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there are also [Al2F7]− ion clusters in KAlF4 melt, and the content is about 1.75 mol%.
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Based on the principle of Local Surface Plasmon Resonance (LSPR), this paper uses the finite element method to study the method of adjusting the resonance wavelength of the silver cone nanoarray. COMSOL simulation software is used to simulate the variation of average electric field intensity near the surface of silver cone nano array with incident light. The results show that the resonance wavelength is related to the period of the array and the refractive index of the environment. With the increase of the period p of the conical array, the resonance wavelength is redshifted. There is a linear relationship between them, and the linear relationship between array period and resonance wavelength can be obtained by fitting according to effective wavelength theory: p=0.97λ+21.244. The variation of radius r and height h of cone has no effect on resonance wavelength. When the period of p is 560 nm, r=120 nm, h=200 nm, and the resonance wavelength peak reaches the maximum. The increase in the refractive index of the environmental medium leads to a red shift of the resonance wavelength, the peak height decreases, and multiple resonance peaks appear.
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The polarization images contains more information from surface and superficial surface than traditional image, so it can be used to detect and evaluate the skin state by obtaining the polarization information of abnormal and normal skin areas. This project built a multi-waveband laser-illuminated skin polarization imaging system, and carried out laser polarization images experiments on normal skin, pigment deposition region and inflammation region under blue, green and red three-waveband laser illumination. The main results were as follows: 1) Under 488nm blue light and 520nm green light laser illumination, the polarization degree data of the pigment deposition region, the inflammation region and the normal skin area were significantly different; 2) Under 660nm red laser illumination, there was a significant difference between the pigment deposition region and the normal skin area, but the data of the inflammatory region and the normal skin region were similar; 3) The polarization image information of the three-wavelength laser for the pigment deposition region is similar. The comprehensive analysis shows that the polarization image and polarization degree data of simulated skin under green laser illumination can easily distinguish the interface and difference between normal skin and pigment deposition and inflammatory skin area. The polarization images of the pigment deposition region are more similar, showing the same subcutaneous depth information. The polarization image of the inflammatory region has great difference, which is the polarization information of the skin at different depths.
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According to the needs of classification and identification of many varieties of soybean in Northeast China, this paper uses the research method of combining theoretical calculation and experimental analysis to carry out the classification and identification of 6 varieties of soybean. Oleic acid and linoleic acid are important components of soybean. Firstly, based on density functional theory, the molecular spatial structures of oleic acid and linoleic acid were constructed, and the theoretical Raman spectra were optimized and calculated by B3LYP/6-31+G(d,p) basis set. Then, the Raman spectra of oleic acid, linoleic acid analytical purity and six varieties of soybean were obtained by experiment, and the theoretical Raman spectra were compared with the experimental Raman spectra. It was found that all varieties of soybean had strong Raman peaks at 1281, 1445, 1662 and 2904 cm-1. Finally, taking the four Raman peaks as the characteristic peaks, the principal component analysis (PCA) and linear discriminant analysis (LDA) were used to visually classify different varieties of soybeans, and the classification accuracy reached 90%. The results show that density functional theory combined with Raman spectroscopy can effectively classify soybean varieties, which provides a certain reference for the development of intelligent agriculture.
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Currently, 90% to 98% of the natural colorless diamonds on the market are usually Ia type（Includes IaA, IaAB, IaB）, colorless synthetic diamonds are mainly II type（includes IIa, IIb）. The spectral characteristics of natural diamond, synthetic diamond at high temperature and high pressure（HTHP） and chemical vapor deposition (CVD) were studied by using ultraviolet fluorescent lamp, Gem Microscope, Fourier transform infrared (FTIR), ultraviolet visible near infrared absorption spectrum(UV-Vis-NIR) and confocal laser Raman spectroscopy. The Raman spectra of 1335cm-1 were fitted by Lorentz, and the FWHMt was obtained. The results were analyzed by one-way ANOVA. The results show that the long wave fluorescence of natural diamond is stronger than that of short wave, and that of synthetic diamond is stronger than that of long wave. Cloud like inclusions, light crystalline inclusions and dark inclusions can be seen in natural diamond, Fe、 Ni metal catalyst inclusions can be seen in high temperature and high pressure synthetic diamond, and point inclusions can be seen in CVD synthetic diamond. High temperature and high pressure samples are magnetic. The infrared absorption spectra show that the natural diamond has obvious absorption peaks at 1179cm-1, 1282cm-1 and 1365cm-1, belonging to IaAB type; the synthetic diamond has no obvious nitrogen related absorption at 1332-1-1100cm-1, belonging to type II. UV-Vis-NIR spectra show that natural diamond has an absorption peak of 415nm (N3), while synthetic diamond has no such absorption peak. The Raman shifts of natural diamond and synthetic diamond are the same. The full width at half height of natural diamond is more than 6.0 cm-1, and that of synthetic diamond is less than 6.0 cm-1. It provides a theoretical basis for the identification of natural diamond and synthetic diamond.
