bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman studies on the structures and properties of the compounds formed in the CdCl2CsCl binary system
Authors: Brooker Murray H. , Wang Jianfang 
Published: May 2005

AbstractRaman spectra were obtained for the solid phases formed from binary mixtures of the CdCl2 and CsCl salts. Five compounds were identified, three congruent (Cs3CdCl5, Cs2CdCl4 and CsCdCl3) and two incongrnent (Cs3Cd2Cl7 and CsCd5Cl11). Unlike the potassium and rubidium systems, there was no evidence to suggest the formation of a solid with a discrete octahedrally coordinated species as has been found in K4CdCl6 and Rb4CdCl6. Cs3CdCl5 is isostructural with Cs3CoCl5, space group I 4/mcm (D), and contains the discrete CdCl; it forms from the melt and is thermodynamically stable only above 390°C. Below 390°C Cs3CdCl5 normally decomposes into a mixture of Cs2CdCl4 and CsCl, but the sample may be quenched to room temperature to give metastable Cs3CdCl5, which converts to Cs2CdCl4 and CsCl when warmed to 200°C. Cs2CdCl4 has the K2NiF4 structure in the lowtemperature phase, space group I4/mmm (D), but this salt undergoes a phase transition at a β‐K2SO4‐type high temperature phase, space group P nma (D) with discrete CdCl. The transition occurs over the temperature range 370–460°C. A dynamic equilibrium between the two solid phases within the temperature range has been inferred. Cs3Cd2Cl7 has been reported to be isostructural with Rb3Mn2Cl7 at room temperature but it decomposes into CsCdCI3 and Cs2CdCl4 at temperatures above 450°C. The structure of CsCd5Cl11 is not yet known but the Raman spectrum suggested that the Cd atoms have octahedral coordination within a network structure. CsCdCl3 is hexagonal, space group P63/mmc, and the Raman studies indicated that there was no structural phase transition from 25°C to the melting point.
Stimulated Raman gain spectroscopy seeded by amplified spontaneous emission
Authors: Wong K. H. , Ho W. L. , Tsui W. L. 
Published: May 2005

AbstractAn amplified spontaneous emission (ASE) seeded broadband pulsed stimulated Raman gain spectroscopy (SRGS) technique is described. The ASE of a dye laser and the dye laser itself are used as a broadband probe and the pump beam, respectively. The overall optical arrangement is simple and easy to implement. The technique has been demonstrated to have excellent background fluorescence rejection capability. Raman spectra of low‐concentration NO3 − and SO dissolved in a strongly fluorescent solution have been obtained.
Raman studies of crystalline and amorphous poly(p‐phenylene sulfide) films
Authors: Pan Z. , Savard T. , Wicksted J. P. 
Published: May 2005

AbstractRaman spectra of biaxial crystalline and amorphous poly(p‐phenylene sulfide) (PPS) films were recorded using the micro‐Raman technique. The Raman spectra of its corresponding trimer and tetramer from KBr pellets and the infrared spectrum from the PPS film were also recorded in order to elucidate the normal vibrational modes in PPS. The difference in the Raman spectra between biaxial and amorphous films is presented. New modes are observed at 840 and 919 cm−1 in the polymer films which had been missing in a previous study and the phenylene—sulfur stretching vibrations in the PPS chain, which are used to characterize the peak at 1076 cm−1, are discussed. It was also found that the broad fluorescence background, when excited at 514.5 nm, reaches its peak value at about 598 nm for the biaxial film and at about 616 nm for the amorphous film.
Raman and infrared spectra, conformational stability, barriers to internal rotation, vibrational assignment, and ab initio calculations for 3‐iodopropene
Authors: Durig J. R. , Tang Qun , Little T. S. 
Published: May 2005

AbstractThe Raman spectra (3200—10 cm−1) of gaseous, liquid and solid and infrared spectra (3200—40 cm−1) of gaseous and solid 3‐iodopropene, H2CCHCH2I, were recorded. The fundamental asymmetric torsional transition of the most stable gauche conformer was observed in the Raman and far‐infrared spectra of the gas at 95 cm −1. In the Raman spectrum of the liquid a second CI stretch and two skeletal bending modes were identified for the less stable cis conformer. From a study of the Raman spectrum of the liquid at various temperatures, a value of 648±81 cm−1 (1.85±0.23 kcal mol−1)was determined for the enthalpy difference between the higher energy cis and preferred gauche conformers. These data, along with the dihedral angle for the gauche conformer obtained from an electron diffraction study, combined with results obtained from ab initio calculations, allow for an estimate of the potential function governing internal rotation about the CC bond. The values for the torsional potential coefficients are V1 = −208 ± 10, V2 = −532 ± 10, and V3 = 534 ± 8 cm−1. This potential is consistent with a dihedral angle (∠ CCCI) of 113.0° for the gauche conformer cis to gauche, gauche to gauche and gauche to cis barriers of 160, 904 and 738 cm−1, respectively, and an enthalpy difference between the conformers of 580 ± 30 cm−1 (1.66 ± 0.09 kcal mol−1). The asymmetric torsional potential surface, complete equilibrium geometries and vibrational frequencies were calculated using restricted Hartree‐Fock calculations with the STO‐3G*, 3‐21G*/medium, a medium‐sized combination basis set suitable for a DZ‐type contraction of the valence shell orbitals, and the LANL1DZ basis sets. All of these results are discussed and compared with the corresponding quantities obtained for some similar molecules.
Raman and infrared spectra, conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment for bromodifluoroacetyl chloride
Authors: Mohamed Tarek A. , Stidham Howard D. , Guirgis G. A. , Phan H. V. , Durig J. R. 
Published: May 2005

AbstractThe Raman (1800–10 cm−1) and infrared (2000–30 cm−1) spectra of bromodifluoroacetyl chloride, CBrF2CClO, are reported for the gas and polycrystalline solid. Additionally, the Raman spectrum of the liquid along with qualitative depolarization ratios have also been obtained. These data have been interpreted on the basis of an equilibrium between the gauche and the trans conformers (bromine atom trans to the chlorine atom) in the gas and liquid phases. From a study of the Raman spectrum of the liquid at various temperatures, a value of 851 ± 56 cm−1 (2.43 ± 0.07 kcal mol−1) was obtained for ΔH with the gauche conformer the more stable form. A similar study of the gas gave a value of 725 ± 150 cm−1 (2.07 ± 0.43 kcal mol−1), again with the gauche rotamer the more stable conformer. Hence the gauche conformer is the predominate rotamer in the gas and liquid and the only conformer present in the annealed solid. Aided by ab initio and scaled computations of the vibrational spectrum with the STO‐3G* basis set and, for the trans conformer at the 4–31G*/MIDI‐4* level of the theory, complete assignments of observed bands to fundamental vibrations of the gauche conformer are made, whereas partial assignment is reported for the trans conformer. The fundamental torsional mode for the gauche conformer was observed at 46 cm−1 but excited‐state transitions were not observed so the potential function governing the conformational interchange could not be determined. Optimized geometries, dipole moments, unscaled and scaled vibrational frequencies and harmonic force fields are reported for both conformers. With the STO‐3G*, basis set, the gauche conformer is calculated to be more stable than the trans conformer by 17 cm−1 (48 cal mole−1). These results are compared with the corresponding quantities for some similar molecules.
Pressure‐induced phase transitions in LiRbSO4: a Raman spectroscopic study
Authors: Shashikala M. N. , Chandrabhas N. , Jayaram K. , Jayaraman A. , Sood A. K. 
Published: May 2005

AbstractRoom‐temperature Raman spectra of LiRbSO4 were studied as a function of pressure up to 170 kbar for two different orientations of the crystal. Four pressure‐induced phase transitions at about 2, 17, 32 and 57 kbar were observed. The transitions at 17 and 57 kbar have slow kinetics, taking about 4 h for their completion. These phase transitions are associated with the orientations of the SO4 ions in the unit cell.
Structural phase transitions in RbLiSO4
Authors: Lemos V. , Camargo F. , Hernandes A. C. , Freire P. T. C. 
Published: May 2005

AbstractUnpolarized Raman spectra of RbLiSO4 were obtained for pressures in the range 1 atm–9.5 GPa. Several modifications observed in the spectra were interpreted in terms of two‐phase transitions. The critical pressures for these transitions were determined at 2.5 and 5.5 GPa on increasing the pressure. The first transition is irreversible and can also occur for pressures >2.5 GPa, although through a process varying slowly. The higher pressure transition is reversible but with a marked hysteresis.
Conformational analysis and vibrational spectra of isopropyl formate and some deuterated isotopomers
Authors: Rosas R. L. , Liefooghe H. H. , Laane J. , van der Veken B. J. 
Published: May 2005

AbstractRaman spectra of vapor, liquid and low‐temperature crystalline phases and infrared spectra of vapor and low‐temperature amorphous and crystalline phases of isopropylformate [HCOOCH(CH3)2] and of four of its isotopomers, DCOOCH(CH3)2, DCOOCH(CD3)2, HCOOCD(CD3)2 and DCOOCD(CD3)2, are reported. The spectra indicate on dominant conformer in all the phases studied. In the vapor and liquid phases, however, indications are found for the presence of a small amount of a second conformer which is believed to have the s‐trsn ester conformation. Vapor‐phase asymmetric‐top infrared contour simulation of the carbonyl stretching vibration shows that for the principal conformer the ester function has s‐cis conformation whereas the isopropyl group shows a quasi‐gauche orientation.
Investigation of adsorption and decomposition of 4‐(methylthio)benzonitrile on a silver surface by Raman spectroscopy
Authors: Yi Sung Soo , Kim Kwan , Kim Myung Soo 
Published: May 2005

AbstractSurface‐enhanced Raman scattering of 4‐(methylthio)benzonitrile (4MTB) adsorbed on a silver surface was investigated. The molecule was found to adsorb on the surface via its sulphur atom and nitrile group. By reference to the spectral correlation scheme in coordination chemistry, surface binding of the latter group was concluded to occur through both s̀ donation and π back‐donation. The benzene ring of 4MTB was deduced to be tilted with respect to the surface plane. In the adsorbed state, 4MTB was also observed to undergo surface‐induced photoreaction. The reaction product, presumably p‐cyanophenyl mercaptide, appeared to assume a much flatter orientation than its precursor due to stronger interaction of the mercaptide with the surface than that of sulphide.
Compositional dependence of spectral features in the Raman spectra of erythrocyte membranes
Authors: Goheen S. C. , Lis L. J. , Kucuk O. , Westerman M. P. , Kauffman J. W. 
Published: May 2005

AbstractThe Raman spectra of erythrocyte membranes in water and D2O were analyzed to determine the percentage of protein and lipid contributions to the amide I spectral feature. The approach of Lippertet al. [J. Am. Chem. Soc.98, 7075 (1976)] was modified to use circular dichroism data for protein conformations of erythrocyte membranes to determine the relative lipid and protein contributions to the 1660 cm−1spectral feature. It was determined that 69 ± 15% of the measured peak intensity was due to the protein contribution. The implication of this data to the quantity of α‐helix conformation in membrane protein of erythrocytes, and alternative approaches to determine protein conformation from Raman spectra are discussed.
Non‐adiabatic effects on resonance‐enhanced Raman scattering in H2
Authors: Banerjee Sima , Bhattacharyya S. S. , Saha Samir 
Published: May 2005

AbstractResonance‐enhanced Raman scattering (RERS) from the ground X1Σg+(νg = 0, Jg) state of H2 via the excited intermediate C1Πu(ν = 0/1/2/3, Ji) state coupled non‐adiabatically with the B1Σu+(νiB = 8/10/12/14, Ji) state was studied theoretically, applying second‐order perturbation theory. The excitation and Raman spectra for the pure rotational, fundamental and higher overtones are presented. Effects of non‐adiabatic coupling on the excitation profiles, scattered intensities and depolarization ratios were investigated. The intensities of excitation spectra and Raman lines for O‐, Q‐ and S‐branches were calculated using thermal Boltzmann factors for vibrational–rotational distribution at room temperature (300 K). The RERS cross‐sections with adiabatic and non‐adiabatic corrections are reported together with Born–Oppenheimer (BO) results where available, for comparison. The calculated RERS cross‐sections including non‐adiabatic effects were found to vary significantly from adiabatic or BO results.
Crossing of anisotropic and isotropic Raman components in the intermolecular resonance coupling of vibrations
Authors: Sokołowska Anna , Kęcki Zbigniew 
Published: May 2005

AbstractChanges in the frequencies of the anisotropic and isotropic components of the OH bands in the Raman spectrum of aqueous, methanolic and ethanolic solutions of LiCl were investigated. With increased concentrations of LiCl a crossing of the components i.e. exchange of their positions, was observed, and the non‐coincidence values Δν = νaniso – νiso of the OH bands changed from positive to decidely negative. The results obtained suggest that some revision of existing theories of non‐coincidence is desirable.
Resonance Raman study of solvent effects on a series of triarylmethane dyes
Authors: Lueck Horst B. , Daniel Douglas C. , McHale Jeanne L. 
Published: May 2005

AbstractResonance Raman spectroscopy was used to address questions concerning the influence of the solvent on the structure and aggregation state of a series of triarylmethane dyes. These molecules are of interest owing to the dramatic solvent effects exhibited in their optical absorption spectra, which have recently been interpreted in terms of intermolecular interactions which perturb the D3 symmetry of the cationic dyes. Raman spectra of parafuchsin, malachite green, crystal violet and ethyl violet were compared in various solvents, in order to explore changes in the vibrational modes brought about by aggregation (in water), ion‐pair formation (in non‐polar solvents) and ion–dipole interactions (in polar solution). In triply amino‐substituted dyes, the data point to the possibility that a resonance structure exists having a positive charge on one of the three nitrogens. It is discussed how the resulting reduction in the expected D3 symmetry of the cation affects the resonance Raman spectrum.
Pre‐resonance Raman effect on the OD stretching Raman spectra of methanolic LiX solutions (X = Cl, Br and I)
Authors: Kanno Hitoshi , Yamauchi Shigeru 
Published: May 2005

AbstractIntensities of the OD stretching modes in the Raman spectra of LiX solutions (X = Cl, Br and I) in CH3OD were measured. It is shown that the intensities increase significantly with increasing halide concentration owing to a pre‐resonance Raman effect arising from charge‐transfer states of hydrogen bonds between halide ions and their solvated methanol molecules. The small dissociation of dissobed Lil molecules is the reason why no enhancement of the intensity is observed in the Raman OD stretching spectrum for a glassy methanolic LiI solution.
Near‐infrared fourier transform Raman spectroscopic characterization of transition metal carbonyl complexes embedded in thin films of polystyrene, poly(methyl methacrylate) and polystyrene–polyacrylonitrile
Authors: Markwell Ross D. , Butler Ian S. , Gao Jian Ping , Shaver Alan 
Published: May 2005

AbstractThin films of polystyrene (PS), polystyrene–polyacrylonitrile (PS–AN) copolymer and poly(methyl methacrylate) (PMMA) containing embedded transition metal carbonyls were characterized by near‐IR Fourier transform (FT) Raman spectroscopy. Several of the films were also examined by FT‐Raman microspectroscopy and the distribution of the metal carbonyls throughout the films was determined by a 2D mapping procedure similar to that described earlier for 2D IR microspectroscopy. The results indicate that the 2D FT‐Raman approach is particularly useful for highly doped films when the absorbances of the ν(CO) modes in the IR spectra of the metal carbonyls are too large to measure accurately. The films are more sensitive to thermal decomposition induced by near‐IR laser irradiation than are the solid metal carbonyls and the PS films are more susceptible than are the PMMA films.
Near‐infrared fourier transform Raman microspectroscopy at high external pressures
Authors: Barnett Steven M. , Markwell Ross D. , Brienne Stéphane H. R. , Butler Ian S. , Gilson Denis F. R. , Kawai Nancy T. , Vlček Antonín 
Published: May 2005

AbstractNear‐IR Fourier transform (FT) Raman spectroscopic measurements were performed at high pressures for the first time by mounting a diamond‐anvil cell on the optical stage of an FT‐Raman microprobe equipped with a long‐range 4 × objective and by using a near‐IR (Nd: YAG, 1064.1 nm) laser to excite the sample. The utility of this new pressure‐tuning Raman microspectroscopic method was demonstrated by its successful application to a typical organometallic complex, Cr(CO)4(bipy)(bipy = 2.2′‐bipyridyl), which decomposes under conventional visible Raman spectroscopic conditions.
Orientational order in polyethylene foils: A polarized Raman spectroscopic study
Authors: Kip Bert J. , van Gurp Marnix , van Heel Sef P. C. , Meier Robert J. 
Published: May 2005

AbstractPolarized Raman spectroscopy was used to determine the order parameters of the orientational distribution function for a series of stretched polyethylene foils with a relatively low degree of molecular orientational order. By combining measurements of the foil under stduy and of an isotropic polyethylene foil, simple backscattering experiments are sufficient to determine the orientation order parameters of the foil with molecular orientation. Practical considerations for obtaining polarized Raman spectra are discussed. The results are in good agreement with the order parameters obtained by IR dichroism and wide‐angle x‐ray diffraction. Differences between the various methods are discussed. The Raman method proves to be a relatively rapid method for obtaining information concerning the molecular orientation in polyethylene films.
Elimination of signal fluctuations in CARS of weak resonances in liquids
Authors: Apanasevich P. A. , Kozich V. P. , Vodchitz A. I. 
Published: May 2005

AbstractA technique for decreasing the influence on spectra of CARS signal fluctuations was tested experimentally. The proposed technique is based on the normalization of the detected CARS signal to the reference signal which is generated simultaneously in the same volume of interaction through four‐wave mixing of two exciting beams in a Kerr‐shutter configuration.
Use of colloidal SERS for the trace detection of organic species: a survey based on pyridine as the probe molecule
Authors: Cook Jeanette C. , Cuypers C. M. P. , Kip Bert J. , Meier Robert J. , Koglin E. 
Published: May 2005

AbstractIn view of the reported extreme sensitivity of surface enhanced Raman spectroscopy, the potential of colloidal silver and gold sols for the purpose of semi‐quantitative trace analysis of organic molecules was investigated. High irreproducibility in Raman intensities is reported regarding most of the variables that come into play when preparing the sols, e.g. stirring rate, addition time of chloride ions and ageing. Experimental enhancement factors differ by orders of magnitude even for sols prepared from the same recipe. The value of colloidal SERS for analytical purposes, in particular when employing silver sols, therefore seems to be limited to qualitative analysis.
Low‐wavenumber vibrational Raman optical activity of carbohydrates
Authors: Bell Alasdair F. , Hecht Lutz , Barron Laurence D. 
Published: May 2005

AbstractA high optical density holographic notch filter in combination with a single‐grating spectrograph was used to increase the spectral range for backscattered Raman optical activity (ROA) measurements of biological molecules in aqueous solution towards lower wavenumber. ROA spectra of D‐galactose, D‐maltose and laminarin starting at ca. 350 cm−1 are presented as first examples. An ROA couplet observed at 427 ± 10 cm−1 in the spectra of D‐maltose, D‐cellobiose and laminarin appears to reflect the configuration of glycosidic links in di‐ and poly‐saccharides.
Resonance Raman scattering of multimode systems: Fourier amplitude approach
Authors: Hizhnyakov V. , Tehver I. 
Published: May 2005

AbstractThe time‐dependent description of resonance Raman scattering of multimode systems is presented and discussed. The basic quantities of the theory are the Fourier transforms of the Raman amplitudes. For a number of vibronic models they are related to the optical absorption. These relationships enable one to transform the absorption spectrum to the Raman excitation profiles. In the transform method, model parameters are needed only for the Raman mode; the multimode information is automatically included via the measured optical absorption. The method holds for an arbitrary temperature. Transform relationships are derived for the basic model of linear vibronic coupling and for more complicated models including linear non‐Condon interaction, frequency shifts and mode mixing with electronic excitation, the Jahn–Teller effect and inhomogeneous broadening.
Antiresonance in hyper‐Raman excitation spectra
Authors: Hassing S. , Svendsen E. Nørby 
Published: May 2005

AbstractA scattering model of interference between the Franck–Condon and Herzberg–Teller terms was studied in the preresonance regions of hyper‐Raman spectroscopy. It is shown how profound antiresonance effects are connected with molecular properties such as potential curve displacement and vibronic coupling parameters.
Raman and infrared spectra, conformational stability, barriers to internal rotation, vibrational assignment and ab initio calculations of trans‐1‐bromobut‐2‐ene
Authors: Durig J. R. , Costner T. G. , Goodson Burt 
Published: May 2005

AbstractRaman (3200–10 cm−1) and infrared (3200–20 cm−1) spectra were recorded for the fluid and solid phases of trans‐1‐bromobut‐2‐ene (crotyl bromide), trans‐CH3CHCHCH2BR, and a complete vibrational assignment is proposed. The fundamental asymmetric torsion for the more stable gauche conformer was observed in the far‐infrared spectrum of the gas as a hybrid band centered at 75.0 cm−1. The enthalpy difference between the gauche and syn conformers is estimated to be 434 ± 111 cm−1 (1.24 ± 0.32 kcal mol−1) in the gas phase from the relative intensities of the Raman lines utilizing the differences in the Raman activities from the ab initio calculations with the RHF/STO‐3G* basis set. The enthalpy difference was determined experimentally for the liquid from the relative intensities of the C–Br stretches as a function of temperature. The determined value is 370 ± 77 cm−1 (1.06 ± 0.22 kcal mol−1) with the gauche conformer the more stable form. A reasonable range of values was obtained for the coefficients of the potential function governing internal rotation about the CC bond. The three‐fold barrier governing internal rotation of the CH3 group was determined from the far‐infrared spectrum of the gas. All of these data are compared to the corresponding quantities obtained from ab initio Hartree–Fock gradient calculations employing the RHF/STO‐3G* and RHF/LANL1DZ basis sets. Additionally, complete equilibrium geometries were determined for both rotamers. The results are discussed and compared with the corresponding quantities for some similar molecules.