bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Fourier 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

Raman 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

The 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

Surface‐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

High‐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

The 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

Surface‐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

Raman 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

IR 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

The 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.
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

Raman 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

An 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

Raman 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

The 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

The 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

Room‐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

Unpolarized 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

Raman 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

Surface‐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

The 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

Resonance‐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

Changes 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

Resonance 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

Intensities 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

Thin 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

Near‐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

Polarized 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

A 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

In 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

A 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

The 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

A 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

Raman (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.
Evidence of quantum‐size effect and electron–phonon interactions in resonance Raman scattering spectra of semiconductor nanocrystals
Authors: Baranov A. V. , Bobovich Ya. S. , Petrov V. I.
Published: May 2005

Raman spectra of II–VI semiconductor nanocrystals embedded in silicate glass matrices with near‐resonance and resonance excitation in the range of electron transitions between size‐quantized energy levels were studied. It is shown that only the transitions with angular momentum l = 0, 2 contribute to the resonance Raman enhancement. The influence of the electron–phonon interaction on the Raman excitation profiles of the LO phonons and elastic vibrations of nanocrystals is analysed. The effect of the matrix on the intensities and frequencies of the low‐frequency Raman (LFR) bands and the possibilities of determining the particle size determination using LFR spectra are discussed.
Evaluation of Raman spectra of solutions with predominantly ionic metal–oxygen interactions
Authors: Bengtsson L. A. , Brooker M. H.
Published: May 2005

The assignment of infrared and Raman bands in the low‐wavenumber (0–500 cm−1) region of molten salts and glasses is complicated by the difference in the selection rules for infrared and Raman activity. Assignments are presented for several molten and glassy nitrates for infrared‐active (antisymmetric metal–oxygen motions) and Raman‐active (symmetrical metal–oxygen motions) vibration modes. Bands associated with monomolecular reorientational motion of the polarizability anisotropy (Raman) and dipole moment (infrared) may also contribute intensity in the 0–200 cm−1 region. A Raman band at about 500 cm−1 which was detected previously in solutions of lithium nitrate in molten (K, Na)NO3 has been reassigned to the glass of the container wall.
Inter‐ and intramolecular force constants of some trihalides of the fifth group in the gas, liquid and solid
Authors: Kondyurin Alexey , Byelousova Nadezhda , Byelousova Sofia , Kozulin Alexander
Published: May 2005

The Raman spectra of trihalides of the Fifth Group, BiCl3, AsCl3, AsBr3, SbBr3 and PCl3, in the gas, liquid and solid were obtained. A normal coordinate analysis was performed. The intermolecular force constants were calculated from variations of the intramolecular force constants of the molecule during the phase transition. The half‐periods of librations in the liquid and lattice frequencies in the crystal were calculated and the lattice spectrum of the crystal was interpreted. It is shown that for a heavy central atom the calculation of intermolecular force constants may be performed in the approximation of a diagonal potential energy matrix. For a light central atom such an approximation may be used only for estimates. In this case the use of a complete potential energy matrix of a molecule is necessary for an accurate calculation.
High‐pressure Raman study of liquid and crystalline CHF2Cl and CHF3
Authors: Wu Y. H. , Onomichi M. , Sasaki S. , Shimizu H.
Published: May 2005

High‐pressure Raman spectra of liquid and crystalline CHF2Cl and CHF3 were measured up to pressures of 15 and 10 GPa, respectively, at 300 K in a gasketed diamond‐anvil cell. The liquid–solid phase transition pressures were determined to be 3.49 GPa for CHF2Cl and 2.46 GPa for CHF3. For both CHF2Cl and CHF3, the wavenumbers of the CH stretching mode ν1 increased rapidly with increasing pressure, and this behaviour was investigated by the theory of reasonance hybrid of the covalent‐bonded and ionic‐bonded structures.
Laser‐induced anisotropy and depolarization ratios
Authors: Dawson Don F. , Koningstein J. A.
Published: May 2005

Monobeam transmission and resonance Raman (RR) experiments were used to study the excited state Sm ← S3(B) spectra and the depolarization ratios, ρn, of the ν2(Cβ–Cβ), A1g, \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 1558{\rm cm}^{ - {\rm 1}} $\end{document}, and δ(pyr), A1g, \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 1643{\rm cm}^{ - {\rm 1}} $\end{document} RR peaks of meso‐tetrakis(N‐methyl‐4‐pyridyl)porphine, H2TMpyP(4), in phosphate buffer (pH 7) at an excitation of λ1 = 422 nm (\documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop {\nu _1 }\limits^ - = 23697{\rm cm}^{ - {\rm 1}} $\end{document}) as a function of pump intensity, I1 (mW), over the range of I1 = 0–5 mW. Three factors, ground state depletion, induced anisotropic density distribution of the ground stage, n1G, and the anisotropic polarized excited‐state absorption effect, are discussed to explain the behaviour of ρn versus I1 for these two peaks. In addition, scattering tensors and experimentally determined depolarization ratios for the \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 1558{\rm cm}^{ - {\rm 1}} $\end{document} and \documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 1643{\rm cm}^{ - {\rm 1}} $\end{document} RR peaks of H2TMpyP(4) at excitations of λ1 = 422, 476.5 and 514.5 nm (\documentclass{article}\pagestyle{empty}\begin{document}$ \Delta \mathop \nu \limits^ - = 23697,{\rm 20986 and 19436 cm}^{ - {\rm 1}} $\end{document}, respectively) are presented. The results seem to imply that a > b, and could be interpreted as the presence of x‐ and y‐splitting of the Soret B band.
Vibrational spectra and structure of perchlorinated metal‐free phthalocyanine and lutetium bisphthalocyanine
Authors: Gobernado‐Mitre I. , Klassen B. , Aroca R. , DeSaja J. A.
Published: May 2005

The infrared and Raman spectra of perchlorinated phthalocyanine (Pc), H2PcCl16, LuPc2Cl32 and the unsymmetrical LuPc2Cl16 are reported. The vibrational data set also include SERRS and the far‐infrared spectra between 100 and 400 cm−1. The vibrational assignment of characteristic wavenumbers was supported by a semi‐empirical calculation using the PM3 Hamiltonian. The H2Pc molecule was used as a reference in the PM3 vibrational calculations. The effect of the chlorine substituents on the optical spectra of the phthalocyanine ring is examined.
Process analysis of electroless nickel deposition baths by Raman spectroscopy
Authors: Gantner E. , Beck M. , Müller H. G. , Steinert D. , Ache H. J.
Published: May 2005

In a test experiment carried out in a small compact electroless plating facility, the concentrations of hypophosphite and phosphite in a nickel deposition bath of the Kanigen type were monitored on‐line with a dispersive Raman spectrometer. From the results, which agreed with off‐line Fourier transform (FT) IR data within ca. 10%, the molar amounts of nickel, hypophosphite and phosphite consumed and formed were calculated and compared with the stoichiometry of the nickel plating process adopted. In addition, nickel bath samples were also measured with an FT Raman spectrometer to compare the performances of both Raman techniques with a view to their application to aqueous solutions.
Contribution of Raman spectroscopy to art and history
Authors: Coupry Claude , Lautié Alain , Revault Madeleine , Dufilho Jérôme
Published: May 2005

Blue pigments used by a 19th century French artist were analysed by Raman microspectrometry. The results are discussed in relation to the painting materials available at that time. This study is connected with an artistic study of the drawings, and allows the artistic and technical aspects of the work of this painter to be compared.
An approach to stone and fresco lichen biodeterioration through Fourier transform Raman microscopic investigation of thallus—substratum encrustations
Authors: Edwards H. G. M. , Edwards K. A. E. , Farwell D. W. , Lewis I. R. , Seaward M. R. D.
Published: May 2005

The Fourier transform Raman spectra of thallus‐substratum interfaces of Xanthoria parietina growing in situ on sandstone and gypsum were obtained for the first time. The presence of small amounts of calcium oxalate in thallus‐substratum interfaces was confirmed spectroscopically and evidence for biodeterioration via lichen metabolic by‐products was also noted. Although the oxalate determined spectroscopically was in good agreement with the results from thermogravimetric measurements there was also spectroscopic evidence for incorporation of stone particles into the lichen encrustation. Comparisons are made with Raman spectroscopic studies of the thalli of the high oxalate‐producing lichen Dirina massiliensis forma sorediata. The Raman spectra Ochrolechia parella growing in association with Xanthoria parietina on maritime sandstone were also recorded and the spatial discrimination of the techniques for these high and low oxalate‐producing lichens was demonstrated.
Non‐traditional methods for obtaining glasses for coatings: A raman and infrared vibrational study
Authors: Bertoluzza A. , Morelli M. A. , Tinti A. , Vasina M.
Published: May 2005

Synthetic methods which provide alternatives to the oxide melting method for the preparation of inorganic glasses are described. These methods were monitored by Raman spectroscopy. The transformation products involved in two main synthetic methods, the ‘sol–gel’ method illustrated here for obtaining glassy SiO2 and the ‘polymeric’ route used for the first time in the preparation of calcium phosphate glasses (CaO.P2O5, calcium metaphosphate; xCaO.P2O5, calcium oligophosphates, where x ≤ 1.6) are characterized and discussed using their Raman spectra. These alternative methods allow vitreous materials to be prepared at moderate temperatures. They can therefore be important in the field of biomaterials for coating metal implants with bioactive glasses and ceramics. The melting method (for glasses) and the plasma spray technique (for ceramics) frequently induce changes of stoichiometry in the coating and also activation of the support material, metal or alloy, resulting in a lack of biocompatibility.
Use of a rapid scanning stigmatic Raman imaging spectrograph in the industrial environment
Authors: Williams K. P. J. , Pitt G. D. , Smith B. J. E. , Whitley A. , Batchelder D. N. , Hayward I. P.
Published: May 2005

Raman spectroscopy is steadily growing in importance in the industrial analytical laboratory. The nature of the equipment, its ease of use and its cost are making the method more acceptable to non‐experts. This paper illustrates the capabilities of a recent commercialized Raman system which fulfils the criteria of ease of use, speed and low cost. The system is designed for Raman microscopy and uses a single spectrograph and CCD detector. The combination provides confocal microscopy, high throughput and optimum sensitivity, to the extent that it only requires the use of a low‐powered laser to provide high‐quality spectral data. The additional feature of direct Raman imaging is seen as being beneficial in the industrial environment in that it provides spatial information over large surface areas quickly and without the need for excessive amounts of data processing. The performance of the instrument is illustrated with applications taken from the industrial environment.
Structural characterization of heterocyclic polymer networks by low‐frequency Raman scattering
Authors: Novikov V. N. , Shebanin A. P. , Azarenkov V. P. , Baibak A. V. , Kramarenko Yu. V. , Privalko V. P.
Published: May 2005

Glassy, heterocyclic copolymers of an epoxy oligomer and hexamethylene diisocyanate were characterized by low‐frequency Raman scattering spectra at room temperature. The experimental data were treated according to the formalism of the theory of inelastic light scattering from fractons to derive structural information in the scale range below 10 nm. The samples studied were shown to behave essentially fractal‐like in the range of characteristic scales (on an order‐of‐magnitude basis) spanning roughly the chain persistence length (ca. 0.7 nm) as a lower structural limit and the network mesh size (ca. 3 nm) as an upper structural limit.
Raman intensity of lattice vibrations in BaCl2 · 2H2O. Many‐body treatment
Authors: Kanesaka Isao , Matsuda Toshiyuki , Niwa Yukie
Published: May 2005

Polarized Raman spectra of BaCl2 · 2H2O and their assignments are reported. The Raman intensity was analysed by means of the pair approximation and the many‐body interaction among induced dipoles. It was found that the many‐body treatment is more quantitative than the pair approximation, although the agreement between the observed and calculated polarized spectra is still incomplete. The difference between the two methods is discussed.
Low‐frequency vibrational spectra of spirocyclic bis(ethane‐1,2‐dithiolato[2‐]‐S,S′‐tin(IV)) and its pyridine and related complexes
Authors: Shamir J. , Starostin P. , Peruzzo V.
Published: May 2005

The Raman and infrared spectra of the tetracoordinated SnS4 compound spirocyclic bis(ethane‐1,2‐dithiolato[2‐]‐S,S'‐tin(IV)) (1) and its related hexacoordinated SnS4L2 complexes with pyridine (2), 2‐(2‐pyridyl)ethylamine (3) and 3‐aminopyrazole (4) were recorded and interpreted. The skeletal vibrations of SnS4 and SnS4N2 were asigned and are discussed. The tetrahedral SnS4 core in 1, which has essentially Td symmetry changes into a square planar with D4h symmetry when coordinating to the N‐donor ligands (2, 3 and 4). This change in structure and symmetry also causes the Sn‐S vibrations to change both in number and wavenumber.
Stimulated Raman and CARS spectroscopy of ν1 and 2ν2 (A1) bands of 12CF4
Authors: Tabyaoui A. , Lavorel B. , Saint‐Loup R. , Rotger M.
Published: May 2005

Two experimental coherent Raman techniques, stimulated Raman and coherent anti‐Stokes Raman spectroscopy (CARS), were employed to study the Raman spectrum of CF4 in the 900 cm−1 region. The stimulated Raman and CARS spectra of the ν1 band of CF4 were recorded at high resolution. The analysis of these spectra enabled some spectroscopic constants of this band to be refined and higher order constants to be determined for the first time. The first high‐resolution CARS spectrum of the 2ν2 (A1) harmonic band is also presented. The rotational transitions of this band up to J = 40 were assigned and the first set of spectroscopic constants for this sub‐level were determined. These results improve our knowledge about the Raman‐allowed vibrational bands of CF4.
New possibilities of overlapping Raman band resolution by methods of CARS spectroscopy
Authors: Fishman A. I. , Mironov S. F.
Published: May 2005

New possibilities for the resolution of Raman bands, provided by polarization‐sensitive CARS in combination with a phase‐mismatching technique, are presented. The use of this combination of techniques allows one to achieve the most informative spectra and resolve the complex structure of inhomogeneously broadened contours. The variation of the resonant/non‐resonant ratio using a phase‐mismatching technique and the special possibilities of polarization CARS spectroscopy in lineshape formation are used. The results of an investigation of a cyclohexane and naphthalene mixture and ofn‐pentane by polarization CARS in combination with a phase‐mismatching technique are presented.
Raman spectra of H2S along the liquid–vapour coexistence curve
Authors: Salmoun Farida , Dubessy Jean , Garrabos Yves , Marsault‐Herail Françoise
Published: May 2005

The ν1 isotropic Raman spectrum of H2S was studied in the dilute gas phase and in the gas and liquid phases along the saturation line (282 ≤ T ≤ Tc = 373.4 K). The temperature and density dependence of the hand shift was analysed assuming a strong resonant transfer due to dipolar interactions. A significant rotational contribution prevents a precise study of the vibrational effects on the asymmetric profile observed at ρ < ρc. A striking critical inhomogeneous broadening is observed as the critical point is approached. Some new results on the v2 isotropic and anisotropic bands of liquid H2S are also presented.
On the difficulty of attributing a fractal signature to low‐frequency Raman spectra of polymers in solution
Authors: Papin R. , Rousseau M. , Durand D. , Nicolai T.
Published: May 2005

Measurements of the low‐frequency Raman spectra (LFRS) (below 100 cm−1) of poly(methyl methacrylates) in solution are reported. The reduced intensity exhibits a power law dependence on the frequency at any concentration and at any conversion rate of the polymerization reaction. Even monomeric liquids such as toluene and methyl methacrylate show such a power law behaviour. The results are compared with recent theories on low‐frequency Raman scattering from fractal structures and suggest that a more careful interpretation of LFRS is needed.
High‐pressure Raman spectra of 3‐methyl‐4‐nitropyridine N‐oxide crystal and pressure‐induced phase transitions
Authors: Zhang Delong , Lan Guoxiang , Hu Shifen , Wang Huafu , Zheng Jimin
Published: May 2005

Raman spectra of a 3‐methyl‐4‐nitropyridine N‐oxide crystal were investigated as a function of pressure in a diamond‐anvil cell up to 93 kbar at room temperature. The crystal shows successive reversible phase transitions at 8, 20 and 60 kbar. Above 60 kbar, all of the external Raman peaks and most of the internal peaks were found to vanish, and this is interpreted as due to polymerization or a crystalline‐to‐amorphous phase transition. On decreasing the pressure, this amorphous state persists to about 20 kbar, and then the spectrum can be recovered completely on decreasing the pressure continuously to ambient, Zallen and Slade's vibrational scaling law was successfully checked.