30 September 2018, Volume 30 Issue 3

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  • The Journal of Light Scattering. 2018, 30(3): 197. https://doi.org/10.13883/j.issn1004-5929.201803001
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    Based on discrete dipole approximation (DDA), the effect of peak value and the peak position of optical absorption spectrum of Au@Ag core-shell nanostructure was systematically studied by the factors such as shell material, size and morphology. The results show that the calculations of Au spherical nanoparticles in the liquid environment are in agreement with the results calculated by the Mie theory, indicating that the optical properties of the Au@Ag core-shell nanoparticles after the cubic spline interpolation of the optical constants are accurate and reliable. With the increase of Ag shell thickness, the absorption spectrum of Au@Ag core-shell spherical nanoparticles forms different acromion with the spectrum of gold spheres, then the main peak shifts to red and the blue-shift of acromion vanishes,which becomes an optical absorption peak, and the intensity of optical absorption peak is enhanced. The optical absorption spectra of Au@Ag core-shell nanocube shows many secondary absorption peaks at <450nm. With the growth of Ag shell thickness, the primary and secondary absorption peaks enhance, and the main absorption peak shows obvious blue-shift. The Ag shell not only changes optical absorption intensity and the location of peak value, but also forms strong surface plasma resonance (SPR) at the tip of Au@Ag core-shell nanoparticles, and improves the effect of Ag on optical absorption.
  • The Journal of Light Scattering. 2018, 30(3): 203. https://doi.org/10.13883/j.issn1004-5929.201803002
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    The LSPR spectroscopy of Ag nanoparticles is sensitive to the changes of surrounding medium, which enables the nanoparticles to serve as plasmonic nano sensors. In this paper, the spectroscopy and sensing performance of nanosphere are investigated by employing the Mie theory in absorbing medium. The results show that when the imaginary part of the complex refractive index of the medium is small, its influence on the LSPR spectroscopy and the sensing performance can be neglected; The LSPR spectroscopy changes greatly, and the sensing performance of nanosphere decreases with the increase of the imaginary part. The LSPR peak disappears when the imaginary part of surrounding medium is large enough, then LSPR spectroscopy is not suitable for sensing.
  • The Journal of Light Scattering. 2018, 30(3): 209. https://doi.org/10.13883/j.issn1004-5929.201803003
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    Surface-enhanced Raman scattering (SERS) can paves the way for the trace detection of low-concentration analyses, even single molecular detection, and owns greatly potential application prospect in chemistry, biology, environment, and so on. Development of high-performance SERS substrate is one of the most import research topic in SERS technology. In this work, we achieve the fabrication, characterization, and SERS effect research of a kind of high-performance, low-cost, and large area SERS substrate. The Raman scattering intensity from R6G molecule can be effectively enhanced by this SERS substrate for about five times when compared with that with roughness Au film. We carry out systematic numerical simulation and experiment research on the influence of micro-sphere diameter and nano-particle height on the Raman scattering enhanced factor, and find an optimized structure parameters. Our work will provide a kind of high-performance SERS substrate.
  • The Journal of Light Scattering. 2018, 30(3): 217. https://doi.org/10.13883/j.issn1004-5929.201803004
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    Volatile organic compounds, as a general species in the natural environment, produced significant impact on human health. Therefore, the rapid technique for the in situ detection on VOC is high desired. In this study, the uniform 30 nm spherical Au nanoparticles were synthesized by chemical method, which had surface enhanced Raman effect and high chemical stability. Using the nanoparticles as a unit, an Au nanoparticles monolayer film (Au MLF) with remarkable enhancement and good SERS signal uniformity was assembled at the air/water interface. Using the Au MLF as a SERS substrate, the volatile organic compound has been detected. And then, to realize the SERS detection of volatile organic compound with weak adsorption on substrate, we fabricated the polydimethylsiloxane (PDMS) coated Au MLF composite substrate (PDMS-Au MLF) to improve the SERS detection ability. Using this non-contact detection method, we can realize SERS detection of various VOCs.
  • The Journal of Light Scattering. 2018, 30(3): 223. https://doi.org/10.13883/j.issn1004-5929.201803005
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    Five different kinds of crystalline structures in the Li2O-WO3 binary system were selected and an ensemble of eight cluster models containing Na+ cation was built in this paper. DFT (density functional theory) calculation of their Raman-active vibration wavenumbers together with scattering activities were performed based on MS (Materials Studio) CASTEP (Cambrigde Serial Total Energy Package) Program and Gaussian09 code, respectively. The wavenumber of W-Onb (non-bridging oxygen) Raman symmetric stretching vibration mode were found to increase with the decrease of W-Onb bond length not only for crystals but also for melts. In order to reflect the influence of local stress on the wavenumber of W-Onb symmetric stretching vibration mode, the micro-structures in crystals and melts were identified, respectively. Results show that bulk crystals usually contain [WO6]6- coordinated groups in the Li2O-WO3 binary system, the wavenumber of W-Onb symmetric stretching vibration mode in [WO6]6- will increase with the increase of the number of bridging oxygen; while in the melt, the wavenumber of W-Onb symmetric stretching vibration mode generally follows: [WO4]2- > [WO5]4- > [WO6]6-. When the W-O group is determined, this wavenumber will increase with the increase of the number of bridging oxygen. The correlation is helpful for the diagnosis and identification of the anion groups in the crystalline and molten alkali tungstate compounds. The in-situ Raman spectra of molten A2WnO3n+1 (A = Li, Na, K; n = 1, 2, 3) have been measured in order to verify the correlation obtained in this paper.
  • The Journal of Light Scattering. 2018, 30(3): 230. https://doi.org/10.13883/j.issn1004-5929.201803006
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    Colloidal semiconductor nanocrystals (NCs) and in particular nanorods, further the heterostructured nanocrystals have created tremendous interest to date due to their unique optical properties, such as efficient and tunable light emission via size control as well as the simple fabrication. CdSe/CdS dot-in-rods is one of the most typical specimen, whose absorptions depend on the nanorod shell while the emitting wavelength is determined by the core size. In this letter, acoustic vibrations (5-50 cm-1) of CdSe quantum dots, CdSe/CdS core-shell quantum dots with giant shell, CdS nanorods and CdSe/CdS dot-in-rods that consist of a CdSe core and a rod-shaped CdS shell are studied by non-resonant Raman spectroscopy. The phonon modes in the ULF region can be clearly assigned by their polarization behavior and Lamb’s theory to extensional and breathing modes of the NCs. The electronic Raman scattering are observed in rods and dot-in-rods in the meanwhile. Furthermore, in dot-in-rods the dominant RBM is red-shifted with respect to bare nanorods, which can be analyzed quantitatively in terms of local reduction of sound velocity. Finite element simulations using Comsol software reveal the intricate distribution of strain induced by the acoustic vibrations, and particularly the localization of the RBM in the core region in core-shell architectures. The localization of the acoustic phonons in certain regions of the rod influences their resonant frequency, which together with their spatial overlap with the electron and hole wave functions can be expected to affect coupling to band edge excitons, and therefore impact their light emitting properties.
  • The Journal of Light Scattering. 2018, 30(3): 236. https://doi.org/10.13883/j.issn1004-5929.201803007
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    The need for alternative energy sources is growing stronger due to the increasing energy demand and environmental concerns. Here we designed the surface plasmon resonance (SPR) promoted solar fuel cells by tailoring a Au core Pd shell Pt mushroom structure nanoparticles to enhance the catalytic activity of the direct methanol fuel cells (DMFCs). The combination of the Pd and Pt provides a synergistic effect while the Au core provides the photothermal and photoelectrocatalytic effect by SPR under irradiation to enhance the catalytic activity of the electrooxidation of methanol. A complex synergistic effect is achieved by using all three metals in combination, and the whole is greater than the sum of its parts. The temperature on the nanoparticle surface after illumination are detected by surface-enhanced Raman scattering (SERS) with a probe molecule of 4-methoxyphenyl isocyanide. The photoelectrocatalytic effect generated from SPR is proved by SERS with a probe molecule of p-aminothiophenol (PATP). Most importantly, the quantitative calculation of the ratio of the photothermal and photoelectrocatalysis effect contributed to the catalytic activity is realized. These results provide a novel design of catalysts for the solar fuel cells based on the SPR effect.
  • The Journal of Light Scattering. 2018, 30(3): 245. https://doi.org/10.13883/j.issn1004-5929.201803008
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    The fluorescent brighteners in soap were qualitatively measured by fluorescence spectroscopy and Raman spectroscopy. A total of 46 brands of soap and 8 kinds of fluorescent brighteners were studied in the common 19 brands. The fluorescence spectra and Raman spectroscopy were used to detect the samples, and whether the soap samples contained the fluorescent brighteners and their kinds according to the spectral results. The results show that eight kinds of soap have fluorescent brighteners, seven kinds of packaging ingredients Tab marked, but there are six inaccurate, one is not marked with its fluorescent whitening agent composition.
  • The Journal of Light Scattering. 2018, 30(3): 251. https://doi.org/10.13883/j.issn1004-5929.201803009
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     Association species distribution and the transformation relationship among species in the calcium nitrate solution with water and salt molar ratio (WSR) of 4.0 ~ 160.0 were studied by Microscopic Raman spectroscopy. The results showed that the symmetric stretching vibration frequency (v1-NO3-) of nitrate ions in solution was shifted from 1048.3 cm-1 to 1052.9 cm-1, and FWHM (the full width at half-maximum) was changed from 7.6 cm-1 to 15.3 cm-1 with the WSR decreased from 160.0 to 4.0. The v1-NO- peak was studied by the component analysis method. It was found that WSR≥16.3 was the first concentration region, the main species was Shared ion pair (SIP), the second species was Contact ion pair (CIP) and Free hydrated ion (Free ion), there wse the same amount of SIP and CIP when WSR = 16.3; it was the second concentration region when 8.4≤WSR<16.3, The main species was CIP, the amount of complex structure (Complex) was increased; it was the third concentration region when WSR<8.4, The main species was Complex, the amounts of CIP and SIP was decreased rapidly; When WSR <4, CIP and SIP were transformed rapidly into Complex, the amount of Complex approached 1. The higher the supersaturation of calcium nitrate solution is, the more difficult the crystallization be. The structure of this solution was similar to molten salt of calcium nitrate tetrahydrate, the structural configuration of the calcium nitrate solution(1≦WSR≦4, new phase is not generated) might be monodentate hexacoordination.
  • The Journal of Light Scattering. 2018, 30(3): 258. https://doi.org/10.13883/j.issn1004-5929.201803010
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    This paper mainly about that rapidly detecting the types and concentration of residual organic solvents in wastewater by portable Raman spectrometer. Firstly, using a portable Raman spectrometer to establish a standard Raman spectrum. Then, using the same portable Raman spectrometer to test wastewater samples and comprising with the standard spectrum. Finally, the organic solvent types and concentration in wastewater were calculated. This is a simple, sensitive and rapid method and it is of great significance for monitoring the let out of wastewater in real time.
  • The Journal of Light Scattering. 2018, 30(3): 264. https://doi.org/10.13883/j.issn1004-5929.201803011
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    In the two step hydrogen process of solar thermochemistry, with the change of volume fraction and th-ickness of optical path, the physical properties of metal oxide particles play an important role in the transmission of radiation energy in the reaction process of particles. In order to obtain the spectral radiation characteristics of ZnO particles, firstly, the spectral transmittance of ZnO metal oxide particles at 300~1200 nm was measured by suspension method. Secondly, the radiation characteristics of ZnO metal oxide particles with volume average size d43=13.9 μm and area average particle size d32=7.71 μm are studied theoretically. The results shows that for d32=7.71 μm, its attenuation, absorption and scattering coefficients are about 2 cm-1, 0.8 cm-1 and 1.2 cm-1 respectively, and for d43=13.9 μm, its attenuation, absorption and scattering coefficients are close to 1.1 cm-1,0.5 cm-1 and 0.6 cm-1 respectively. By analyzing the scattering phase function and the scattering asymmetry factor, it is known that the light is dominated by the forward scattering in the propagation, so that the sunlight is more likely to penetrate into the inner part of the particles. Then the spectral transmittance of two kinds of particles is calculated by Mie theory and BEER’s law. By comparing with the experimental results, it is found that the transmittance of the particle system represented by the area average size d32 is closer to the experimental results. Finally, using the average particle size and Monte Carlo method to simulate the hemispherical transmittance, hemispherical absorption rate and hemispherical reflectivity of different thickness and volume fraction.
  • The Journal of Light Scattering. 2018, 30(3): 271. https://doi.org/10.13883/j.issn1004-5929.201803012
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    The disadvantages of traditional single-wavelength anti-reflective(AR) coating design are analyzed. Based on the reflectivity index data of coating material in the ultraviolet, visible and near-infrared regions, the proper multilayer coating design is obtained. By manufacturing the offset shutter and by optimizing the process parameters in ion-assisted deposition, the optimized technology of three wavelength anti-reflective coating is found and the three wavelength anti-reflective coating spectral shift caused by temperature is small after one month in air. The reflective index in 1053 nm and 527 nm is below 0.5%.and the reflective index in 351 nm is below 0.2%.
  • The Journal of Light Scattering. 2018, 30(3): 277. https://doi.org/10.13883/j.issn1004-5929.201803013
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    Cotton is an important natural fiber. If waste textiles can be classified and recycled according to its cotton content, the consumption of natural fiber resources can be greatly reduced. However, the current recycling of waste textiles mainly uses manual sorting method. This method has low efficiency and high cost. It is difficult to meet the needs of large-scale fine sorting and grading of waste textiles. Near infrared spectra analysis method was used in this paper to determine the cotton content of waste textiles. By using the support vector machine method based on the principal component analysis, a qualitative analysis model of near infrared spectroscopy of waste textiles was established. The model can well separate the two types of waste textiles, cotton-containing and cotton-free. For the waste textile samples that contain cotton, a near infrared spectra analysis model of the cotton content of waste textiles was built using a multi-model method. The model has good prediction results. Using the above two models in combination, the cotton content of the waste textile samples can be better determined. This new method is expected to be used for rapid determination of some other natural fiber content in waste textiles.
  • The Journal of Light Scattering. 2018, 30(3): 284. https://doi.org/10.13883/j.issn1004-5929.201803014
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    Raman scattering and Brillouin scattering are two phenomena, which are most representative  in the inelastic light scattering, they were named by using C. V. Raman and L. Brillouin who are Indian and American of France descent scientists, respectively. The cognition (including phenomena, theory and their applications) of the former is more deepen than the latter, for people. Therefore, L. Brillouin and Brillouin scattering will only have been given more details in this summarize.