bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polarization measurements in near‐infrared—fourier transform spectroscopy
Authors: Hoffmann Andreas , Keller Stefan , Schrader Bernhard , Ferwerda Roeland , Van Der Maas John H. 
Published: May 2005

AbstractIn principle, Raman measurements provide information about vibrational frequencies and intensities. Working with polarized light provides additional information about the Raman scattering tensor components. The special conditions relating to the near‐infrared‐Fourier transform (NIR‐FT) Raman technique may preclude adaptation of some of the techniques employed for measurements with linear polarized light in ‘classical’ Raman spectroscopy in the visible range. The experimental conditions for measurements of depolarization ratios of liquids (benzene, mesitylene, p‐xylene and carbon tetrachloride) using different experimental geometries with an NIR‐FT‐Raman spectrometer were elucidated. The FT technique allows the rapid and simple determination of depolarization ratios with a quality sufficient to assign the bands to totally or non‐totally symmetric species. The possibility of determining the orientation of molecules in non‐crystalline solids is also demonstrated. Finally, the feasibility of measuring the different components of the Raman scattering tensor of a single crystal of sodium chlorate is considered.
Rotational isomers of methyl trans‐cinnamate: A Raman study
Authors: Faria M. Dulce G. , Teixeira‐Dias J. J. C. , Fausto R. 
Published: May 2005

AbstractThe Raman and infrared spectra of methyl trans‐cinnamate were measured as a function of temperature in the liquid and solid phases. The temperature dependence of the band intensities established the presence of two conformers in the liquid phase (the s‐cis and s‐trans forms, with CCCO dihedral angles equal to 0° and 180°, respectively; ΔH(s‐trans)‐(s‐cis) = 3.43 ± 0.84 kJ mol−1) and led to the conclusion that the thermodynamically most stable s‐cis form is the only form present in the solid.
Bond length‐Raman frequency correlations in borate crystals
Authors: Chryssikos G. D. 
Published: May 2005

AbstractCorrelations are established between the structural data provided by x‐ray diffraction and Raman spectroscopy on borate crystals. A linear relationship is found to be adequate to describe the bond length‐stretching frequency correlations in nine meta‐, pyro‐ and ortho‐borate crystals consisting solely of triangular borate arrangements. This result allows bond length and strength predictions for newly synthesized compounds to be made, as well as assisting in the elucidation of the influence of borate tetrahedra on the πp bonding of BO− ‘probes’ in borate crystals. A wide field of applications in the structural study of borate glasses is introduced.
Hydrogen bonding and the liquid‐to‐glass transition in propan‐1‐ and ‐2‐ol at high pressures
Authors: Yenice K. M. , Reed M. D. , Lee S. A. , Chang C. S. 
Published: May 2005

AbstractThe pressure dependence of the vibrational modes of propan‐1‐ and ‐2‐ol was measured by Raman spectroscopy up to 8 GPa at 300 K. Changes in the observed vibrational spectra indicate that the samples undergo a liquid‐to‐glass transition at about 4.5 GPa for propan‐2‐ol and about 5.5 GPa for propan‐1‐ol. The frequency of the O‐H stretching mode (a probe of the degree of hydrogen bonding) was found to decrease at a rate of ca −28 cm−1 GPa−1 for both propan‐1‐ and ‐2‐ol.
Surface electric field‐induced Raman spectroscopy from adsorbate and substrate modes
Authors: Krasser W. , Kojnok J. , Geurts J. 
Published: May 2005

AbstractRaman spectroscopy due to electric fields at surfaces, which manifests itself as surface‐enhanced Raman scattering (SERS) from adsorbate modes, and as electric field‐induced Raman scattering (EFIRS) from substrate modes, is discussed. In SERS experiments with benzene adsorbed on small Ni/SiO2 and Pt/SiO2 clusters, using exciting radiation of different wavelengths, we observed not only very strong peaks of the normally Raman active vibrational modes but also normally infrared‐active and some inactive modes. Although the frequencies of the modes are only slightly shifted with respect to liquid benzene, the relative intensites of the Raman lines are considerably changed and in addition they are dependent on the excitation wavelength. The observation of metal‐carbon vibrations indicates a strong interaction between the adsorbate and the metal atoms. Therefore, in addition to the electric field, a metal‐molecule electronic charge transfer may be responsible for the enhancement mechanism.EFIRS is based on the symmetry‐forbidden scattering from the longitudinal optical (LO) substrate phonon. It allows the detection of the static electric field in the surface region of semiconductor substrates, which originates from electronic band bending. By EFIRS the band bending can be monitored at surfaces and interfaces for coverages from submonolayer up to more than 100 monolayers, depending on the overlayer material. Here, the Sb/GaAs(110) interface is treated as an example. Considerable band bending dynamics is observed for overlayer thicknesses up to 100 monolayers. Simultaneous analysis of the overlayer structure by Raman scattering from the Sb vibration modes allows the interpretation of the band bending dynamics.
Surface‐enhanced Raman scattering of o‐mercaptobenzoic acid in silver sol
Authors: Lee Sang Bok , Kim Kwan , Kim Myung Soo 
Published: May 2005

AbstractSurface‐enhanced Raman scattering of o‐mercaptobenzoic acid (OMBA) in silver sol was investigated. At neutral and basic pH OMBA adsorbed dissociatively on the silver surface via both its sulphur and the carboxylate group and existed as sulphidobenzoate. As the sol solution was acidified, the carboxylate group in o‐sulphidobenzoate was protonated on the silver surface while the thiolate group was present as a deprotonated ionic form. At pH 1.2, OMBA adsorbed on the silver surface exclusively via its sulphur atom as o‐sulphidobenzoic acid. As the bulk concentration of OMBA increased, the effect of favourable surface packing appeared to be more important than the pH effect in determining the surface orientation of adsorbed OMBA.
Interference effects in Raman scattering from overlayers on metals
Authors: Lenac Z. , Tomaš M. S. 
Published: May 2005

AbstractA general theoretical description of Raman scattering in layered systems is presented and applied to Raman scattering from overlayers on metals. The effects of interferences and metal thickness in Raman scattering from such systems are discussed in detail. It is shown that for a thick overlayer the intensities of Raman signals decrease with decreasing metal thickness; however, for a thin overlayer they may also increase, depending on the polarization of incident and scattered light and the scattering geometry chosen. The technique of interference‐enhanced Raman scattering is also reconsidered theoretically. It is suggested that greatly enhanced signals could be obtained in those configurations in which thin sample films are embedded at prescribed positions in a transparent dielectric between a reflecting metal and a high‐index superstrate (prism).
Raman, pre‐resonance Raman and electronic spectra of iron(II) saccharinate
Authors: Jubert A. H. , Diez R. Pis , Etcheverry S. B. , Baran E. J. 
Published: May 2005

AbstractThe Raman spectrum of solid [Fe(Sac)2 (H2O4)] · 2H2O was recorded and assigned. Some comparisons with the spectra of the related copper(II) and nickel(II) complexes were also made. The excitation profiles of the vibrational modes that show pre‐resonance on excitation with laser lines within the electronic bands are reported. On this basis, and with the aid of a semi‐empirical extended Hückel MO calculation, the assignment of the metal—ligand vibrations and the interpretation of the electronic spectrum could be reinforced.
Effect of hydrophobic environment on the resonance Raman spectra of tryptophan residues in proteins
Authors: Efremov R. G. , Feofanov A. V. , Nabiev I. R. 
Published: May 2005

AbstractThe influence of environmental hydrophobicity on the UV resonance Raman spectra of tryptophan residues in proteins was studied using laser excitation at 230 nm. An increase in hydrophobicity was found to enhance the resonance Raman cross‐sections without significant changes in the frequencies and relative intensities of the Trp vibrational modes. It was shown that this effect is strong enough to be used for studies of the tryptophanyl micro‐environment in proteins. The resonance Raman cross‐section of tryptophanyl increases relative to that of N‐Ac‐Trpethyl ester by factors of 2, 3, 3, 4.4 and 1.6 for melittin, melittin incorporated into liposomes, azurin, bacteriorhodopsin and lysozyme, respectively.
Micro‐Raman spectroscopy of carbon cluster composites
Authors: Grigoryan L. S. , Bist H. D. , Sathaiah S. , Sharma S. V. , Clara H. , Majumdar A. K. 
Published: May 2005

AbstractMicro‐Raman spectra were obtained with three different films and also with amorphous carbon and highly oriented pyrolytic graphite samples for comparison. The spectra of the crystallites are similar, differing mainly in frequency and line width of the major line with the position varying from 1566 to 1578 cm−1. The corresponding line for the pyrolytic graphite is at 1581 cm−1. Another difference is related to the strength of two broad background features at ca. 1350 and 1595 cm−1, evidently due to a certain amount of amorphous carbon within the spot area. In general, the spectra of the crystallites are similar to that of C70 films reported earlier.
Raman intensity of lattice vibrations in β‐Ba(OH)2 · H2O
Authors: Kanesaka Isao , Ikeda Satoshi 
Published: May 2005

AbstractIt is shown that the Raman intensity of translational lattice vibrations in β‐Ba(OH)2 · H2O can be explained satisfactorily in terms of bond polarizability parameters obtained from the atom dipole interaction model. The analysis was carried out on the basis of two models. Model A used only bond polarizability parameters for bond stretchings. Model B used bond polarizability parameters for bond stretchings and bond rotations, where the parameters were obtained using only three atomic or ionic polarizabilities. Model B resulted in excellent agreement with observed spectra.
Vibrational Raman spectroscopic studies of calcium oxalate monohydrate and dihydrate in lichen encrustations on renaissance frescoes
Authors: Edwards H. G. M. , Farwell D. W. , Jenkins R. , Seaward M. R. D. 
Published: May 2005

AbstractVibrational Raman spectroscopic studies of the monohydrate and dihydrate of calcium oxalate were undertaken in order to characterize these compounds in lichen encrustations which cause biodeterioration of Renaissance frescoes. Spectroscopic data from the CaC2O4 · D2O species provided an aid to the vibrational assignments and indicated that amendment to some literature assignments was necessary. Application of the results to samples of the lichen Dirina massiliensis forma sorediata encrusting certain Italian Renaissance frescoes demonstrated that it is possible to identify the monohydrate and dihydrate of calcium oxalate at a microscopic level.
UV resonance Raman spectroscopy using a quasi–continuous—wave laser developed as an industrial analytical technique
Authors: Williams K. P. J. , Klenerman D. 
Published: May 2005

AbstractA resonance Raman method was developed for the study of a wide range of materials possessing UV chromophores with high sensitivity. The experimental arrangement, utilizing a low peak power yet high average power quasicontinuous‐wave laser source, permits the study of both liquid and, for the first time, solid samples. Evidence for laser‐induced sample degradation was observed from low levels of solid polycyclic aromatics dispersed in potassium chloride, but this was largely overcome by sample spinning. In addition, it was found that the Raman spectrum of individual components in a complex mixture can be selectively enhanced by a judicious choice of laser wavelength. Polyethylene and poly(vinyl chloride) were investigated and evidence for unsaturation was detected from both systems. This is attributed to the resonance enhancement of unsaturated moieties contained within the polymer.
Raman scattering study of a new laser crystal: LiCaAlF6
Authors: Daniel P. , Gesland J. Y. , Rousseau M. 
Published: May 2005

AbstractThe Raman spectra of the trigonal LiCaAlF6 Crystal were recorded at room temperature and 10 K. Three A1g and eight Eg Raman lines are expected according to group theory. Based on the polarized Raman spectra, symmetry assignments were made for the 11 predicted Raman‐active phonon modes. Throughout the temperature range studied, no drastic evolution of the Raman spectra was observed, which suggests that there is no structural phase transition in LiCaAlF6. Analysis of the Raman spectra was made by comparison with previous studies of several crystal fluorides such as Li2ZrF6.
Vibrational spectrum, conformational stability, barriers to internal rotation, r0 structural parameters and ab initio calculations of bromomethyl methyl ether
Authors: van der Veken B. J. , Guirgis G. A. , Liu Jian , Durig J. R. 
Published: May 2005

AbstractThe Raman and far‐infrared spectra at a resolution of 0.10 cm−1 of gaseous bromomethyl methyl ether, BrCH2OCH3, and three of its deuterium isotopes, d2, d3 and d5, were recorded in the 350‐50 cm−1 region. The fundamental asymmetric torsional and methyl torsional modes for the d0 molecule are extensively mixed and were observed at 176 and 130 cm−1, respectively, for the stable gauche conformer with each mode having excited states falling to lower frequency. An estimate is given for the potential function governing the asymmetric rotation. On the basis of a one‐dimensional model the barrier to internal rotation of the methyl moiety is determined to be 549 ± 8 cm−1 (1.57 ± 0.02 kcal mol−1). A complete assignment of the vibrational fundamentals for all four isotopic species observed from the infrared (3500–50 cm−1) spectra of the gas and solid and Raman (3200–10 cm−1) spectra of the gas, liquid and solid is proposed. All of these data are compared with the corresponding quantities obtained from ab initio Hartree‐Fock gradient calculations employing the STO‐3G* basis set. Additionally, complete r0 geometries were determined from the combined previously reported microwave data and CH distances determined from infrared studies along with carbon—hydrogen angles transferred from the corresponding chloride. The heavy atom structural parameters (distance in Å, angles in degrees) are r(C1Br) = 1.996 ± 0.005; r(C1O)=1.359 ± 0.005; r(C2O) = 1.433 ± BrCO = 113.7 ± 0.3; ∢ C1OC2 = 113.5 ± 0.3 and dih BrC1OC2 = 70.9 ± 0.3. All of these results are discussed and compared with the corresponding quantities obtained for some similar molecules.
Raman spectroscopic study of complex formation between phenol and propionitrile
Authors: Ng J. C. F. , Park Y. S. , Shurvell H. F. 
Published: May 2005

AbstractThe nitrile stretching region of binary solutions of phenol in propionitrile has been studied by means of Raman spectroscopy. The number of independently varying spectral components in this region was determined by Factor Analysis to be two. The results of Factor Analysis were supported by the observation of a pseudo‐isosbestic point. The band envelope was fitted with Lorentzian—Gaussian product functions using a non‐linear least squares procedure. The results indicate the formation of a 1:1 complex. Equilibrium constants calculated for the complex formation reaction showed a strong concentration dependence.
Fourier transform surface‐enhanced Raman scattering of flavins in silver colloid using Nd: YAG 1064 nm excitation
Authors: Yoo Hee‐Soo , Lee Nam‐Soo , Hanazaki Ichiro 
Published: May 2005

AbstractFourier transform surface–enhanced Raman spectra of 1 × 10−6 M lumiflavin and riboflavin were obtained in silver coloid (pH 7.2) using 1064 nm continuous‐wave laser excitation. These Raman spectra imply that the flavin ring III moiety is coadsorbed on the colloidal silver metal surface through oxygens of C(2)O and C(4)O with the colloid preparation components, the EDTA anion or the NO3− ion.
Raman study of a phase transition in solid chlorodifluoromethane
Authors: Lefebvre J. H. , Anderson A. 
Published: May 2005

AbstractRaman spectra of solid chlorodifluoromethane at temperatures between 20 and 80 K in both the lattice and internal mode regions are reported. Evidence of a solid‐state phase transition at 60 ± 5 K is presented. In both phases, the multiplet structure of the internal fundamentals is shown to originate from crystal field rather than isotopic effects for most modes, which indicates that both phases are ordered with fairly large unit cells and that the transition is therefore of a displacive type.
Raman, pre‐resonance Raman and electronic spectra of the anion [VO2Q2]− (Q = 8‐hydroxyquinolinate)
Authors: Jubert A. H. , Baro A. C. Gonzalez , Diez R. Pis , Baran E. J. 
Published: May 2005

AbstractThe Raman spectrum of Na[VO2Q2] was recorded and assigned by comparison with related species. The excitation profiles of the vibrational modes that show pre‐resonance on excitation using laser radiation within the electronic bands are reported and three different types of profiles could be found. The electronic spectrum of the anion was also recorded and interpreted with the aid of a semi‐empirical MO calculation. This calculation, together with the results of the pre‐resonance experiments, also reinforced some of the vibrational assignments.
Normal Raman and surface‐enhanced Raman scattering (SERS) spectra of some fungicides and related chemical compounds
Authors: Narayanan V. Anantha , Begun George M. , Stokes David L. , Sutherland W. Scott , Vo‐Dinh Tuan 
Published: May 2005

AbstractSurface‐enhanced Raman scattering (SERS) spectra of Thiram (C6H12N2S4) and Ferbam (C9H18N3S6Fe); and normal Raman scattering (NRS) spectra of Thiram and Metam‐Sodium (C2H4NNaS2) were investigated. The SERS spectra of the two compounds and NRS spectrum of Metam‐Sodium were recorded for the first time. The SERS signals useful for trace analysis of these fungicides are identified. The spectral features of these compounds are discussed and compared with the previous data. The importance of SERS analyses to ensure the environmentally safe use of such compounds is discussed.
High‐pressure Raman study of fullerite C60
Authors: Jeon Seung‐Joon , Kim Dongho , Kim Seong Keun , Jeon Il Cheol 
Published: May 2005

AbstractHigh‐pressure Raman spectra of fullerite, a solid form of C60, were measured at pressures up to 4 GPa and room temperature. A change of slope (dv/dP) of the frequency‐pressure plots for the Ag pentagonal pinch mode and the Ag breathing mode was observed at 1.3 GPa, where a solid‐solid phase transition might occur. The phase transition was observed to be irreversible. The pressure dependence of the Raman mode frequency and the phase transition are discussed in terms of an orientational ordering transition in fullerite.
Raman spectroscopy of graphite in cast iron
Authors: Hirlimann C. , Jouanne M. , Forrières C. 
Published: May 2005

AbstractThe Raman scattering spectra of carbon inclusions found in two cast iron samples were studied. From the observed spectra it was deduced that this carbon is made of good‐quality microcrystals, 5 nm in size, in the planes of the threefold coordinated carbon.
Surface‐enhanced Raman spectroscopy of ellipticine, 2‐N‐methylellipticinium and their complexes with DNA
Authors: Aubard J. , Schwaller M. A. , Pantigny J. , Marsault J. P. , Lévi G. 
Published: May 2005

AbstractSurface‐enhanced Raman spectroscopy (SERS) in silver colloidal solutions of ellipticine, 2‐N‐methylellipticinium and their complexes with DNA were investigated. On varying the pH of silver sols, large spectral changes are observed in the SER spectra of ellipticine which are related to the reversible transformation between the neutral and protonated forms. From intensity measurements the protonation pK of ellipticine absorbed on silver collo ds was estimated (ca. 7.5). This value is very close to that previously obtained in a pure aqueous medium from UV‐visible absorption and fluorescence data. This indicates that the interstion of ellipticine with the silver surface does not perturb the protonation equilibrium at N‐2. The intensity changes observed in the SER spectrum of the ellipticine‐DNA complex at pH 8.5 are interpreted as arising from a shift of the protonation equilibrium in the presence of DNA (pKa ≈ 8.6) and not from perturbations induced by intercalation of the drug between base pairs. The results of this study suggest that adsorption of ellipticine (and the ellipticinium derivative) on silver colloids takes place through the indole moiety with the chromophore plane perpendicular to the silver surface.
Radical polymerization of methyl methacrylate in solution monitored and studied by Raman spectroscopy
Authors: Damoun S. , Papin R. , Ripault G. , Rousseau M. , Rabadeux J. C. , Durand D. 
Published: May 2005

AbstractRaman spectroscopy was used to investigate the kinetics of the free‐radical polymerization of methyl methacrylate in toluene, initiated with azobisisobutyronitrile at 70°C. The decrease in the intensity of the 1636 cm−1 CC stretching band compared with a solvent band as an internal standard allows an accurate determination of the rate of conversion of monomers to polymeric chains. A careful quantitative study of the evolution of the CO stretch band profile, interpreted in terms of intra‐chain dipole‐dipole interactions, gives a similar dependence for the conversion.
Vibrational spectra of tris(methylammonium) cyclotriphosphate
Authors: George Bini Lizbeth , Joe I. Hubert , Aruldhas G. 
Published: May 2005

AbstractIR and Raman spectra of (CH3NH3)3P3O9 were recorded and analysed. The vibrational bands due to P3O and (CH3NH3)+ groups are identified. From the spectral analysis, it is inferred that the P3O ion has a ring structure in the compound. Hydrogen bonds of moderate strength are observed between the external oxygen atoms of P3O and NH3+ groups.
Low‐frequency Raman spectra of dehydrated zeolites using dispersive and Fourier‐transform techniques
Authors: Boulet Hélène , Brémard Claude , Le Maire Marielle 
Published: May 2005

AbstractThe low‐frequency Raman spectra of dehydrated faujasite‐type zeolites using the dispersive technique, provides evidence for the translational motions of the extra‐framework cations in addition to the framework vibrational motions.