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Raman Scattering Spectra (raman + scattering_spectrum)
Selected AbstractsAnalysis of Phase Coexistence in Fe2O3 -Doped 0.2PZN,0.8PZT Ferroelectric Ceramics by Raman Scattering SpectraJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2006Man-Kang Zhu In this work, we suggested a method to evaluate quantitatively the effect of doping oxide on the phase coexistence of PbZr1,xTixO3 (PZT)-based ceramics through the analysis of the Raman scattering spectra. Theoretically, the degenerated T3u mode in the cubic phase of PZT will transform as A1(3) and E(4) modes in the tetragonal phase or as rhombohedral (R) modes in the rhombohedral phase below the Curie temperature, which set up the theoretical base to study the phase coexistence in ferroelectric materials. Through separation by fitting of the Raman bands, the shifts and intensities of different Raman vibration modes were determined. A calculation equation representing the phase coexistence was put forward based on the theoretical analysis of the degenerated T3u modes. The results showed that a turning point appears at the Fe2O3 addition of 0.3%. The variation in the electrical properties of the Fe2O3 -doped Pb(Zn1/3Nb2/3)O3 (PZN),PZT ceramics also affirmed the turning point of the phase evolution as the addition of Fe2O3. [source] Surface enhanced Raman scattering of trans-p-coumaric and syringic acidsJOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2009R. E. Clavijo Abstract The vibrational spectra of trans-p-coumaric acid (pCA) and syringic acid (SA) are discussed. The spectral fingerprints of the organic acids observed in the infrared and Raman spectra are assigned to fundamental vibrational wavenumbers supported by quantum chemical computations. The average surface-enhanced Raman scattering spectra of both acids have been obtained on silver colloidal solutions and the interpretation of the spectra is presented based on complementary Raman spectra and computational results for the silver salts. Copyright © 2009 John Wiley & Sons, Ltd. [source] Detailed analysis of single-molecule surface-enhanced resonance Raman scattering spectra of Rhodamine 6G obtained from isolated nano-aggregates of colloidal silverJOURNAL OF RAMAN SPECTROSCOPY, Issue 6-7 2005Slobodan Abstract Surface-enhanced resonant Raman scattering (SERRS) spectra of Rhodamine 6G (R6G) were acquired from single (aggregated) Ag colloidal particles that had been incubated with various amounts of R6G (0.1,125 nM). The spectra were investigated in detail and the evidence for a single-molecule-like response was found even for R6G:Ag particle ratios greatly exceeding equimolarity. After a thorough comparison with literature data, it is concluded that it is reasonable to expect a single-molecule-like response even for fairly ,high' R6G concentrations. A series of Raman images are shown and commented on with respect to bulk SERRS measurements. The problem of band assignment of single-molecule spectra of biological species is addressed. Copyright © 2005 John Wiley & Sons, Ltd. [source] Raman studies of cubic BC2N, a new superhard phaseJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2004H. W. Hubble Abstract UV and visible Raman scattering spectra of a new superhard phase, cubic BC2N, were measured for the first time. The Raman band at 1326 cm,1 was attributed to the longitudinal optical (LO) mode of cubic BC2N, whereas the transverse optic (TO) mode is missing in the spectra. Raman scattering was found to be a sensitive method for detecting new diamond-like BCN phases. Copyright © 2004 John Wiley & Sons, Ltd. [source] Sintering Diamond/Cemented Carbides by the Pulse Plasma Sintering MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2008Andrzej Michalski Under the conditions of thermodynamic instability, we produced dense sintered composites built of diamond particles (30 vol%) and a cemented carbide matrix. The composites were consolidated by high-current electric pulses at a temperature of about 1100°C and load of 75 MPa for 5 min. The diamond particles are strongly bound with the cemented carbide matrix, by a transition layer composed of a solid solution of carbon and tungsten in cobalt. No graphite precipitates were found in the sintered composites, as examined by microstructure observations, examinations of the phase composition, and an analysis of the Raman scattering spectra. The hardness of the diamond/cemented carbide was 23 GPa. [source] Analysis of Phase Coexistence in Fe2O3 -Doped 0.2PZN,0.8PZT Ferroelectric Ceramics by Raman Scattering SpectraJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2006Man-Kang Zhu In this work, we suggested a method to evaluate quantitatively the effect of doping oxide on the phase coexistence of PbZr1,xTixO3 (PZT)-based ceramics through the analysis of the Raman scattering spectra. Theoretically, the degenerated T3u mode in the cubic phase of PZT will transform as A1(3) and E(4) modes in the tetragonal phase or as rhombohedral (R) modes in the rhombohedral phase below the Curie temperature, which set up the theoretical base to study the phase coexistence in ferroelectric materials. Through separation by fitting of the Raman bands, the shifts and intensities of different Raman vibration modes were determined. A calculation equation representing the phase coexistence was put forward based on the theoretical analysis of the degenerated T3u modes. The results showed that a turning point appears at the Fe2O3 addition of 0.3%. The variation in the electrical properties of the Fe2O3 -doped Pb(Zn1/3Nb2/3)O3 (PZN),PZT ceramics also affirmed the turning point of the phase evolution as the addition of Fe2O3. [source] Polarized Raman scattering studies of nonpolar a -plane GaN films grown on r -plane sapphire substrates by MOCVDPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 15 2006Haiyong Gao Abstract Nonpolar (110) a -plane GaN thin films were grown on r -plane (102) sapphire substrates by low-pressure metal organic chemical vapor deposition (MOCVD). The stress characteristics of the a -plane GaN films were investigated by means of polarized Raman scattering spectra in backscattering configurations. The experimental results show that there are strong anisotropic in-plane stresses within the epitaxial a -plane GaN films by calculating the corresponding stress tensors. The temperature dependence of Raman scattering spectra was studied in the range from 100 K to 550 K. The measurements reveal that the Raman phonon frequencies decrease with increasing temperature. The temperature at which nonpolar a -plane GaN films are strain free is discussed. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photoluminescence from InGaN/GaN MQWs on sapphire and membranes fabricated by laser lift-offPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2004Tongjun Yu Abstract Photoluminescence and Raman scattering spectra of InGaN/GaN MQWs on sapphire and membranes free of substrate fabricated by laser lift-off have been studied. It is observed that photoluminescence peak of 850 °C annealed sample red-shifts from that of as grown sample, while in the case of membrane samples, the luminescence peak blue-shifts when annealed at 700 °C. In Raman scattering spectra, InGaN/GaN MQWs film without sapphire substrate has a lower E2 mode frequency (569.3 cm,1) than that of the films with substrate (570.8 cm,1), which indicates that compressive stress in the films releases partially when the sapphire substrate is taken off. It is believed that the piezoelectric field decrease leads to the blue-shift in luminescence spectra. Compared with the samples with sapphire substrate, the free-standing membranes showed blue-shift of luminescence peak after relatively low temperature annealing, because the piezoelectric field reduced more easily in the films without substrate. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Raman scattering spectra of CdS nanocrystals fabricated by a reverse micelle methodPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2009Aishi Yamamoto Abstract Raman scattering (RS) spectra of CdS nanocrystals (NCs) fabricated by a reverse micelle method were studied and were analysed using a phonon confinement model. One broad and red-shifted RS peak due to the LO phonon confined in CdS NCs was observed. The RS spectra were calculated using a phonon confinement model with the NC sizes estimated from the optical absorption spectra. The calculated RS spectra as suming that the NCs have the wurtzite structure reproduce the experimental spectra better than those assuming zincblende structure, which is consistent with the result of transmission electron microscope (TEM) observations. Our finding indicates that the crystal structure of the nanocrystal can be determined by the analyses of Raman scattering spectral shape. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Raman spectra and elastic properties of KPb2Cl5 crystalsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2004A. N. Vtyurin Abstract Raman scattering spectra and elastic constants of KPb2Cl5 crystals have been studied. The results obtained are interpreted in terms of the ab initio lattice dynamics model taking into account multipole moments of ionic electron envelopes. The experimental results have been found to be in good agreement with numerical simulation; the narrow phonon spectra are shown to be due to a considerable contribution of heavy cations into the eigenvectors of the higher frequency lattice modes. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Surface enhanced Raman scattering of a lipid Langmuir monolayer at the air,water interfaceBIOPOLYMERS, Issue 1-2 2004C. Mangeney Abstract Surface enhanced Raman spectra were recorded from a phospholipid monolayer directly at the air,water interface. We used an organized monolayer of negatively charged tetramyristoyl cardiolipins as a template for the electrochemical generation of silver deposits. This two-dimensional electrodeposition of silver under potentiostatic control was the substrate for enhancement of Raman spectra. We report the optimized conditions for the Raman enhancement, the microscopic observations of the deposits, and their characterization by atomic force microscopy. Laser excitation at 514.5 nm leads to intense and reproducible surface enhanced Raman scattering spectra recorded in situ from one monolayer of cardiolipin, using 0.5 mol % of 10N nonyl acridine orange or 5 mol % of acridine in the film, and demonstrates the possibility of estimating the pH at the metal/phospholipidic film interface. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004 [source] | |||||||||||||