Papers by Keyword: Raman Spectra

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Authors: Chen Dong, Zhi Chao Wei, Bo Liu
Abstract: The sequential microhydration of sodium glycinate is investigated at the MP2/6-311++G(d,p) level. Our results clearly indicate that the microhydration process is driven by the charge site of sodium cation and a bridge site is losing its dominant position. Eventually, a comparison of theoretical and experimental Raman spectra provides the evidence of the predicted structural information.
Authors: Lei Lei Xiang, Zuo Liang Sha, Liang Zhu
Abstract: Raman spectra are sensitive to solute, solid or polymorphs concentrations, particle size distribution and temperature. Characteristic peak positions of tibolone and acetone were observed at 1559cm-1 and 787cm-1. In this paper, we used the LabRAM HR800 System to detect the Raman spectra of 11 undersaturated standard solutions (concentration range 0-150 mg/ml) at 40°C; built model that estimating concentration of tibolone in acetone solvent by relating peak intensity ratio of the components to the concentration of the solution, and the mean estimated error was only 1.723% in the testing data. The results indicate that this method of estimating concentration is feasible and simple.
Authors: Mohd Syamsul Affendy bin Mohd Saidi, Sib Krishna Ghoshal, Ramli Arifin, Mohamad Khairil bin Roslan
Abstract: Obtaining enhanced up-conversion efficiency in rare earth ions doped inorganic glass by means of noble metal nanoparticles (NPs) embedment remains challenging. For the first time, we report the combined effects of silver (Ag) and titania (TiO2) NPs embedment on the structural and absorption characteristics of dysprosium (Dy3+) doped tellurite glass. Transparent and thermally stable glass samples were prepared using conventional melt quenching method and characterized via spectroscopic techniques. The production of the strong electric field in the proximity of Dy3+ ion due to the localized surface plasmon (LSP) of embedded metallic NPs was found to improve the glass absorption properties. The effects of bimetallic NPs in changing the structure and absorption properties were found to be better than singly included metallic NP (either Ag or TiO2). This improvement in the absorption behavior was attributed to the combined LSP resonance (LSPR) effects of Ag and TiO2 NPs which transferred strong local electric field into the Dy3+ ions positioned in their vicinity. The UV-Vis-NIR spectra revealed six absorption bands centerted at 1690, 1283, 1097, 904, 800 and 755 nm which were allocated to the transition from 6H15/2 ground state to various excited states (6H11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2 and 6F3/2) of Dy3+ ion. Furthermore, the Raman spectra of such bimetallic NPs included glass system exhibited Raman peak shift accompanied by intensity variations when compared to the glass system with only one type of NPs incorporation. This enhancement in the Raman signal was ascribed to the LSPR mediated mechansim. The synthesized glass comporition was asserted to be prospective for devices.
Authors: Zhao Yong Ding, Bao Min Sun, Bing Hao Xu, Yuan Chao Liu, Yong Hong Guo
Abstract: Pyramid shaped pyrolysis flame is a new method for carbon nanotubes (CNTs) synthesis. Oxy-acetylene flame was used as the source of heat, CO as the source of carbon, iron pentacarbonyl (Fe(CO)5) as the source of catalyst precursor. Field emission scanning electron microscope(FE-SEM), High resolution transmission electron microscopy (HR-TEM) and Raman spectra were used to illustrate the results of experimental. In this experimental, coating substrate is not a special process, but a part of sampling. In the first 60s of sampling time, there were not CNTs synthesis, only the phase that substrate coats particles and temperature rise, so in this phase, catalyst particles formed. 304 stainless steel plate, monocrystalline silicon chip, and brass plate were used as substrates to synthesize CNTs. 304 stainless steel plate could gain straight, long, and uniform CNTs, monocrystalline silicon chip gain curly and short CNTS, while brass gain nothing but particles. Although single-walled carbon nanotubes (SWNTs) were not observed by SEM and TEM, it was successfully done by Raman spectra, in spite of the yield was small.
Authors: Tao Li, Ren Zhong Xue, Chun Mei Wang, Lei Su, Hai Yang Dai, Zhen Ping Chen
Abstract: The effects of Fe doping on the structure, electronic transport properties and Raman spectra of GdBa2Cu3-xFexO7-δ (x = 0.00-0.30) systems have been investigated. The analysis of X-ray diffraction patterns shows that the compound undergoes an Orthorhombic–Tetragonal (O-T) phase transition in the doping range of x = 0.05-0.10. The superconducting transition temperature Tc decreases with the increase of Fe doping level, whereas the superconducting transition width increases abruptly with O-T transition. We have discussed the Raman shifts and intensity of the five normal phonon peaks and some other peaks which result from the vibration of Cu(1) and O(1) oxygen for the Fe doped-samples. These investigations reveal that the electronic transport properties and Raman spectra of GdBa2Cu3-xFexO7-δ composites obviously depend on O-T transition induced by the Fe doping.
Authors: N. Bošnjaković, S. Uskoković-Marković, U.B. Mioč
Authors: Sandip V. Bhatt, M.P. Deshpande, Bindiya H. Soni, Nitya Garg, Sunil H. Chaki
Abstract: Thin film deposition of PbS is conveniently carried out by chemical reactions of lead acetate with thiourea at room temperature. Energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD), selected area electron diffraction patterns (SAED), UV-Vis-NIR spectrophotometer, Scanning Electron Microscopy (SEM), Atomic force microscopy (AFM), Photoluminescence (PL) and Raman spectroscopy techniques are used for characterizing thin films. EDAX spectra shows that no impurity is present and XRD pattern indicates face centered cubic structure of PbS thin films. The average crystallite size obtained using XRD is about 15nm calculated using Scherrer’s formula and that determined from Hall-Williamson plot was found to be 18nm. SAED patterns indicate that the deposited PbS thin films are polycrystalline in nature. Blue shift due to quantum confinement was seen from the UV-Vis-NIR absorption spectra of thin film in comparison with bulk PbS. The Photoluminescence spectra obtained for thin film with different excitation sources shows sharp emission peaks at 395nm and its intensity of photoluminescence increases with increasing the excitation wavelength. Raman spectroscopy of deposited thin film was used to study the optical phonon modes at an excitation wavelength of 488nm using (Ar+) laser beam.
Authors: V. Meenakshi, A. Sayeed, S.V. Subramanyam
Authors: Yang Yang, Di Yin, Xuan Wang, Fu Qiang Tian, Qing Quan Lei, Jing Shi, Rui Xiong
Abstract: Corona aging of 100CR polyimide (PI) film under bipolar pulse voltage was studied by using atomic force microscopy (AFM) and Confocal Raman microspectroscopy. AFM results show that the 100CR film near the breakdown hole is much rougher than the outside region. In the region away from the breakdown hole, no Raman shift is detected, but the intensity of all Raman peaks shows clearly decrease with the measuring region approaching more closely to the aging center. It is suggested that the damage of the PI film initiates from the surface in the presence of voids due to the partial discharge, and then gradually extends to interior, and these partial discharge cause progressive deterioration, and ultimately lead to the electrical breakdown of PI film with continuous aging.
Authors: C. Pakpum, N. Pasaja, P. Suanpoot, D. Boonyawan, P. Srisantithum, C. Silawatshananai, Thiraphat Vilaithong
Abstract: Diamond-like carbon (DLC) films were deposited on stainless steel disc substrates by plasma immersion ion implantation and deposition (PIII&D) technique. Ar, CH4 and C2H2 gas were used as the working gases and discharged by radio frequency at 13.56 MHz. During the implantation and deposition process the plasma discharge was monitored by optical emission spectroscopy in order to analyze the state of the chemical species presented in the plasma. Ion implantation (Vbias = -20 kV and –10 kV) process served to produce a graded interface between the DLC films and the substrate material. Deposition (Vbias = -5 kV) process using a gas mixture of C2H2/Ar with a ratio of 1:1. The structure information of the DLC films was evaluated by Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The composition of the DLC films and the thickness was measured by Rutherford backscattering spectrometry (RBS). The tribological properties were analyzed using a pin-on-disk tribometer and a microhardness tester, respectively. It was found that the DLC film was 0.8 μm thick with a hardness of 2.54 GPa and had good friction properties. Raman spectra appeared as G-band and D-band centered at 1550 cm-1 and 1418 cm-1, respectively. FTIR analysis observed the sp3 C=H2 asymmetric and sp2 C=C bond at 2928.73 cm-1 and 1667.10 cm-1 peak.
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