bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Raman study of the misfit layer compounds, (SnS)1.17NbS2 and (PbS)1.18 TiS2
Authors: Sourisseau C. , Cavagnat R. , Tirado J. L. 
Published: May 2005

AbstractThe Raman and resonance Raman spectra (850–20 cm−1) of powdered samples of the misfit layer compounds (SnS)1.17NbS2 and (PbS)1.18TiS2 at 300 K have been investigated. In partial agreement with structural data, vibrational assignments are proposed for most of the internal modes of the ‘MS’ and ‘TS2’ sublattices and the band wavenumbers are compared to those in the 2H‐NbS2 and IT‐TiS2 prototypes, in order to understand the interaction in which ‘MS’ acts as the donor part of the structure. Owing to their incommensurate modulated structures along the {ξ00} direction, characteristic Raman bands at 197 cm−1 (‘SnNbS3’) or 203 cm−1 (‘PbTiS3’), assigned to mostly TA or LA type modes, become Raman active due to a zone folding mechanism. New information about the lattice dynamics in the ‘TS2’ sublayers is thus obtained.
Resonance Raman spectra of Ru(bpz) in aqueous sulfuric acid solutions
Authors: Danzer Gerald D. , Kincaid James R. 
Published: May 2005

AbstractThe resonance Raman spectra of tris(2,2′‐bipyrazine)ruthenium(II) complex, Ru(bpz), were obtained in solutions of H2SO4‐H2O and 2H2SO4‐2H2O at acid concentrations between 0 and 98 wt.%. The spectral results are consistent with sequential protonation (or deuteration) of the six peripheral nitrogen atoms, the first three protons being added to separate bipyrazine ligands to form Ru(bpzH+). These findings are in agreement with the conclusions of previous studies based on electronic absorption and emission spectra.
Raman and infrared spectra of solid tribromofluoromethane
Authors: Zakhary N. M. , Schlueter S. A. , Anderson A. 
Published: May 2005

AbstractVibrational spectra of solid tribromofluoromethane at temperatures between 12 K and the melting point were obtained using Raman and infrared techniques, with special emphasis on the lattice modes. No evidence for a solid‐state phase transition was found. Lattice peaks are tentatively assigned on the basis of geometrical and intensity arguments. It is shown that the spectra are compatible with a non‐centrosymmetric unit cell containing four molecules.
CARS difference spectroscopy. II—Determination of small frequency shifts and band width changes in binary mixtures
Authors: Weippert A. , Kiefer W. 
Published: May 2005

AbstractThe experimental verification of CARS difference spectroscopy (CARS‐DS) is presented and its application to binary mixtures is shown. The experimental set‐up allows the simultaneous measurement of CARS spectra of two different samples under identical conditions. It is shown how the method can be used for the accurate determination of small frequency shifts and band width changes in liquid mixtures. The experimental spectra obtained were analysed by their numerical simulation using a least‐squares fitting routine. As examples, experimental results for chloroform–deuterochloroform isotopic mixtures and binary mixtures of benzene and toluene of different concentrations are presented. In both cases frequency shifts and changes in the band width were observed which exhibit an almost linear dependence on the mole fraction of the probe species.
Resonance Raman investigation of the state of polyiodides in the organic conductors (PEDT‐DTDSF)2I3 and (PDM‐TTF)3I3
Authors: Zambounis J. S. , Kamitsos E. I. , Papavassiliou G. C. 
Published: May 2005

AbstractThe resonance Raman spectra of (PEDT‐DTDSF)2I3 and (PDM‐TTF)3I3 organic conductors were measured and analysed to investigate the state of the polyiodide counterions. It was found that both compounds are characterized by the coexistence of I3− and I5− species. The relative concentration of these polyiodides has been shown to be temperature dependent only for the first compound. This was attributed to a thermally induced disordering of the triiodide chains, which leads to a dynamic formation of pentaiodides with increasing temperature.
Multi‐channel micro‐Raman spectroscopy with near‐infrared excitation. II
Authors: Barbillat J. , Da Silva E. , Hallaert J. L. 
Published: May 2005

AbstractThe performances of a multiplexed near‐infrared (NIR) germanium detector and of a InGaAs photodiode‐array detector are reported. Their use with an Nd: YAG laser at 1.064 μm to obtain high‐quality fluorescence‐free Raman spectra of micro‐samples is illustrated. A comparison with Fourier transform Raman spectra of much larger samples demonstrates that NIR multi‐channel Raman spectroscopy is competitive for fluorescence‐free measurement of Raman spectra.
Spectroscopic behaviour of the two CO stretching vibrations in free and complexed theophylline
Authors: Tarulli Susana , Baran Enrique J. 
Published: May 2005

AbstractThe behaviour of the stretching vibration of the two CO groups in free theophylline and in some of its metallic complexes of stoichiometry [MII(tp)2(H2O)4] were investigated by means of infrared and Raman spectroscopy. It is demonstrated that after complexation an inversion of the relative band positions of these two stretching modes takes place. This behaviour could be clearly explained on the basis of the structural characteristics of the investigated complexes.
Raman and surface‐enhanced Raman spectroscopic studies of sulphanilic acid azochromotrope (SPADNS)
Authors: Siu G. G. , Chen Z. L. 
Published: May 2005

AbstractThe trisodium salt of 2‐(4‐sulphophenylazo)‐1,8‐dihydroxynaphthalene‐3,6‐disulphonic acid (SPADNS) was studied by Raman and surface‐enhanced Raman spectroscopy (SERS) techniques. The Raman spectra of SPADNS powder and aqueous solution were investigated and an assignment of the Raman bands was made taking into account its infrared absorpiton spectrum. SPADNS tatomers, o‐hydroxyazo and o‐quinone hydrazone, are also discussed. Although the assignment is still preliminary owing to the complex structure of the SPADNS molecule, it provides useful information for SERS investigations of SPADNS in aqueous silver sol and on silve film. The results of SERS are compared with those of visible absorption spectra and x‐ray photoelectron spectra (XPS) and the adsorption configuration of the SPADNS molecule on a silver surface is considered.
Laser power dependence of Raman scattering on YBa2Cu3O7−x thin films
Authors: Liang N. T. , Tse W. S. , Chang M. C. , Chen H. T. , Chen T. T. 
Published: May 2005

AbstractGood‐quality high‐Tc YBa2Cu3O7−x thin films deposited by the laser ablation method were investigated by Raman spectrosocpy. The vibrational spectra of thin films of YBa2Cu3O7−x at various laser intensities and with different polarizations were measured. The Raman modes change on increasing the laser power and in general such changes are reversible. However, as the laser intensity is increased above a certain value, dramatic changes occur in the Raman peaks, as a result of damage to the sample.
Behaviour of the 1025 cm−1 band of SERS spectra due to pyridine on a silver electrode in aqueous halide media
Authors: Saito Hiroshi 
Published: May 2005

AbstractThe 1025 cm−1 band which occurs in the SERS of pyridine and halide anion was investigated in detail on a silver electrode in neutral and acidic solution. The 1025 cm−1 band was observed to increase in intensity when the silver electrode was treated with the ORC procedure in the presence of pyridine and halide and the concentration of pyridine was then diluted in neutral solution. On the other hand a band began to appear strongly at 1025 cm−1 when the solution was acidified with HCl after the ORC. It was confirmed that the 1025 cm−1 band appearing on dilution in neutral solution has by the same origin as the 1025 cm−1 band which appeared on acidification. The behaviour of the band can be understood if it is assumed that the species giving rise to the 1025 cm−1 band is a silver–pyridine–halide complex generated by the electrode reaction during the ORC.
Raman and infrared spectra, conformational stability, barriers to internal rotation and ab initio calculations of acetyl isocyanate
Authors: Durig J. R. , Guirgis G. A. , Krutules K. A. , Sullivan J. F. 
Published: May 2005

AbstractThe Raman (3100–10 cm−1) and infrared (3100–30 cm−1) spectra of acetyl isocyanate, CH3C(O)NCO, and the d3‐isotopomer were recorded for the gases and solids. Additionally, the Raman spectra of the liquids were recorded and qualitative depolarization values were obtained. The observed bands are assigned on the basis of the more stable cis (syn) conformer (isocyanate group cis to the carbonyl bond) and less stable trans (anti) conformer in the vapor state. ΔH of the gas is estimated to be 433 cm−1 [1.24 kcal mol−1 (1 kcal = 4.184 kJ)] from the relative intensity of the conformer pair at 800 and 763 cm−1. From the temperature dependence of the Raman spectrum of the liquid, two conformer pairs were used to determine experimentally a ΔH value of 370 ± 60 cm−1 (1.06 ± 0.17 kcal mol−1) but now with the trans conformer the more stable form. In the annealed crystalline solid, only the trans conformer remains. The fundamental asymmetric torsion of the cis conformer was observed at 79 cm−1 with two excited states falling to lower frequency. Utilizing these data and ΔH for the gas the potential function governing the conformer interchange was estimated. A complete vibrational assignment is proposed for both conformers based on infrared band contours, Raman depolarization data, group frequencies and normal coordinate calculations. The experimental confirmational stability, barriers to internal rotation and fundamental vibrational frequencies are compared with those obtained from ab initio Hartree–Fock gradient calculations employing the RHF/6–31G* basis set and to the corresponding quantities obtained for some similar molecules.
Vibrational spectra and conformation of 2,3‐diiodobuta‐1,3‐diene
Authors: Karlsson A. , Klaeboe P. , Nielsen C. J. 
Published: May 2005

AbstractRaman and infrared spectra of the very unstable compound 2,3‐diiodobuta‐1,3‐diene were recorded in the crystalline state at low temperatures in the spectral ranges 3300–10 and 4000–200 cm−1, respectively. Owing to a rapid polymerization rate at room temperature, only incomplete IR data were obtained of the sample in CCl4 solution. The vibrational spectra were analysed and support a planar anti conformer present in the cyrstal. The vibrational assignments are presented, supported by force constant calculations.
Vibrational spectra and conformations of 2,2‐di(fluoromethyl)‐1,3‐difluoropropane and assignments based upon ab initio force fields
Authors: Gatial A. , Sablinskas V. , Klaeboe P. , Powell D. L. , Nielsen C. J. 
Published: May 2005

AbstractThe IR spectra of 2,2‐di(fluoromethyl)‐1,3‐difluoropropane were recorded in the vapour and liquid states and as a solute in solvents of different polarity. Additional IR spectra were obtained for plastic and crystalline solids at low temperature and at high pressure, and also of the compound isolated in argon and nitrogen matrices, using the hot nozzle technique. Corresponding Raman spectra of the liquid, of solutions and of the plastic phase were recorded at different temperatures in addition to the crystalline solid. There are six possible staggered conformations with symmetries D2d, S4, C1*, C1, C2 and Cs in this molecule, and all but the last two were detected in the spectra. The two most stable conformers are S4 and D2d which have no 1,3‐parallel CF interactions. Among them S4 is ca. 0.5 and 1 kJ mol−1 lower in energy than D2d in the plastic phase and in the matrices, respectively, and S4 is present in the low‐temperature and high‐pressure crystals. A plastic phase, in which more conformers were present, was observed at temperatures below Tmelt and at high pressure. The C1* and C1 conformers both have enthalpies 5–10 kJ mol−1 higher than S4 and their bands are enhanced at increased temperatures both in the plastic crystal and in the matrices. They have dipole moments around 2–3 D, and the intensities of their bands increase in polar solvents. The enthalpy differences ΔH° were calculated from variable‐temperature measurements in the plastic crystal and in the matrices, and confirmed by Gaussian 90 with basis sets 6–31G* and 6–31G and by semiempirical and molecular mechanics calculations: MNDO, AM1 and MM2. A nearly complete assignment of the fundamentals belonging to S4 is presented. Additional bands are attributed to the D2d, C1* and C1 conformers from annealing experiments at different temperatures in the N2 matrix and in the amorphous phase. The assignments are based on the spectral observations and on the results of force constant calculations, involving scaled ab initio force constants.
Vibrational spectra in the region of OX stretches in SnCl2 · 2X2O (X = H or D) at room temperature
Authors: Kanesaka Isao , Ogawa Tadashi 
Published: May 2005

AbstractPolarized Raman spectra in the region of the OH stretches and the decoupled OD stretches in a crystal of SnCl2 · 2X2O (X = H or D) at room temperature are reported, together with infrared and Raman spectra in the polycrystalline state. Seven decoupled modes for four types of hydrogen bond were observed, which were assigned on the basis of six types of water configuration. A slight shift was found for some bands above 3350 cm−1 on going from the decoupled to the coupled state. The Raman band assigned to the in‐phase v1 mode was observed at 3060 (2275) cm−1 in the H (D) system, which was only lower by 89 (54) cm−1 than the decoupled mode. These spectra were analysed on the basis of a force field with intra‐ and intermolecular interaction constants using 72 water molecules with disorder in the hydrogen positions which satisfy a periodic boundary condition. The observed spectra were essentially explained in terms of the initial set of force constants, except for a medium band at ca. 3200 cm−1, which was accounted for using a shoulder in the decoupled spectra.
Raman spectroscopic study of the conformational equilibrium of liquid 3‐fluorostyrene
Authors: Ribeiro‐Claro P. J. A. , Teixeira‐Dias J. J. C. 
Published: May 2005

AbstractThe Raman spectra of liquid 3‐fluorostyrene show pairs of bands whose temperature‐dependent intensities clearly suggest the occurrence of a conformational equilibrium. From these bands, assigned to cis and trans conformers, a trans–cis energy difference of 0.70 ± 0.20 kJ mol−1 was obtained for the liquid phase, higher than the reported gas‐phase microwave and ab initio values. The effects of dilution with several solvents of different polarity properties are reported and the improved relative stability of the cis form in high‐polarity solvents is interpreted in terms of medium effects on intramolecular through‐space dipole–dipole interactions.
Use of the transform method in the interpretation of the Raman excitation profiles of a bichromophoric system
Authors: Ribeiro Mauro C. C. , de Oliveira Luiz F. C. , Constantino Vera R. L. , Toma Henrique E. , Santos Paulo S. 
Published: May 2005

AbstractThe use of the transform method was extended so as to permit the treatment of the resonance Raman effect with the participation of two interfering electronic transitions. The relevant equations were tested in the model system [Ru(bipy)2(violurate)]PF6, the Raman excitation profiles of which show clearly the presence of two chromophoric moieties. The present results strongly suggest that the two relevant excited states participate by means of Albrecht's A terms, whereas the vibronic coupling by the B term is not decisive. The independence of the two chromophoric moieties is reflected in distinct displacements of the respective potential minima.
Fourier transform Raman spectroscopic detector system for the analysis of polymers by gel permeation chromatography
Authors: Edwards H. G. M. , Johnson A. F. , Lewis I. R. 
Published: May 2005

AbstractAn attempt was made to use a Fourier transform (FT) Raman spectrometer as a detector with a gel permeation chromatograph which was otherwise configured in the usual way for the measurement of molar mass distribution in polymers. A low‐volume flow cell was constructed and the detector response tested both off‐line and, in a preliminary way, in‐line with the chromatograph. The particular objective was to establish whether it would be possible to measure the microstructural variation in polybutadiene with polymer molecular weight during the chromatographic process. The detector sensitivity was assessed for a range of polybutadienes with different cis‐1,4‐, trans‐1,4‐ and vinyl‐1,2‐ contents using tetrahydrofuran as solvent and eluent. Data obtained using visible Raman (488.0 nm) excitation and near‐infrared (1064 nm) excitation were compared. Although it has been established that the Raman spectrometer is one of the best instruments for the evaluation of the microstructure of polybutadiene when used in a conventional way, it lacks the necessary sensitivity to provide quantitative information on polydienes which elute from a chromatograph. However, there is no reason in principle why an FT‐Raman spectrometer should not be used as a concentration detector and for the simultaneous more detailed analysis of polymer composition or micro‐structure during the chromatographic process, provided that the scattering intensity of the solute is high relative to the eluent. The potential advantages and the observed problems of what appears to be a novel experiment with an FT‐Raman instrument are discussed.
Application of Raman spectroscopy to industrial ion‐exchange membranes. 3—poly‐4‐vinylpyridinium membranes
Authors: Bribes J.‐L. , Hasdou A. , Maillols J. 
Published: May 2005

AbstractRaman spectra of poly‐4‐vinylpyridinium anion‐exchange membranes, immersed in aqueous solutions, were recorded. Assignments of some specific vibrational bands are proposed, allowing intensity measurements of appropriate signals versus pH or time. Membranes with low intrinsic pK values were analysed and the results were in agreement with those obtained by other techniques. Deprotonation kinetic data were obtained in relation to the reduced proton leakage of these materials.
Analysis of the deformation of aramid fibres and composites using Raman spectroscopy
Authors: Andrews M. C. , Young R. J. 
Published: May 2005

AbstractIt is demonstrated that Raman spectroscopy can be used to study both the deformation micromechanics of high‐performance aramid polymer fibres and of these fibres in model, single‐fibre epoxy resin matrix composites. It is shown that the peak position of the 1610 cm−1 aramid Raman band shifts to lower frequency under the action of tensile stress or strain due to the macroscopic deformation leading to direct stretching of the polymer molecules. These strain‐induced band shifts can be used to map the distribution of stress or strain along a discontinuous, aramid fibre inside an epoxy resin matrix from which the interfacial shear stress can be calculated. It is shown that the behaviour is consistent with that predicted by the classical shear‐lag analysis. The technique was also used to study the fragmentation process for an aramid fibre in an epoxy resin matrix in which the matrix strain exceeds the failure strain of the fibre. It is further demonstrated that the technique can be used to compare the interfacial properties of aramid fibres where the interfacial shear stress is found to be higher for sized fibres than for those which have been de‐sized.
Estimation of crystallinity in polyethylene by Raman spectroscopy
Authors: Rull F. , Prieto A. C. , Casado J. M. , Sobron F. , Edwards H. G. M. 
Published: May 2005

AbstractThe quantitative determination of crystallinites of polyethylene samples from the analysis of vibrational bands due to δ(CH2) twisting and v(CC) stretching in the Raman spectra between 950 and 1500 cm−1 was assessed. Several methods based on manual resolution of band envelopes and on computer‐derived information using Gaussian and Lorentzian profiles were compared. The major source of error was found to be the estimation of the amorphous and crystalline interphase content, αb. A new method for the determination of sample crystallinity is proposed based on the time‐dependent Fourier transform deconvolution of the spectral region between 950 and 1500 cm−1, which takes into account the baseline corrections and the influence of vibrational band shoulders in this region to obtain consistent values of αa, αb and αc.
Raman studies of sodium fluoroborate single crystals
Authors: Brooker Murray H. 
Published: May 2005

AbstractRaman spectra of oriented single crystals of NaBF4 were measured at 77 and 298 K. The number of bands and the intensities were in excellent agreement with the unit cell group predictions for the known crystal structure, D, Z = 2. The results for the ν1, ν2 and ν4 regions were in excellent agreement with those of Bates [J. Chem. Phys. 55, 489 (1971)]. A recent study by Rajakumar et al. [J. Raman Spectrosc. 23, 75 (1992)] is erroneous. The new measurements permitted the assignment for the Raman bands in the ν3 region. Peaks in the external mode region were very weak because both the Na+ and BF4− ions have spherical symmetry, small polarizabilities and small polarizability derivatives with respect to normal coordinates. Only three weak peaks of the nine predicted external‐modes were observed (88 cm−1, Ag; 110 cm−1, B2g; and 214 cm−1, B2g). Crystals grown from aqueous solution were found to contain water and as much as 0.1% of BF3OH− as a substitutional impurity. Peaks due to the O–H (O–D) stretching vibration were detected in the crystals at 3641 (2688) cm−1 and peaks due to the B–OH (B–OD) stretching vibration were detected as 773 (748) cm−1.
Study of second‐order excitations in α‐iodic acid crystal by means of polariton k‐spectroscopy
Authors: Chekhova M. V. , Penin A. N. 
Published: May 2005

AbstractPolariton spectroscopy was used for studying the dispersion of linear and non‐linear susceptibilities of an α‐iodic acid crystal in the vicinity of second‐order vibrations (wavenumber range 1000–1200 cm−1). The measurements were carried out by means of k‐spectroscopy (spectroscopy in the space of wavenumbers). Here k‐spectroscopy was applied to the resonant case when the polariton frequency lies close to one of the lattice resonances and therefore the angular line shape of scattering is not Lorentzian. To measure the crystal parameters at this frequency, the angular spectrum was analysed and a procedure was developed for angular line shape processing that allows the following values to be calculated: the real and imaginary parts of the dielectric function; the real and imaginary parts of the quadratic susceptibility; and the imaginary part of the cubic susceptibility. All these parameters were measured for an α‐HIO3 crystal in the range containing a few second‐order excitations and also a first‐order vibration of the OH group at 1160 cm−1. The results allow some conjectures to be made regarding the nature of the second‐order excitations.
Study of intact and modified erythrocyte membranes with laser Raman spectroscopy
Authors: Goheen S. C. , Lis L. J. , Kucuk O. , Westerman M. P. , Kauffman J. W. 
Published: May 2005

AbstractRaman spectra of erythrocyte membranes which were intact and erythrocyte membranes which were modified by extrinsic protein extraction procedures were examined. In all cases, there was no apparent correlation between protein extraction and membrane lipid fluidity. The extraction of the band 6 protein by 0.15 M NaCl but not 0.001 M NaDH raised the erythrocyte membrane α‐helical content while the extraction of all extrinsic proteins by 0.1 M NaOH resulted in a decrease in protein α‐helical content. The study shows that either peripheral protein extraction and/or salt solutions can modify the secondary structures of the remaining intrinsic membrane proteins.