bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman phonon spectroscopic study of phase transition in o‐aminobenzoic acid crystal (II)
Authors: Chakrabarti Subhasis , Sarkar Uttam K. , Misra T. N. 
Published: May 2005

AbstractRaman phonon spectroscopy in the 10–150 cm−1 shift range was used to study the phase transition in an o‐aminobenzoic acid crystal (II). At 77 K, twelve distinct phonon modes are observed whereas at 300 K the spectrum shows ten phonon bands. The temperature dependence of the phonon frequencies and band widths suggests that the crystal goes through a phase transition at ca. 200 K. The temperature dependence of the internal modes predicts that the phase transition is associated with some structural change in the phenyl ring.
Use of the laser Raman microprobe for discrimination amongst feldspar minerals
Authors: Mernagh T. P. 
Published: May 2005

AbstractRaman spectroscopy was used to distinguish the individual members of the two feldspar subgroups. All feldspars were found to exhibit a characteristic, intense line between 500 and 515 cm−1 which is attributed to a mixed SiOSi (or SiOAl) bending/stretching mode. However, discrimination between the related members within each subgroup relies on the change in frequencies and band widths which occur in the external lattice modes and in the SiO stretching region. Spectra were recorded from single crystals and powders and demonstrate that the laser Raman microprobe can provide non‐destructive and rapid identification of feldspars on the microscopic scale.
On the non‐zero depolarization ratio in totally symmetric modes of molecules with cubic point group symmetry
Authors: Hecht Lutz 
Published: May 2005

AbstractImperfections in the incident laser beam polarization modulation technique in linear polarization Raman measurements are calculated on the basis of the Stokes‐Mueller formalism. An equation for the depolarization ratio in totally symmetric Raman bands of molecules with cubic point group symmetry is derived, yielding a depolarization ratio of ρ′obs. = 1.38 × 10−3 for the ν1 CCl stretching vibration in the C35Cl4 species. The comparison of the computed depolarization ratio with the smallest experimental value reported so far, ρobs. = 2.30 × 10−3, implies that recent attempts to explain the observation of a non‐zero depolarization ratio for the ν1 mode in liquid CCl4 by intermolecular interactions present in the condensed phase are less relevant than suggested.
Temperature‐dependent Raman scattering studies in ferroelastic LiCsSO4
Authors: Morell G. , Devanarayanan S. , Katiyar R. S. 
Published: May 2005

AbstractTemperature‐dependent first‐order Raman scattering studies in the range 30–290 K were carried out in LiCsSO4 in order to investigate its phonon spectra in relation to the phase transitions in the crystal. Complete spectra were obtained for the z(xx)y and z(xz)y geometries. A careful analysis of the spectra shows that both the low‐ and high‐energy Raman modes exhibit variations either in frequency or intensity or both with temperature of the crystal, indicating that the D2k normal phase undergoes a transition at the Ti (202 K) and one to the commensurate phase at ca 160 K (Tc). Below the Tc, in the C2ν phase, the lattice mode at 44 cm−1 was observed to be a soft phonon with its frequency decreasing to 32 cm−1 at 30 K, indicating the possibility of a new structural phase transition of unlocking type in the crystal at a temperature Tu below 20 K. Another observation is the oscillating behaviour of Rayleigh scattering near the phase transition at the Ti.
Polarized micro‐Raman and Fourier transform infrared spectra of L‐glutamic acid
Authors: Dhamelincourt P. , Ramírez F. J. 
Published: May 2005

AbstractThe infrared and polarized Raman spectra of the amino acid L‐glutamic acid in the crystalline state have been recorded and measured. The data obtained have been used to propose a general assignment of the vibrational fundamentals on the intensity changes observed in the polarized Raman spectra and correlations with frequencies assigned in other amino acids and related molecules.
Polarized Raman and IR spectra of magnesium diammonium bis(hydrogen orthophosphate) tetrahydrate
Authors: Jayakumar V. S. , Rajagopal P. , Aruldhas G. 
Published: May 2005

AbstractThe polarized Raman and IR spectra of Mg(NH4)2(HPO4)2·4H2O and its partially deuterated polycrystalline sample were recorded and analysed. The presence of bands characteristic of HPO2−4 and DPO2−4 ions are interpreted in terms of the proton polarizabilities of the HPO2−4 and jDPO2−4 ions. The ammonium ion is free to rotate in the crystal and crystallographically distinct NH4+ ions exist. Hydrogen bonding of different groups is also discussed.
Surfactant‐aided surface enhanced Raman scattering of Ni(II) tetrasulphonate phthalocyanine in silver sol
Authors: Ha Jong‐Seo , Yoon Minjoong , Lee Minyung , Jang Du‐Jeon , Kim Dongho 
Published: May 2005

AbstractSurface enhanced Raman scattering (SERS) has been used to investigate the structure, surface reaction and enhancement mechanism of adsorbed molecules on metal surfaces. However, a major limitation has been having to choose the molecules with functional groups capable of adsorbing onto metal surfaces. We report here SERS of Ni(II) tetrasulphonate phthalocyanine (Ni(II)PCS) as a result of introducing cationic surfactants like CTAB or CTAC. Ni(II)PCS does not adsorb onto a silver surface by itself and consequently does not show any SERS effect. The cationic surfactants employed here have functional groups to adsorb onto a silver surface and simultaneously interact with anionic sulphonate groups of Ni(II)PCS. Surfactant‐aided SERS would expand the range of SERS application to molecules which are not able to adsorb onto metal surfaces by themselves.
Line widths in the pure rotational Raman spectra of hydrogen and deuterium self‐broadened and broadened by foreign gases
Authors: Edwards H. G. M. , Long D. A. , Sherwood G. 
Published: May 2005

AbstractThe pressure‐broadening coefficients for the self‐broadened S0(0), S0(1) and S0(2) pure rotational Raman lines of hydrogen and the S0(0) to S0(4) lines of deuterium were determined experimentally over the pressure range 1–100 bar and the temperature range 90–375 K. Broadening coefficients were also determined for the same lines in hydrogen and deuterium perturbed by helium, argon, oxygen, nitrogen, carbon monoxide and hydrogen chloride over the pressure range 2–100 bar, with a partial pressure of the host gas of 1 bar and a temperature of 293 K. In addition, the S0(0) pure rotational line of deuterium broadened by carbon monoxide and nitrogen was studied over the same pressure range and a temperature range of 100–293 K. The results are discussed and compared with those of previous studies in the literature.
Polarized Raman spectra of ktioaso4 and isomorphic nonlinear‐optical crystals
Authors: Watson G. H. 
Published: May 2005

AbstractPotassium titanyl orthorarsenate KTiOAsO4 (KTA) was studied by polarized Raman spectroscopy at room temperature. Group assignments were made by comparison with Raman spectra obtained from the well known isomorphs KTiOPO4 (KTP) and RbTiOPO4. The Raman features associated with vibrations of TiO bonds provide most of the scattered intensity. Splittings arising from occupation of two distinct sites by each of the AsO4 and TiO6 groups are observed. Additional evidence for a smaller distortion of the TiO6 group in KTA than in KTP is also present in the Raman spectra.
Interactions of cytidine derivatives with metals as revealed by surface‐enhanced Raman spectroscopy
Authors: Sánchez‐Cortés S. , Molina M. , García‐Ramos J. V. , Carmona P. 
Published: May 2005

AbstractSurface‐enhanced Raman spectra of cytidine and cytidine 5′‐monophosphate adsorbed on copper and silver colloids were investigated. As an aid to the interpretation with regard to the metal‐adsorbate binding sites, the normal Raman spectra of the complexes of these substances with the metal ions were also obtained. The adsorption of the cytosine moiety in these substances occurs preferentially through the carbonyl bond, the pyrimidine ring adopting a non‐planar orientation on the surface. However, in the complexes involving the metal ions the N‐3 position is found to be the site through which the base interacts with these metals. The ribofuranose ring does not seem to participate significantly in the interaction of these substances with copper and silver in either the colloidal or ionic states.
Polarized infrared and Raman spectra of urea—phosphoric acid and urea—arsenic acid single crystals
Authors: Ilczyszyn M. M. , Ratajczak H. , Barnes A. J. 
Published: May 2005

AbstractThe polarized infrared and Raman spectra of single crystals of urea—phosphoric acid, (NH2)2CO · H3PO4, its deuterated analogue, (ND2)2CO · D3PO4, and urea—arsenic acid, (NH2)2CO · H3AsO4, were measured. The results obtained are discussed on the basis of the crystal structure and the selection rules. Characteristic spectral features due to hydrogen bond vibrational modes were identified, from their polarization behaviour, as arising from the very short, almost symmetrical O …︁ H …︁ O hydrogen bond connecting the urea and phosphoric (or arsenic) acid molecules and from two other strong OH …︁ O hydrogen bonds, linking different adducts.
Vibrational spectroscopic study of the three solid phases of bicyclo[2.2.2]octene
Authors: Kawai Nancy T. , Butler Ian S. , Gilson Denis F. R. 
Published: May 2005

AbstractThe three solid phases of bicyclo [2.2.2] oct‐2‐ene were characterized by vibrational spectroscopy at low temperatures and high pressures. Bicyclooctene undergoes a phase transition at 176 K on cooling (phase I → phase II) and then another at ca 95 K (phase II → phase III). On compression at room temperature, these same transitions occur at 7.9 ± 1.0 kbar and ca. 15 kbar. The low‐frequency Raman spectra show that phase I is isotropically disordered, whereas phase II is anisotropically disordered. The crystal structure of phase II is, however, similar to that of phase III, and is suggested to be tetragonal.
Raman spectra of Pb1–3x Bi2x MoO4 (x ⩽ 0.06) and their 18O‐substituted systems
Authors: Kanesaka Isao , Kirishiki Masaru , Matsuura Ikuya 
Published: May 2005

AbstractA new band at 896 cm−1 is ascribed to a local mode, v1, due to a molybdate ion occupying a cation vacancy. Local modes for v3 and v4 were also found at ca. 800 and 397 cm−1, respectively. The relative intensity for translational modes at 71 and 59 cm−1 varied considerably with x. This was explained in terms of a decrease in primitive cells with two Pb2+ ions. The band decomposition was carried out for the v1 region in 18O‐substituted systems. The equilibrium distribution for isotopic species, [Mo16O4‐n18On]2− (n=0‐4). was found approximately in the system with x = 0.01 after annealing, whereas the discrepancy between the observed and equilibrium distributions increased with increase in x. These observations show that a molybdate ion interacting strongly with a Bi3+ ion and a cation vacancy is inactive for 18O‐substitution.
Raman study of the phase transition in CsSnCl3
Authors: Kuok M. H. 
Published: May 2005

AbstractThe polarized Raman spectrum of CsSnCl3 single crystals was studied as a function of temperature between 10 and 400 K. When heated above 385 K the crystals transform from the monoclinic to the cubic perovskite phase, and the Raman data suggest that the phase transition is first order. No soft mode was observed. No further signs of any structural phase transitions were found on cooling the crystals to 10 K. Several Raman bands were assigned to the correlation‐field split components of the funadmental vibrations of the pyramidal SnCl ion.
Raman and infrared spectra, conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment for vinyl fluoroformate
Authors: Durig J. R. , Lin Jie , van der Veken B. J. 
Published: May 2005

AbstractThe Raman spectra (3200—10 cm−1) and infrared spectra (3500—50 cm−1) of vinyl fluoroformate, H2CCHOC(O)F, were recorded for both the gas and solid. Additionally, the Raman spectrum of the liquid was recorded and depolarization ratios were obtained. These data have been interpreted on the basis that the only stable conformation present at ambient temperature is the trans‐trans, where the first trans refers to the vinyl moiety relative to the OCFO bond and the second trans to the CF bond relative to the CO bond. Anharmonic rigid asymmetric top calculations were used to predict the CO and CC stretch infrared vapor‐phase contours for the trans‐trans and the cis‐trans conformers. For both conformers, the predicted CO stretch contour agrees with the experimentally observed contour. For the CC stretch, only the contour predicted for the trans‐trans conformer reproduces the experimental contour. From the far‐infrared spectrum of the vapor obtained at a resolution of 0.1 cm−1, the methoxy and O‐vinyl torsional fundamentals have been observed at 153 and 63 cm−1, respectively. The structure, barrier to internal rotation and vibrational frequencies were also determined from ab initio Hartree‐Fock gradient calculations using both the 3—21G and 6—31G* basis sets. These results are compared with theos obtained experimentally and to similar quantities for some related molecules.
Raman and hyper‐Raman tensors for point groups with eightfold rotation axes
Authors: Jiang Yi‐Jian , Liao Li‐Ji , Chen Gang , Zhang Peng‐Xiang 
Published: May 2005

AbstractUsing a new method, the Raman and hyper‐Raman tensors for the point groups 8 (C8), 8 (S8), 8/m (C8h), 8mm (C8ν), 822 (D8) and 8/mmm (D8h) have been tabulated.
Some comments on ‘quenching of stimulated Raman scattering by two‐photon absorption in fuels’
Authors: Jones W. Jeremy 
Published: May 2005

AbstractA recent paper by Golombok et al. in this Journal provides an explanation for the appearance in stimulated Raman scattering from certain aromatic liquids of oscillation on many Raman modes in place of the single Raman mode that generally dominates such spectra; this explanation is based on two‐photon absorption of the resulting Raman radiation. It is suggested in this paper that this process, although undoubtedly significant, is not the dominant process in suppressing completely oscillation on certain strong, sharp Raman transitions which would be expected to dominate the spectra. Of greater significance in suppressing such oscillations will be sum‐photon absorption with one photon being absorbed from each of the incident laser and the Stokes‐shifted Raman radiation. Calculated growth curves of the Raman radiation generated show that this process has the correct functional dependence to prevent Raman oscillation totally whereas two‐photon absorption of the Raman radiation created can only limit, but not totally suppress, the growth of the first Stokes wave.
Vibrational spectra and conformations of 1, 4‐dibromobut‐2‐yne and 1,4‐diiodobut‐2‐yne
Authors: Karlsson A. , Bauza G. D. , Klaeboe P. , Nielsen C. J. , Sülzle D. 
Published: May 2005

AbstractThe Raman spectra of 1,4‐dibromobut‐2‐yne (BrBr) as a liquid at various temperatures and as an amorphous and crystalline solid at low temperatures were recorded in the 3200‐10 cm−1 region. IR spectra of the liquid at room temperature and of the amorphous and crystalline solids at low temperatures (4000‐50 cm−1) were obtained. Additional IR spectra of the vapour were recorded (4000‐500 cm−1). The spectra of the liquid phase showed characteristic, broad bands below 500 cm−1. No temperature dependence was detected in these, and the spectra of the amorphous solid at 90 K are almost identical with the room temperature spectra of the liquid. A shoulder on the Rayleigh line was observed at ca. 20 cm−1 in the Raman spectrum of the amorphous BrBr at 90 K which tentatively, has been interpreted as the torsional mode. In the crystal an anti conformer was present, while the spectra of the vapour and the liquid were interpreted in terms of large torsional freedom. The Raman and IR spectra of the very unstable 1,4‐diiodobut‐2‐yne (II) as a crystalline solid were recorded in the 4000‐20 cm−1 range at low temperatures. Spectra of carbon disulphide solutions at temperatures 250–260 K were obtained and additional IR spectra of II in Nujol mulls and in KBr pellets were also recorded. In the region below 500 cm−1, Where other 1,4‐dihalobut‐2‐ynes have characteristic, broad bands, a high irregular background was observed in the Raman spectrum of II in solution. The spectra agree with an anti conformer present in the crystal and nearly free internal rotation in the liquid. The vibrational assignments are supported by force constant calculations and by a correlation diagram for the vibrations of the six skeletal bending modes in 1,4‐dichlorobut‐2‐yne, BrBr and II.
SERS study of the conformational transition of the ordering of lipid molecules deposited on a silver electrode
Authors: Guo F. C. , Chou Y. C. , Huang W. N. , Wu Wen‐Guey 
Published: May 2005

AbstractDipalmitoylphosphatidylcholine lipid molecules adsorbed on a silver electrode were found to exhibit a conformational phase transition when investigated by means of surface‐enhanced Raman scattering. The observed order‐to‐disorder transition of the hydrocarbon chain is voltage dependent and exhibits hysteresis phenomena. It is suggested that the adsorption of lipid molecules occurs at the phosphocholine moiety and the kinetic process for the transition involves a voltage‐induced conformational change of the head group.
Vibrational spectra of indole and assignments on the basis of ab initio force fields
Authors: Majoube M. , Vergoten G. 
Published: May 2005

AbstractNew high‐resolution Fourier transform spectra for indole vapour and its N‐deuterated analogue and Fourier transform Raman spectra for solid indole are reported. Observed frequencies for normal modes are compared with those calculated from normal coordinate analyses carried out on the basis of ab initio force fields. The latter were calculated using the 3–21G basis set and either the theoretical optimized geometry or that given by microwave spectroscopy. The force field obtained with the optimized geometry was shown to provide and excellent approach for calculating not only frequencies but also IR and Raman intensities. Except for the NH and CH stretching modes, only one scale factor for all the in‐plane modes and another for all the out‐of‐plane modes are needed in order to bring closer the calculated and observed frequencies for indole and for eleven deuterated analogues. Assignments for each normal mode were obtained from potential energy distributions among internal coordinates. Those for normal modes corresponding, in particular, to bands observed also for the tryptophar residue are discussed in detail.
High‐pressure Raman study of methyl iodide (CH3I and CD3I) up to 12 GPa
Authors: Wu Y. H. , Sasaki S. , Shimizu H. 
Published: May 2005

AbstractHigh‐pressure Raman spectra of liquid and crystalline CH3I and CD3I were measured up to 12 GPa at 300 K in a gasketed diamond‐anvil cell. The liquid‐solid phase transition pressures were determined as 0.9 GPa for CH3I and 0.8 GPa for CD3I. For both CH3I and CD3I, two translational and two librational modes were observed in the pressure‐induced solid phase. The frequencies of the librational modes increased rapidly with increasing pressure. The frequency of the intense ν3 mode also increased rapidly with pressure. Splitting of fundamental modes was found in the solid phase, and this behaviour is discussed in terms of crystal field effects.
Raman and infrared spectra of solid bromotrifluoromethane
Authors: Zakhary N. M. , Schlueter S. A. , Anderson A. 
Published: May 2005

AbstractRaman and infrared spectra of solid bromotrifluoromethane were recorded in both the internal and lattice mode regions at temperatures between 12 K and the melting point. No evidence of a solid‐state phase transition was found. Lattice peaks were assigned on the basis of geometrical and intensity arguments, and splittings of internal modes were interpreted in terms of isotopic or crystal field effects. A non‐centrosymmetric unit cell containing four molecules was shown to be compatible with the observed spectra.
Interference effects in the intensity of coherent anti‐stokes Raman scattering in thin samples
Authors: Kukk Peeter 
Published: May 2005

AbstractThe interference effects on the intensity of coherent anti‐Stokes Raman scattering (CARS) in thin samples of high optical quality were shown to be determined by the interference in the sample of the four lightwaves active in this non‐linear four‐wave mixing process. In the calculation of the contrast factor in the linear and non‐linear interference spectra, the optical inhomogeneities of real samples were also taken into consideration. Theoretical equations were derived which describe well the experimentally measured CARS interference spectra of thin (0.14 mm) glass. However, in the case of thin anthracene monocrystalline flakes with optical inhomogeneities, a discrepancy between the theoretical calculations and experimental data was found.
Raman and infrared spectra of solid dibromodifluoromethane
Authors: Eix S. L. , Schlueter S. A. , Anderson A. 
Published: May 2005

AbstractRaman and infrared spectra of soiid dibromodifluoromethane are reported for both the lattice and internal mode regions at temperatures between 12 K and the melting point. No evidence was found for a solid‐state phase transition. Plausible assignments of all observed spectroscopic features are suggested. The spectra are compatible with a non‐centrosymmetric unit cell containing four molecules.
Vibrational studies of the disulfide group in proteins. VII. Normal mode analysis of the Raman spectra of erabutoxin, γ‐II crystallin and immunoglobulin
Authors: Qian Weili , Krimm Samuel 
Published: May 2005

AbstractNormal mode calculations have been made on the known structures of disulfide bridges in erabutoxin b, a form of γ‐II crystallin, and fragments (Fab, variable‐domain of Bence‐Jones proteins) of immunoglobulins. Previously obtained Raman spectra of these molecules are analyzed in terms of general correlations derived from normal mode calculations and also the results of calculations on these particular structures. This results in more specific conclusions about these disulfide bridge structures and their changes than was possible on the basis of previous empirical correlations.
Influence of the non‐diagonal part of the potential energy matrix in the SbC13 molecule on the results of calculating the force constants of intermolecular interaction
Authors: Kondyurin A. V. , Byelousova N. K. , Byelousova S. L. , Kozulin A. T. 
Published: May 2005

AbstractRaman spectra of antimony trichloride in various phases and in crystals of complexes with naphthalene and p‐xylene were measured. Normal coordinate analyses with different approximations for the potential energy matrix of SbCl3 were performed. The frequencies of lattice modes and half‐periods of rotational librations of the SbCl3 molecule were determined. The non‐diagonal elements of the potential energy matrix of AB3 molecules (in particular SbCl3) were shown to be insensitive to the intermolecular interaction. A normal coordinate analysis for SbCl3 intramolecular vibrations can be made using as an approximation only the diagonal part of the potential energy matrix for calculating the parameters of intermolecular interaction, which significantly simplifies the calculation and gives sufficient accuracy.