nm has the strongest enhancement effect. Simulations were also carried out to get a better knowledge of the electromagnetic field distribution within the prepared SERS substrate. Results of FDTD simulation show that the electromagnetic of the clearance and field near the gold particles is strong. And meanwhile, the intensity of the electromagnetic field is the strongest when the coating thickness is equal to 50 nm, which is in agreement with the experimental results.
  • Detection of 5-Fluorouracil by Surface Enhanced Raman Spectroscopy
    Zhou Guoliang 1,2, Huang Guangyao 1,2, Li Pan1, Wang Hongzhi 1,3*, Yang Liangbao 1*
    The Journal of Light Scattering. 2020, 32(3): 224-229. https://doi.org/10.13883/j.issn1004-5929.202003005
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    In this paper, Surface Enhanced Raman Spectroscopy (SERS) was used to realize the sensitive detection of 5-fluorouracil (5-FU). Silver nanoparticles (AgNPs) with different diameters were prepared by seed growth method. Crystal Violet (CV) was used as a probe molecule to evaluate the enhancement ability of the SERS substrate. The optimized AgNPs were used as SERS substrates and the standard solutions of 5-FU with different concentrations were detected by portable Raman spectroscopy. Finally, 5-FU spiked in human serum was determined after the pretreatment of serum. Protein was removed by organic precipitation to reduce detection interference and the detection limit of 5-FU in serum was 3.125 g/mL.
  • Influences by substituents on the geometrical structure, infrared and raman vibration frequency and electronic spectrum for meso-tetraphenylporphyrin: A theoretical study
    ZHANG Jian* Li Xiu
    The Journal of Light Scattering. 2020, 32(3): 230-236. https://doi.org/10.13883/j.issn1004-5929.202003006
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    The influences on the geometrical structure, vibration frequency and electronic spectrum of substituents attached to the phenyl group on the meso-tetraphenylporphyrin (H2TPP) were performed by the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. It was found that, except for slight deformation in derivative 8, there is little change in the porphyrin ring center structure, and the main influence position lies on the Cm atom. For the strong electron-donating group methoxyimino of derivative 8, we can find that the HOMO and LUMO energy levels significantly increased, and HOMO-LUMO Gap value reduced to 4.49eV. This means the strong Q band corresponds to the movement of electrons from the substituent to the porphyrin ring center, and produces a persistent absorption spectrum from UV to IR. Hence the derivative is possible to become efficient porphyrin photosensitizers in DSSCs.
  • Quantitative Analysis for Non-aromatic Hydrocarbon in the Feedstock of an Adsorption Tower in a P-Xylene Unit Based on Raman Spectroscopy
    JIANG Piaoyi, DAI Liankui
    The Journal of Light Scattering. 2020, 32(3): 237-244. https://doi.org/10.13883/j.issn1004-5929.202003007
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    The feedstock in an adsorption tower in a p-xylene unit is mainly composed of ethylbenzene(EB), p-xylene(PX), m-xylene(MX), o-xylene(OX) and other non-aromatic hydrocarbon components (denoted as NA). The content of NA is about 3~10% of feedstock, which will directly affect the adsorption tower operation and the purity of PX product, so it needs to be detected online quickly. However, NA is a mixture of different alkanes, whose composition is unknown, so it is difficult to analyze NA in the feedstock. Therefore, this paper proposed a novel method based on two spectral decomposition algorithms for two Raman spectral regions. According to the difference of Raman spectra between aromatic components and NA, two characteristic regions are chosen. NA spectral components can be neglected in the region 650 ~ 900 cm-1, so a direct decomposition algorithm is applied to get their corresponding peak areas based on spectra of pure components EB, PX, MX and OX. In the region 1350 ~ 1550 cm-1, another spectral decomposition algorithm based on Lorentzian function is adopted to obtain the spectral peak of NA which is fitted by several Lorentz peaks, then the corresponding peak area is calculated. Finally, the linear models between peak areas and concentrations of each component are built with all training samples. The experimental results show that the standard prediction error for NA is 0.242 %, and the correlation coefficient reaches 0.993. This method can provide more precision than PLS and direct spectral decomposition algorithms, so the new method can be widely applied, especially for the mixture composed of several known components and some unknown substances.
  • Research on Surface Defect Detection Method of Glass Wafer Based on Light Scattering Theory
    Tu Zhengqian1*, Dong Lichao3, Zhao Dongfeng3, Feng Di2, Wang Shenze1
    The Journal of Light Scattering. 2020, 32(3): 245-250. https://doi.org/10.13883/j.issn1004-5929.202003008
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    This paper analyzes the scattered light intensity of three types of defects commonly encountered in glass wafer processing: particle defects, bubble defects, and triangular scratches. It is found that different defect structures have different scattered light in space. The strong distribution feature can establish the correspondence between the defect structure and the spatial distribution of scattered light intensity. At the same time, for the micron-scale defects on the wafer surface in the production line, the scattered light intensity of different size particle defects is calculated, and the micron-scale defect size is obtained. Therefore, a non-imaging defect detection method is proposed: detecting the scattered light intensity value and spatial distribution of the acquired defect, determining the defect structure by using the spatial distribution structure of the scattered light, and calculating the defect size by using the scattered light intensity, thereby indirectly determining the defect information, and achieving the purpose of defect detection.It can provide a methodological reference for rapid detection of defects in the wafer industry application process.
  • Research on Near Field Characteristics of Symmetry Breaking multilayered nanoshells dimer
    JIANG Jiyu1*, JIANG Shasha2, LV Jingwei1, YU Xuntao3, LIU Chao1, MU Haiwei1
    The Journal of Light Scattering. 2020, 32(3): 251-258. https://doi.org/10.13883/j.issn1004-5929.202003009
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    Au-ITO-Ag symmetry-breaking multilayered nanoshells dimer were systematically investigated by near field enhancement characteristics based on the finite element method. The localized surface plasmon resonance properties are explained by the plasmon hybridization theory. The results show that the plasmon resonance peak of the symmetry-breaking multilayered nanoshells dimer is very sensitive to the change of the radius of the Au core. The electric field of the symmetry-breaking multilayered nanoshells dimer is mainly distributed on the surface of the nanoshells dimer, and the electric field intensity is most prominent in the Ag nanocup opening part, whose highly adjustable optical properties provide a solid theoretical basis for improving biosensor technology.
  • Low-temperature and high-pressure Spectroscopy study of Gallium Nitride
    FAN Chunmei1, LIU Jingyi1, LIU Shan1, TANG Qiqi1, WU Binbin1, WANG Xiaoli2 *, LEI Li1*
    The Journal of Light Scattering. 2020, 32(3): 259-265. https://doi.org/10.13883/j.issn1004-5929.202003010
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    In this work, we have study the low-temperature (77 K) and high-pressure Raman, photoluminescence (PL) spectroscopy and Heyd-Scuseria-Ernzerh (HSE) of hybrid functional theory calculation of wurtzite-type GaN based on our self-designed low-temperature and high-pressure experimental apparatus. The Raman spectroscopy indicates that the Raman vibration modes of GaN exhibit a blue shift at 77 K, but the blue shift gradually disappears at higher pressures. The PL spectroscopy shows that the zero-pressure band gap of GaN is 3.470 eV at the 77 K and it increases with increasing pressure. In addition, band gap values of GaN under high pressure have also been calculated by HSE hybrid functional theory. The pressure dependence of the calculated result is consistent with the experimental measurement. The energy of the exciton (ΓBX) increases with increasing pressure, and the relationship between the exciton energy (77 K) and pressure can be fitted to E(P)=3.470+2.89×10-2P+1.1×10-3P2 eV.
  • Embedding Metal Nanoparticles to Increase the Absorption Rate of Crystalline Silicon Thin Film Solar Cells
    XIAO Liang, ZHU Qunzhi
    The Journal of Light Scattering. 2020, 32(3): 266-273. https://doi.org/10.13883/j.issn1004-5929.202003011
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    In this paper, a structure of embedding metal nanoparticles in the Si layer of a crystalline silicon thin film solar cell is proposed. By controlling the shape, material and spacing of the metal nanoparticles, the LSPR effect excited by the metal nanoparticles surface is used to improve the absorption of light of crystalline silicon thin film solar cell. The micro-nano optical simulation software (FDTD) was used to simulate the Si layer absorption rate and photogenerated electron rate under different conditions. Compared with thin-film solar cells without embedded nanoparticles, when embedded in spherical Ag nanoparticles, the Si layer absorption rate is significantly improved in the range of 0.8~1.1μm, the overall absorption rate is increased by 23.1%, and the photogenerated electron density is significantly elevated around the nanoparticles. When embedded in the four nanoparticles of Ag, Au, Cu, and Al, the absorption rate curve fluctuates in the range of 0.45~1.1μm, and the absorption peaks in a wider range can be excited when the Al nanoparticles are embedded. Moreover, the overall distribution of the photogenerated electron density of the Si layer is best in the presence of Al nanoparticles. In the analysis of two Al nanoparticle spacings T of 0.1μm, 0.15μm and 0.2μm, the absorption rate was better when T was 0.1μm in the range of 0.45~0.75μm. When T=0.15μm, a wider absorption peak is excited than the other two cases near the 0.9μm and 1.0μm, and the overall photogenerated electron density is higher in the upper region of the Si layer.
  • A new Brillouin optical time domain localization technique
    JIANG Chao
    The Journal of Light Scattering. 2020, 32(3): 274-279. https://doi.org/10.13883/j.issn1004-5929.202003012
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    In the Brillouin Optical Time Domain Analysis (BOTDA) system, different pulse widths correspond to different spatial resolutions, but the Brillouin signals at different pulse widths overlap at the same position. The phenomenon was explained for the first time by pulse subdivision analysis. Based on this phenomenon, a new Brillouin optical time domain localization technique is proposed. Positioning the end point of the strain or temperature segment through two forward and backward measurements can improve the spatial resolution without reducing the pulse width, and overcome the limitation of the pump pulse width on the spatial resolution. And then experimentally verified. 1m long strain segment on a 24,711 m long fiber was localized by 20~100 ns pump pulse with a 10 ns of step. Strain value of 1880 μɛ with a measurement error of 36 μɛ was obtained by Lorentz bimodal fitting. Compared with other BOTDA positioning technologies, this technology does not need to reduce the pulse width to improve the spatial resolution, and it is simplicity and effectiveness. The method is believed to have extensive application prospects in distribution sensing fields.
  • Application of Spectrometry on Analysis of Blue and Green Pigments in the Thangka
    ZHANG Rui1, FANG Xiaoji, JU Jianwei
    The Journal of Light Scattering. 2020, 32(3): 280-287. https://doi.org/10.13883/j.issn1004-5929.202003013
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    The aim of this study was to analysize the blue and green pigment samples falling off from the Thangka Portrait of Vajrabhairava. 3D video microscope was applied to observe the morphology, particle size distribution, impurity. Laser Raman spectrum, infrared absorption spectrum, X-ray diffraction spectrum were used to show the chemical composition and crystal structure. According to the mutual confirmation of various spectral analysis results, the main component of blue pigment was azurite, while the main component of green pigment was malachite with good crystal structure. The spectroscopic method can provide a reference basis for the selection and protection of materials with a view the protection, repair and preventive protection of Thangka.
  • Study on Rapid Non-destructive Testing of Avocado Oil Based on Laser Raman Spectroscopy
    ZHANG Fengjuan1, HUANG Min2*, LIU Zhenfang2
    The Journal of Light Scattering. 2020, 32(3): 288-294. https://doi.org/10.13883/j.issn1004-5929.202003014
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    In this paper, the original avocado oil and normalized Raman spectra of avocado oil, palm oil, corn oil, mustard seed oil, walnut oil and flax seed oil were compared by a portable laser Raman spectrometer. The results showed that: avocado oil has two characteristic Raman peaks with weak and unique peaks at 1115 cm-1 and 1523 cm-1, and the unsaturation parameter value I1296/I1260 of avocado oil is much higher than that of 5 other oils. Raman spectroscopy was also used to detect 21 kinds of avocado oil actual samples. It was found that there was one sample Raman spectroscopy and that there were big differences in characteristic peak intensity and unsaturation parameters, such as I1296/I1260, which may be incorporated into other cheap oils. Fatty acid composition test was used to further verify that the sample was adulterated. Experimental results found that: the portable laser Raman spectrometer could be used for the rapid identification of avocado oil.
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