30 June 2016, Volume 28 Issue 2
    

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  • Enhancement of Near-infrared Graphene Absorption with Metal-Dielectric Nanostructure
    The Journal of Light Scattering. 2016, 28(2): 97-101. https://doi.org/10.13883/j.issn1004-5929.201602018
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         Graphene, a two-dimensional monatomic layer of carbon material, shows its weak absorptance of only about 2.3% in the visible and near infrared region. This dramatically limits its application in graphene-based solar cells and photon detection. In this letter, we propose a metal-dielectric periodic nanostructure to enhance the absorptance of graphene based on the magnetic resonances. Using finite-element method, we numerically simulated the effect of the structural parameters of the nanostructure on the absorptance of graphene layer. Our calculations show that the absorptance of graphene can be enhanced by about 4 times with specific structural parameters. Inductor-capacitor (LC) circuit model is applied to reveal the mechanism behind the absorption enhancement of graphene. The LC model succeeds in predicting the magnetic resonances, which are independent of the presence of the graphene. Our proposed nanostructure, which is easy for practical fabrication, is expected to have potential applications in the design of novel graphene-based optical and optoelectronic devices.
  • Study on Expansion Coefficient of Scattering Phase Function for Ice Crystal Particles
    The Journal of Light Scattering. 2016, 28(2): 102-105. https://doi.org/10.13883/j.issn1004-5929.201602001
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    Expansion coefficients of ice crystal phase function can be used as input parameter in atmospheric radiative transfer calculations. In this paper, the phase functions of ice crystal with surface severe roughness are expanded by the generalized spherical functions, and the characteristics of expansion coefficients are analyzed for GHM, COL and ASC ice crystal particle model. The simulating results present the efficiency of generalized spherical function method for ice crystal particles with severe surface roughness.

  • Preparation of Filter Paper-Based Surface-Enhanced Raman Scattering（SERS）Substrate and Its Application for Seminal Plasma Analysis
    The Journal of Light Scattering. 2016, 28(2): 106-111. https://doi.org/10.13883/j.issn1004-5929.201602002
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      This article introduced a filter paper-based SERS substrate through soaking method, and investigated the relationship between the distributions of silver nanoparticles (AgNPs) on the filter paper with soaking time in detail. SERS spectra of seminal plasma under different excitation wavelengths (514 nm and 785 nm) were compared, and the latter was confirmed to demonstrate better SERS signals. SERS and normal Raman spectra of seminal plasma using 785 nm excitation laser was compared as well. More importantly, the intensity of the strongest peak (654 cm-1) from SERS spectra of seminal plasma was used to evaluated the enhancement effects and signal reproducibility with filter paper SERS substrates under different soaking time(6 h,12 h,24 h). Our results indicated that the AgNPs on the paper substrate soaked with concentrated AgNP colloid presented a relatively uniform distribution at the soaking time of 12 h and the substrate demonstrated high Raman signal enhancement and good signal reproducibility as well.
  • Density Functional Theory Study on Surface-Enhanced Raman Spectra of Phenothiazine
    The Journal of Light Scattering. 2016, 28(2): 112-115. https://doi.org/10.13883/j.issn1004-5929.201602003
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        Phenothiazine is a heterocyclic compound containing N, S, has a large delocalized π bond. With Gaussian 09 program, at the B3LYP method, Ag atoms using Lanl2dz pseudopotential basis set, C, H, N, S atoms using 6-31++G (D, P) basis set to optimize and calculate the phenothiazine and phenothiazine hydrochloride silver with the Raman spectra of the compounds (PTH-Ag), and the GaussianView of PTH molecule to belong and phenothiazine residues in food and products of qualitative and quantitative determination of provide a theoretical basis. The results show that the more Ag atoms are connected, the more obvious enhancement effect.
  • SERS Effect of Au Micro/Nanoparticle Arrays
    The Journal of Light Scattering. 2016, 28(2): 116-119. https://doi.org/10.13883/j.issn1004-5929.201602004
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      Surface-enhanced Raman scattering (SERS) can provide “fingerprint” characteristic of molecular vibration with high sensitivity and rapid response, and thus is a promising analytical technique. The intensity of molecular Raman signal will be amplified by several orders and the so-called SERS effect occurs when molecules locate on the surface of noble metal or some semiconductor nanostructures. Therefore, nanostructured SERS substrates are essential to SERS effect. Here we report that Au micro/nanoparticle arrays are fabricated on a Si wafer by a simple electrodeposition approach. There are many nanoscale gaps between the neighboring nanoparticles, which can provide SERS "hot spots" upon laser excitation, therefore the arrays of Au micro/nanoparticles have high SERS sensitivity. Additionally, the Au micro/nanostructures are highly stable in both chemical and structure. The as-prepared Au micro/nanostructures showed high SERS sensitivity to ultratrace (10-12 M) rhodamine 6G (R6G) with good SERS signal uniformity. Successful detection of toxic methyl parathion with a low concentration in water was achieved by using the as-prepared Au micro/nanostructure arrays as SERS substrates. This result shows the promising application of our Au micro/nanostructure arrays in SERS monitoring of toxic organic environmental pollutants.
  • The SERS Spectra Detection of Fenpropathrin on Nano-silver Films
    The Journal of Light Scattering. 2016, 28(2): 120-124. https://doi.org/10.13883/j.issn1004-5929.201602005
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      In our work, polyvinyl alcohol (PVA) protected silver nanoparticles assemble on aluminum sheets was prepared and employed to detect Fenpropathrin acetone (10-4-10-7 mol/L). In the process of the experiment, the near-infrared laser beam (785 nm) was used as the excitation light source. The high-quality near-infrared surface-enhanced Raman scattering (NIR-SERS) spectra of fenpropathrin were obtained in the ranges of 200 to 2000 cm-1 and the detection limit of fenpropathrin acetone was down to 10-6 mol/L. To verify the spectral reproducibility of the silver films, the spectra of fenpropathrin acetone with two various concentrations (10−4 mol/L and 10−5 mol/L) were detected which on six different nano-silver films. The results show that the nano-silver films have highly spectral reproducibility when detected fenpropathrin acetone.
  • Raman Scattering Studies on CVD Grown Cubic SiC Thin Films on Si
    The Journal of Light Scattering. 2016, 28(2): 125-130. https://doi.org/10.13883/j.issn1004-5929.201602006
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        Cubic (3C)-SiC films were grown on Si (100) substrate by chemical vapor deposition (CVD). The microstructures and optical properties of 3C-SiC films have been studied by spectroscopic ellipsometry (SE) and Raman scattering. Raman scattering and SE were used to characterize 3C-SiC materials. From the analysis of SE we can obtain thickness of 3C-SiC films. Also from the analysis of Raman spectra, we can see the line shape of TO mode and LO mode from the fitting result, and the correlation length and carrier concentration were obtained. The result of correlation length reveals that the crystalline quality is expected to improve with film thickness increasing and Raman scattering spectra also shows the effects of the epilayer thicknesses.
  • Dispersive Spectra and Scattering Rates of Interface Optical Phonon Modes in a Wurtzite GaN-Based Step Quantum Well with Strong Built-in Electric Field
    The Journal of Light Scattering. 2016, 28(2): 131-139. https://doi.org/10.13883/j.issn1004-5929.201602007
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         Electron-interface optical (IO) phonon scattering rates in a wurtzite GaN-based asymmetrical step quantum well (QW) are theoretically analyzed by using the usual Fermi golden rule. Based on the dielectric continuum model and Loudon's uniaxial crystal model, the analytical IO phonon states and their Fröhlich electron-phonon interaction Hamiltonian are derived. Taking into consideration the effects of strong built-in electric field (BEF) and the band nonparabolicity, the exact electronic eigen-states in the step QW are also obtained with the aid of two Airy functions. Numerical calculations on a wurtzite AlN/GaN/AlxGa1-xN/AlN step QW are performed. It is found that there are four branches of IO phonon modes in the asymmetric nitride step QWs, which is obviously different from the situation of symmetrical GaN/AlN single and coupling QWs. This is mainly ascribed to the asymmetry of the step QW structures studied here. The calculated results show that the intrasubband and intersubband scattering rates in wurtzite step QWs are one order of magnitude larger than those in GaAs-based step QWs, which is attributed to the larger electron-phonon coupling constants of GaN-based materials. The intrasubband scattering rates in wurtzite step QWs behave analogous dependent relation as those in cubic GaAs-based step QWs on the structural parameters, but the intersubband scattering rates here show obviously di®erent dependent behavior on the structural parameters. This is ascribed to the effects of the strong BEF and the band nonparabolicity. Moreover, the high-frequency IO modes play more important role to the total scattering rates than the low-frequency ones.
  • Ethyl α-cyanoacrylate studied by Raman spectroscopy
    The Journal of Light Scattering. 2016, 28(2): 140-143. https://doi.org/10.13883/j.issn1004-5929.201602008
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    Ethyl α-cyanoacrylate is a widely used adhesive, which is commonly known as superglue. In recent years, it was also being used as a background for detect the exogenous substances present in latent fingerpints by Raman measurement. Only half of the Raman modes have been assigned in earlier paper, and the assignment is not very accurate. The Raman spectrum of ethyl α-cyanoacrylate which is used in this article was obtained from experiment. Compare with the well-assigned organic compound such as acrylic acid, compound with ethyl group, and compound with cyan group, and considering the polymerization of the ethyl α-cyanoacrylat monomers, the 20 Raman active modes of ethyl α-cyanoacrylate have been assigned elaborately.
  • Raman Investigation of GZO Ceramiecs
    The Journal of Light Scattering. 2016, 28(2): 144-148. https://doi.org/10.13883/j.issn1004-5929.201602009
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    Pure ZnO ceramics and GZO (Ga:ZnO) ceramics were prepared by solid phase reaction method. We measured GZO ceramics with different Ga concentration by Raman spectroscopy and X-ray diffraction, and studied the variation of Raman spectra of the samples. The results showed that pure ZnO and GZO ceramics were maintained a hexagonal wurtzite structure. E2(low) and E2 (high) who were the characteristic bands of ZnO were found in 98 cm-1 and 437 cm-1, respectively. There appeared new bands at the 584 cm-1 and 631 cm-1 in the Raman spectra of GZO ceramic. And the band at around 1148 cm-1 corresponding to an overtone of E1(LO) mode has also undergone some changes with the increasing of Ga doping concentration. We assigned the vibration mode of the new band and the change of the original band after doping, which for 631 cm-1,we believed that this band is attributed to the local vibration mode that the substitution of Ga for Zn with O. (LVMGa-O) .
  • In-situ Raman Spectroscopic Study of the Molten Tungstates in Li2O-WO3 Binary System
    The Journal of Light Scattering. 2016, 28(2): 149-152. https://doi.org/10.13883/j.issn1004-5929.201602010
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    Joint analysis of in-situ high-temperature Raman spectroscopy and quantum chemical ab initio calculation on the evolution of the structure units existed stably in melts with the compositions within Li2O-WO3 binary system was carried out and the specfic model clusters of the micro structures in melts with different compositions were proposed in this paper, and the major vibrational modes were also assigned successfully. Results indicate that different compositions of melt result in the formation of chains of various lengths from joined [WO4]2- tetrahedra vertices, and smaller mole ratio of Li2O/WO3 tends to form longer chains. The following conclusion can be made based on the simulated results of quantum chemistry ab initio calculation: when the mole ratio of Li2O/WO3 in the melt is 1:1, 1:2, 1:3 and 1:4, the corresponding anion complex is [WO4]2- , [W2O7]2-, [W3O10]2- and [W4O13]2-, respectively. And the [W2O7]2-, [W3O10]2- and [W4O13]2- are made up of two, three and four [WO4]2- by sharing corners, respectively.
  • Experimental and theoretical investigation on the spectra of hydrated and anhydrous 3,4,5-THBA
    The Journal of Light Scattering. 2016, 28(2): 153-162. https://doi.org/10.13883/j.issn1004-5929.201602011
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    In this study, hydrated and anhydrous polymorphs of 3,4,5-trihydroxybenzoic acid (3,4,5-THBA) were characterized by Fourier transform infrared (FT-IR), Raman and terahertz (THz) spectroscopic techniques at room temperature. The density function theory (DFT) calculation with B3LYP method is applied to simulate the corresponding optimized structures and vibrational frequencies. The different vibrational modes are assigned by comparison between the experimental and theoretical spectra of two polymorphs. There is obvious difference within the molecular vibrational modes of hydrated 3,4,5-THBA and those of anhydrous one. The results show that the interactions between water and 3,4,5-THBA molecules make molecular configurations significantly different within hydrated and anhydrous polymorphs. This work offer the experimental and theoretical benchmark for identifying pharmaceutical polymorphs and also further studying the intramolecular and intermolecular interactions with spectroscopic technologies.
  • Rapid qualitative identification method of species of blood based on PCA with Raman Spectroscopy
    The Journal of Light Scattering. 2016, 28(2): 163-167. https://doi.org/10.13883/j.issn1004-5929.201602012
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    In the paper 3 kinds of animal for a total of 30 animal blood samples and 21 human blood samples were chosen as the typical tested objects. Principle component analysis (PCA) method was employed to quickly identify the species of blood samples based on Raman spectroscopy. Vector normalization was used to preprocess the Raman spectroscopy signal. According to the plot of Leverage value vs. Studentized residue, outlier sample was detected and removed. By the PCA method, the correct rate between animal blood samples and human blood samples was up to 95% based on PC1and PC2. Further on the basis of PC4 and PC5, the correct rate of identification the animal blood sample was above 90%. The experiment results showed that the PCA method had good application prospects and feasibility to identify the species of blood samples. This method provided a reference for processing the similar problems in the field of forensic science and life science.
  • The Interaction of Supported Planar Lpid Bilayers Containing Ganglioside-GM1 with Aβ on Different Substrates
    The Journal of Light Scattering. 2016, 28(2): 168-174. https://doi.org/10.13883/j.issn1004-5929.201602013
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    Supported planar lipid bilayers are artificial lipid bilayer membranes. Surface structures and properties of the solid substrates can affect the formation process, fluidity, two-dimensional structure and chemical activity of the SPBs, then affect properties of protein. Even on mica and SiO2 surfaces, which are flat and biologically inert, and most widely used as the substrates for the supported lipid bilayers, cause differences in the structure and properties of the supported membranes. In this review, by performing Raman spectroscopy, we analyzed the conformation of SPBs at mica and SiO2. Futhermore, we added the monomer amyloid-beta peptides onto SPBs. The differences between the conformation of amyloid-beta at mica and SiO2 are shown by Raman spectroscopy with different incubation time.
  • Analysis of Vibrational Spectra of Niacin based on Density Functional Theory
    The Journal of Light Scattering. 2016, 28(2): 175-181. https://doi.org/10.13883/j.issn1004-5929.201602014
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    The Raman and infrared spectra of niacin were measured experimentally. The molecular equilibrium geometries, vibrational frequencies, Raman and infrared intensity of niacin were calculated using the B3LYP level and cc-PVDZ basis set. Normal mode analysis was carried out using the program GAR2PED and the assignment of fundamental vibrations for niacin was obtained according to the potential energy distributions (PED). This study provides us with more quantitative vibrational spectral information which was not mentioned in previous literatures.
  • Study on the Absorption of Laser in the Radiation Fog
    The Journal of Light Scattering. 2016, 28(2): 182-184. https://doi.org/10.13883/j.issn1004-5929.201602015
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    This paper presents the simulated laser absorption coefficient of the radiation fog in the THz regime. The results are obtained based on the effective dielectric constant of the mixture, which is calculated using the Maxwell- Garnett formula in high frequency regime. Our numerical result based on MATLAB simulation suggests that the laser absorption is proportional to the imaginary part of effective dielectric constant, as well as the visibility of the fog. We also calculated the frequency-dependent absorption coefficient, which shows a peak feature at about 5 THz and saturates to a small value at high frequencies.
  • A study on fluorescence microscopy measurement method of articular cartilage
    The Journal of Light Scattering. 2016, 28(2): 185-189. https://doi.org/10.13883/j.issn1004-5929.201602016
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       Based on the auto-fluorescence property of collagen in articular cartilage, the research on fluorescence microscopy measurement method of articular cartilage was carried out. First, the difference between the healthy and pathological samples was revealed by statistical comparison of fluorescence images. Second, based on the polarization property of fluorescence, the fluorescence anisotropy of the cartilage was presented by the linear dichroism method, which lays foundation for research on structure of articular cartilage using fluorescence anisotropy method. Compared to traditional microscopic measurement techniques that supply the morphology and the super-structure of cartilage tissues, fluorescence microscopy measurement methods are able to obtain the information about the structure of cartilage tissues. The results presented in this paper open the door for developing new diagnostic method for articular cartilage diseases.

  • Effects of Different Particle Size on the Charge Transfer between CdS QDs and Cobaloxime Studied by Photoluminescence Spectroscopy
    The Journal of Light Scattering. 2016, 28(2): 190-194. https://doi.org/10.13883/j.issn1004-5929.201602017
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       In this work, steady-state and time-resolved photoluminescence (PL) spectroscopy were applied to study the effects of CdS particle size on the charge transfer between CdS quantum dots (QDs) and cobaloxime (CoⅢ(dmgH)2(3-(OH)py)Cl) in CdS QDs-cobaloxime hybrid photocatalytic hydrogen production system. All three kinds of CdS QDs with different particle size (3.9, 4.4 and 5.0 nm) show a band-edge emission and a broad trap-related emission. When the particle size of CdS QDs is smaller, the band-edge emission intensity is reduced while the trap-related emission enhanced, and CdS QDs with smaller particle size exhibit longer emission lifetime. Upon mixing with cobaloxime, the band-edge emission and trap-related emission of CdS QDs are quenched quickly, and the quenching constant of the trap-related emission is bigger than that of the band-edge emission. The emission intensity of CdS QDs is quenched more efficiently with the particle size decreasing. These results demonstrate that, both the free and trapped charge carriers of CdS QDs could transfer to cobaloxime, and the trapped ones transfer to cobaloxime more efficiently; CdS QDs with smaller particle size exhibit higher charge transfer efficiency.
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