bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman and infrared spectra of transition metal halide hexahydrates
Authors: Agulló‐Rueda F. , Calleja J. M. , Martini M. , Spinolo G. , Cariati F.
Published: May 2005

The Raman and infrared spectra of NiCl2·6H2O, NiCl2·6D2O, CoCl2·6H2O, CoCl2·6D2O and CoBr2·6H2O single crystals have been measured in the range 3600–30 cm−1 (Raman) and 3800–400 cm−1 (IR). The water internal modes have been best assigned for NiCl2·6H2O, including Fermi resonance effects. The corresponding Raman intensities have been interpreted in terms of the free molecule Raman tensors. Among the lattice vibrations, the metal halide and metal‐water stretchings, and also the librations of the MX2·4H2O octahedra, have been identified and assigned.
Assignment of the forbidden level of the Fermi doublet in the Raman spectrum of CH2Br2
Authors: Bertrán José Fernández , La Serna Torres Boris , Félix Denis Fernández , Lokshin Boris
Published: May 2005

The modified Winther method was used to analyse different assignments of the forbidden level νf in Fermi resonance with the symmetric CH2 stretch ν1 in CH2Br2. Of a set of five differnt combination levels, three were rejected and two plausible assignments are discussed.
Raman and infrared spectra of the all‐trans, 7‐cis, 9‐cis, 13‐cisand 15‐cisisomers of β‐carotene: Key bands distinguishing stretched or terminal‐bent configurations form central‐bent configurations
Authors: Koyama Yasushi , Takatsuka Ichiro , Nakata Munetaka , Tasumi Mitsuo
Published: May 2005

Raman and infrared spectra in the region of 1800‐150 cm−1were recorded for a set ofcis‐transisomers of d̃‐carotene, i.e. the all‐trans, 7‐cis, 9‐cis, 13‐cisand 15‐cisisomers. Spectral comparison revealed Raman and infrared key bands which (1) distinguish stretched or terminal‐bent configurations (all‐trans, 7‐cisand 9‐cis) from central‐bent configurations (13‐cisand 15‐cis), and (2) distinguish unmethylated 7‐cisand 15‐cisconfiguratios. Keybands (1) include Raman bands at 1160 and 1140 cm−1and infrared bands at 825 and 775 cm−1(the intensity varies with the position of thecis‐bend) Key bands (2) include Raman bands at 1274 and 962 cm−1and an infrared band at 741 cm−1(characteristic of the 7‐cisconfiguration), and also a Raman band at 1247 cm−1and an infrared band at 775 cm−1(characteristic of the 15‐cisconfiguration). The normal modes for the key bands were determined by a set of normal coordinate calculations for the isomeric configurations of a simplified model of d̃‐carotene. The key bands were mainly related to the CH in‐plane bendings, coupled with the CC or CC stretching, or to the CH out‐of‐plane wagging vibrations, some of which coupled with the CC torsion.
Raman and far‐infrared spectra of solid carbon tetrabromide
Authors: Hird K. M. , Binbrek O. S. , Anderson A. , Torrie B. H.
Published: May 2005

Raman and far‐infrared spectra of solid CBr4 at temperatures between 20 K and the melting point, 365 K, have been recorded. Low‐temperature results are compared with earlier data and with the predictions of a group theoretical analysis based on the known crystal structure. Isotopic and crystal field effects are distinguished. The number of Raman peaks, especially in the lattice and v3 regions, is compatible with a large unit cell. Certain features are interpreted with the help of recent spectra and calculations on solid SnBr4, Which has a similar unit cell.
Raman and far‐infrared study of the lattice vibrations of methanol
Authors: Anderson A. , Andrews B. , Meiering E. M. , Torrie B. H.
Published: May 2005

Raman and far‐infrared spectra of the lattice vibrations of solid methanol in the ordered α‐phase at 20 K are presented and discussed in terms of the available crystallographic data. Spectra of the deuterated species, CH3OD and CD3OD, have also been recorded to facilitate the assignment of observed peaks. The spectroscopic data are compatible with a centrosymmetric monoclinic unit cell containing four molecules on general sites.
Raman study of a 4‐nitropyridine N‐oxide single crystal. 1—Lattice vibrations
Authors: Joyeux Marc , Jouan Michel , Dao Nguyen Quy
Published: May 2005

High‐quality single crystals of 4‐nitropyridine Noxide (NPO) and 4‐nitropyridine‐d4 N‐oxide (NPO‐d4) of adequate size were prepared by slow recrystallization from an acetone solution. Low‐frequency polarized Raman spectra were recorded in the range 6–200 cm−1. The external vibrations were assigned using group theory and assuming that the libration frequencies are inversely proportional to the square root of the moments of inertia; in the spectra of NPO, the Ag‐B2g components appear at 37–43 cm−1 for Ry and at 51–61 cm−1 for both Tx and Tz, because pseudo‐degeneracy occurs; the B1g ‐B3g components appear at 51–35 cm−1 (Rx), 89–110 cm−1 (Rz) and 152–163 cm−1 (Ty). Two internal vibrations which appear below 200 cm−1 are also assigned: the NO2 twisting at 79 cm−1 and an out‐of plane bending vibration of the N‐oxide and NO2 groups at 121–145 cm−1. As expected, the NPO‐d4 spectra show little difference from that of NPO. The influence of the intermolecular bonds on the frequencies, splittings, widths and intensities of the lines is discussed.
Raman spectroscopic study of Bacillus subtilis extracellular levansucrase: Effect of iron (III) ions on the protein conformation
Authors: Gróf Pál , Aslanian Dimitrina , Chambert Regis
Published: May 2005

Vibrational Raman spectroscopy has been used to study the conformation of the extracellular enzyme levansucrase. Secondary structure analysis by the method of Williams shows 51% β‐sheets, 18% total α‐helical structure (from 7 to 16%) and modifies the environment of the Trp and Phe residues and also more of the CC, CN, CS and CH3 groups.
Spectres de Vibration de l'Acide Furanne 2,3‐Dicarboxylique et de ses Sels de Potassium en Solution Aqueuse
Authors: Cassanas G. , Fabrègue E. , Bardet L.
Published: May 2005

Les spectres Raman et infrarouge de l'acide furanne 2,3‐dicarboxylique et de ses sels de potassium en solution aqueuse ont été étudiés de 100 à 4000 cm−1. Une attribution des fréquences de vibration est proposée. L'état de polarisation des raies Raman montre que le noyau furannique est plan. Les groupements carboxylates de l'ion neutre sont orthogonaux. La liaison H‐intramoléculaire présente dans l'acide et le sel acide à l'état cristallin est assez forte pour subsister en solution aqueuse, les pseudo‐cycles ainsi formés sont contenus dans le plan furannique.
Surface‐enhanced resonance Raman study of avidin–dye interactions: A model for chromophore‐containing proteins
Authors: Ni Fan , Cotton Therese M.
Published: May 2005

Resonance Raman (RR) and surface‐enhanced resonance Raman (SERR) spectroscopy were used to study the behavior of 2‐(4′‐hydroxyphenylazo)benzoic acid (HABA) at different pH values (2.7–11.8) in solution and bound to avidin. Major changes in the RR spectrum of the dye are observed near pH 8.0 and 3.0. These pH values are close to the pKa values for the phenolic and carboxylic acid functional groups of HABA and reflect deprotonation of these groups. In addition, however, tautomeric forms of the dye are possible within each pH range and these can be identified from the characteristic vibrational modes of the azo and hydrazone forms of HABA. Similar changes in the SERR spectrum of HABA were also observed as a function of pH. However, a comparison of the RR and SERR spectra has shown that the tautomeric equilbrium is shifted toward the hydrazone form on the Ag surface compared with the effect in solution.

The RR and SERR spectra of the HABA‐avidin complex are nearly identical and indicative of the hydrazone form of the dye. Hence the complex is not dissociated on the Ag surface. This finding is encouraging with regard to the application of SERR techniques to the study of native proteins containing chromophores.
Surface‐enhanced Raman scattering (SERS) from silver colloids of vanadate, phosphate and arsenate
Authors: Greaves Sarah J. , Griffith William P.
Published: May 2005

Surface‐enhanced Raman scattering (SERS) of [HVO4]2−, [HPO4]2− and [HAsO4]2− has been studied on silver sol in H2O and 2H2O; in H2O the spectra were recorded from pH 3 to 12 with excitation at 488.0, 514.5, 568.2 and 647.1 nm. Considerable enhancement was observed compared with conventional Raman spectra, and deuteriation was observed to have no effect on the band positions in the SER spectra.
Raman scattering and phase transition in orthorhombic crystals of K3Mn(CN)6 and K3Cr(CN)6
Authors: Morioka Y. , Saito A. , Nakagawa I.
Published: May 2005

In the polarized Raman spectra of K3Mn(CN)6 and K3Cr(CN)6, soft modes are observed in both the roomtemperature and the low‐temperature phases. The frequencies of these modes decrease as the transition temperatures [205 K for K3Mn(CN)6 and 215 K for K3Cr(CN)6] are approached from both sides. Unambiguous spectroscopic evidence for the second‐order displacive phase transition was obtained on the basis of the soft mode behaviour in both crystals. High‐pressure Raman spectra of K3Cr(CN)6 were measured up to 35 kbar using a diamond anvil cell. A pressure‐induced phase transition occurs at ca 10 kbar.
Vibrational spectra of pyrazole and deuterium‐substituted analogues
Authors: Majoube Michel
Published: May 2005

Accurate vibrational frequencies are reported for pyrazole and for seven N‐ and C‐deuterated analogues from FT‐IR spectra for the vapour phase at room temperature, diluted CCl4 solutions and polycrystalline solids and from Raman spectra in aqueous solutions. Several frequencies are reported for fundamentals not previously observed in the vapour phase in particular. Assignments were carried out by performing a normal coordinate analysis for in‐plane and out‐of‐plane modes, using either Urey–Bradley or general valence force fields. Great care was taken to determine a refined force constant set which agrees as far as possible with observed isotopic shifts. A detailed description of all the normal modes and atomic displacements for in‐plane modes is given.
The effect of excited state absorption of dimeric chlorophyll on the Raman spectrum of the solvent
Authors: Koningstein J. A.
Published: May 2005

Pulsed laser‐induced Raman spectra of dimeric chlorophyll α in the solvent hexane are reported where the wavelength of the exciting radiation is in resonance with the position of the Soret band of the solute. As a result of the occurrence of effective population saturation of nanosecond‐ and picosecond‐lived S1 and S3 excited states of the dimer, changes take place in the absorption spectrum of the irradiated part of the solution from which Raman emission of the solvent occurs. The intensity of the observed Raman bands of hexane of different shifts are influenced in a different way by the change in the transmission of the medium. A correlation is made of these changes and the said Raman intensities.
High‐pressure phonon behavior in ammonium halides
Authors: Scott J. F.
Published: May 2005

This note comments on the paper ‘High‐pressure Raman Study of Ammonium Halides’ [S.‐J. Jeon, R. F. Porter, and A. L. Ruoff, J. Raman Spectrosc. 19, 179 (1988)]. It is shown that their proposed degeneracy of ν1 and ν3 modes at high pressure is symmetry‐forbidden, but that a near degeneracy follows logically from the Urey–Bradley force model and plausible assumptions about the pressure dependence of force constants.
Resonance CARS spectroscopy of the ground and low‐lying excited electronic states of nickel octaethylporphin solution
Authors: Apanasevich P. A. , Kvach V. V. , Orlovich V. A.
Published: May 2005

Nanosecond time domain transient resonant CARS (RCARS) techniques have been used to investigate photophysical transformations of Ni‐octaethylporphin (Ni‐OEP) in tetrahydrofuran (THF) solution. For the first time the RCARS spectra have been obtained from the short‐lived (280 ps) low‐lying excited electronic state 3B1g, populated under the effect of intense resonant laser pulses. The amplitude‐polarization sensitive techniques of nondegenerate RCARS have been used to perform symmetry species assignments for the Raman‐active vibrational modes in the 1A1g and 3B1g electronic states. Only non‐totally symmetric in‐plane vibrations of the porphyrin skeleton with the b1g, b2g and a2g symmetry species in the D4h point symmetry group show up in the coherent scattering spectra under excitation within the visible Q absorption bands. The character of electronic resonance enhancement for the RCARS process has been studied when the excitation laser frequencies match one‐photon resonances with the frequencies of vibronic transitions between the 3B1g and 3Q″ excited states, and excitation and probing nondegenerate RCARS profiles have been measured for the Raman modes at 1562 and 1627 cm−1. It has been found that the Raman modes intensity in the RCARS spectra from the 3B1g state is borrowed from the Herzberg–Teller scattering when resonances with the 3B1g↔3Q″ transition take place. The data of the saturation degenerate RCARS experiments combined with the numerical analysis of the stationary rate equations for populations of the low‐lying electronic states made it possible to reveal the influence of the resonant radiation intensity on the RCARS efficiency.
Raman spectra of polymerized tetra‐n‐butoxy titanate formed on the surface of several types of silica gel
Authors: Shinoda Takako
Published: May 2005

The Raman spectra of polymerized tetra‐n‐butoxy titanate [pol‐Ti(OBu)4] formed on the surface of five different types of silica gel were studied. Characteristic peaks were found in the range 1000‐1200 cm−1 in all the spectra. The observed Raman spectra showed that the network structure of pol‐Ti(OBu)4 formed on the surface of silica gels, that is, the TiOTiO chain, seems to depend on the properties of the pores of the silica gels. The butoxy groups might be located in a state with a different degree of order. On the other hand, the catalysts which were prepared by using pol‐Ti(OBu)4 showed different photocatalytic activities.
Micro‐Raman analysis of pyrolytic graphite platforms used in atomic absorption spectrometry
Authors: Haley L. V. , Chakrabarti C. L. , Wu Shaole
Published: May 2005

An anisotropic pyrolytic graphite platform used in atomic absorption furnaces was probed with a Raman microscope. Raman spectra of the platform were obtained before heat treatment and after a specified number of thermal cycles. Results are related to the surface crystallite size by comparing the intensity ratio of the 1355 and the 1582 cm−1 bands. Two types of material were identified.
Raman studies of the vibrational dynamics and phase transitions in uranyl nitrate hexahydrate
Authors: Khulbe P. K. , Agarwal Anshu , Raghuvanshi G. S. , Bist H. D. , Hashimoto H. , Kitagawa T. , Little T. S. , Durig J. R.
Published: May 2005

The temperature‐dependent Raman spectra of crystalline uranyl nitrate hexahydrate, UO2(NO3)2 · 6H2O, are reported in the temperature range 15‐290 K. A group theoretically consistent assignment of the bands in terms of UO, NO3− and H2O vibrations is proposed. The temperature‐dependent studies of thermosensitive bands associated with these entities were used to study the previously reported phase transition at 140 ± 5 K and to detect another phase transition at 190 ± 5 K. The latter transition shows up prominently in the temperature‐dependent fluorescence studies and is also accompanied by a sharp increase in the Rayleigh scattering. The transition at 190 ± 5 K is triggered by the dynamics of H2O‐II and UO whereas that at 140 ± 5 K is associated with the dynamics of H2O‐II/NO3−. Both the transitions are of second order.
The origin of two new Raman bands in the surface‐enhanced Raman spectra of pyridine adsorbed on colloidal silver particles
Authors: Feng‐qi Yu , Chun‐ping Zhang , Guang‐yin Zhang
Published: May 2005

Two new broad and strong Raman bands in the surface‐enhanced Raman spectrum of pyridine adsorbed on colloidal silver particles were observed, one near 612 cm−1 and the other near 924 cm−1. It is concluded that these bands are caused by a boron compound in silver sol.
Vibrational analysis of substituted anisoles. II–Transferability of valence force constants
Authors: Lakshmaiah B. , Ramana Rao G.
Published: May 2005

A zero‐order vibrational analysis of the in‐plane vibrations is made for m‐fluoro‐, o‐chloro‐, p‐chloro‐, o‐bromo‐and p‐bromo‐anisole, transferring the force constants from Part I. The observed and calculated frequencies agree with an average error of 13 cm−1, demonstration the transferability of the force field obtained in Part I. On the basis of the calculated potential energy distributions and eigenvectors, several assignments suggested by earlier workers have been revised.
Raman spectra of the tetrabutylammonium diiodoaurate(I) crystal, TBA‐AuI2, without I3− impurity bands
Authors: Ohtsuka Itaru , Nakayama Hideyuki , Ishii Kikujiro
Published: May 2005

Raman spectra of carefully purified (n‐C4H9)4N+ AuI2− (TBA‐AuI2) were measured between 89 K and room temperature. The bands observed around 110 cm−1 in one of the previously reported spectra are ascribed to I3− impurity. Spectra of TBA‐AuI2 and TBA‐I3 were compared, and the principal bands assigned. The resonance Raman effect of I3− makes its Raman bands prominent in the impure TBA‐AuI2 samples. The crystal symmetries of the above two salts at low temperature are briefly discussed.
Non‐resonant background suppression in preresonance CARS spectra of flavin adenine dinucleotide: Demonstration of a background suppression technique using phase mismatching and comparison with the polarization‐sensitive CARS technique
Authors: Scholten T. A. H. M. , Lucassen G. W. , Koelewijn E. , De Mul F. F. M. , Greve J.
Published: May 2005

Polarization‐sensitive CARS spectra of a 5.7 × 10−3 mol dm−3 flavin adenine dinucleotide (FAD) solution were recorded under preresonance conditions at a pump wavelength of 532 nm. The depolarization ratios of the vibrations are shown to be close to the depolarization ratio of the non‐resonant background. This results in a severe reduction of the vibration resonant signal (a factor of 700‐900) in the polarization CARS spectrum, and a poor improvement in the ratio of the resonant signal and the non‐resonant background (<10).

In this context, a non‐resonant background suppression technique is discussed and demonstrated for 5.7 × 10−3 and 1.4 × 10−3 mol dm−3 FAD solutions excited at 532 nm; the non‐resonant susceptibility of the walls of the cuvette, which contains the FAD solution, is used to compensate the non‐resonant signal contribution of the solution. An improvement in the signal‐to‐noise ratio of ca. 50 is achieved at the cost of a factor of 30 in the resonant signal strength. Lorentzian‐shaped spectral bands are obtained, facilitating the determination of band position, width and intensity. Line shape parameters and depolarization ratios for FAD are extracted from the presented spectra by curve fitting. The signal strength and background suppression achieved with these techniques and the resonance CARS technique (at a pump wavelength of 480 nm) are compared and discussed.
Laser Raman and infrared spectra of dipotassium tartrate hemihydrate
Authors: Bhattacharjee R. , Jain Y. S. , Bist H. D.
Published: May 2005

A systematic analysis of the IR and Raman spectra of dipotassium tartrate hemihydrate (K2C4H4O6 · ½H2O) in terms of the standard frequency correlations, deuteration shift and typical nature (with respect to intensity and width) of bands due to different modes is reported. The bands due to the internal modes (excluding some skeletal modes) of the C4H4O ion appear as doublets. For certain modes (e.g. βCH, νC(OH) and δCOO), doublets arise due to interaction between two identical oscillators of two identical groups in COO(HO)HCCH(OH)COO2−, whereas for other modes (e.g. νCH, ν, ν, δCOH, and τCOO) they arise due to crystallographically distinguishable sites for two identical oscillators.
Vibrational spectra of some crown ether complexes of manganese(II) halides
Authors: Li Hongqi , Jiang Tian‐lai , Butler Ian S.
Published: May 2005

The FT‐IR and Raman spectra of six 1 : 1 complexes produced by reaction of 1,4,7,10‐tetraoxacyclotetradecane [12‐crown(4)], 1,4,7,10,13‐pentaoxacyclopentadecane [15‐crown(5)] and 1,4,7,10,13,16‐hexaoxacyclooctadecane [18‐crown(6)] with MnX2 (X = CL, Br) were recorded in the solid state. Vibrational assignements are proposed for the major bands observed in the spectra of these new crown ether complexes, especially the antisymmetric and symmetric COC stretching modes in the 1200–800 cm−1 region and the MnO and MnX stretching vibrations in the region below 400 cm−1. Probable structures of these complexes are also discussed.
Force constant–structure correlations. Part II — carbonhalogen and nitrogenoxygen bonds
Authors: Rao P. Muralidhar , Rao G. Ramana
Published: May 2005

Force constant–structure correlations are presented for CF, CCl, CBr, CI and NO stretching force constants versus bond lengths for a wide variety of compounds.
Raman study of phosphate dimerization in aqueous KH2PO4 solutions using a self‐deconvolution method
Authors: Rull F. , Del Valle A. , Sobron F. , Veintemillas S.
Published: May 2005

A Raman spectroscopic study of aqueous solutions of KH2PO4 as a function of concentration and temperature has been made. Attention is focused on the analysis of the bands arising from the internal modes of the H2PO4− anions. The band profile of these internal modes has been analysed by a Fourier transform self‐deconvolution method which allowed quantitative information about phosphate dimerization to be obtained. The results seem to indicate the existence of two different configurations for the dimers. The association constant for each dimer and their thermodynamic parameters were obtained from the spectroscopic data.
Vibrational spectra of thallium and rubidium phosphotellurates
Authors: Philip Daizy , Aruldhas G.
Published: May 2005

Raman and infrared spectra of Te(OH)6 · 2TlH2PO4 · Tl2HPO4, Te(OH)6 · 2TlH2PO4 and Te(OH)6 · RbH2PO4 · Rb2HPO4 have been recorded and analysed. It is found that hydrogen atoms are strongly bonded to the oxygen atoms of the PO4 tetrahedron forming HPO and H2PO4− ions. Vibrational coupling between the internal modes of HPO and H2PO4− ions is observed in Te(OH)6 · 2TlH2PO4 · Tl2HPO4 and Te(OH)6 · RbH2PO4 · Rb2HPO4. It is found that the TeO6 ion is not occupying a centrosymmetric site in Te(OH)6 · 2TlH2PO4.
Infrared and Raman spectra of bis(fluorocarbonyl) disulphide, [FC(O)]2S2
Authors: Ulic S. E. , Védova C. O. Della , Aymonino P. J.
Published: May 2005

IR data for gaseous, liquid, solid and matrix isolated bis(fluorocarbonyl) disulphide together with the Raman spectrum of the liquid suggest the existence of two planar conformers (I and II) in equilibrium in the gaseous phase and of a planar one and other conformers of undetermined structure in the other neat phases. Wavenumbers reported for the vibration of conformer I are used to calculate an approximated force field.
Etude par Microscopie Raman de la Couche Liquide Située au Contact d'un Cristal en Cours de Dissolution dans sa Solution Mère: Systèmes LiNO3H2O et KNO3H2O
Authors: Koussinsa F. , Bertin F. , Bouix J.
Published: May 2005

The composition of the dissolution layer of LiNO3 and KNO3 crystals in their respective unsaturated mother liquors was studied by Raman microscopy coupled with a multi‐channel acquisition of data. Preliminary examination of homogenous solutions at various concentrations of LiNO3 and KNO3 revealed the existence of individual Raman bands assigned to different solvated species, namely free aquated ions, solvent‐separated ion pairs and/or contact ion pairs. Weak bands due to a small amount of aggregates (LiNO3)n or (KNO3)n were also identified. Spectral parameters of each individual band were calculated. Raman spectra of dissolution layers recorded at different steps of the crystal dissolution revealed considerable reinforcement of aggregates and contact ion pair concentrations compared with that existing in the bulk of the unsaturated mother liquors. The aggregate concentration in the dissolution layer was found to be even higher than that calculated for the corresponding saturated solution. The behaviours of LiNO3 and KNO3 were shown to differ considerably.
Raman studies of NiX2 · 6H2O and FeCl2 · 4H2O
Authors: Cariati F. , Masserano F. , Martini M. , Spinolo G.
Published: May 2005

The Raman spectra of NiCl2 · 6H2O, NiBr2 · 6H2O and FeCl2 · 4H2O single crystals were measured in the range 50–3600 cm−1 at liquid nitrogen temperature. A new assignment of the lattice water translations in the two hexahydrates was made and the metal‐halogen stretching mode was identified. A comparison with recent IR data provided a good characterization of the water libration region. Some proposals for discriminating between the lattice water modes and the coordinated water modes are given for the water internal modes (bending and stretching).
Raman scattering from sapphire fibers
Authors: Jia Weiyi , Yen W. M.
Published: May 2005

An index matching technique for Raman scattering from sapphire fibers is presented; the technique is shown to be effective in suppressing the stray laser background and leads to an improved signal‐to‐noise ratio of the Raman signal. Red shifts of phonon frequencies for bothA1gandEgsymmetry modes were observed under tensile uniaxial stress parallel to thecaxis. The unexpected shifts of theEgmodes may be attributable to effects due to restricted dimensions.
Quenching of stimulated Raman scattering by two‐photon absorption in fuels
Authors: Golombok M. , Bergin F. J. , Pye D. B.
Published: May 2005

There is renewed interest in stimulated Raman scattering in organic liquids because of its potential for droplet sizing in fuel sprays. Contrary to the accepted theories, we observed gain on more than one line simultaneously. In all but the simplest aromatics multiple lines are observed and some expected lines are missing. Absorption spectra suggest that two‐photon absorption could quench the expected Raman signal. A model using real values of two photon cross‐sections shows that in polyaromatics, these are a source loss term for the Raman signal. The resulting disperion in the loss profile leads to gain on the CH stretch rather than the ring breathing mode predicted from the spontaneous spectrum.
Resonance Raman spectra and normal modes of vibration of 2,2′‐bipyridine anion radicals
Authors: Danzer Gerald D. , Golus Janusz A. , Strommen Dennis P. , Kincaid James R.
Published: May 2005

The resonance Raman spectra of the lithium complexes of the 2,2′‐bipyridine anion radical and five isotopically labeled analogues, including the 15N‐labeled species, are reported. All of the fundamental modes of vibration, excluding the CH stretching and several low‐frequency modes, have been identified. Care must be taken to avoid contamination of the sample with the dianion Li2bpy. In order to eliminate possible misassignment of bands to traces of Li2bpy, the spectra of the latter species were also investigated. The assignments of the vibrational frequencies to the fundamental modes of Libpy are supported by a normal coordinate calculation and the structural implications of the vibrational frequency shifts, relative to the neutral parent, are discussed.
Fourier transform Raman and infrared vibrational study of diazepam and four closely related 1,4‐benzodiazepines
Authors: Neville G. A. , Shurvell H. F.
Published: May 2005

Fourier transform Raman and infrared spectra have been recorded of diazepam (7‐chloro‐1,3‐dihydro‐1‐methyl‐5‐phenyl‐2H‐1,4‐benzodiazepin‐2‐one) and four compounds with closely related structures. These compounds are all 7‐chloro‐1,3‐dihydro‐5‐phenyl‐2H‐1,4‐benzodiazepin‐2‐ones and differ only in the nature of the substituent (R) at N‐1. The five compounds are nordazepam (R  H), diazepam (R  CH3), pinazepam (R  CH2 CCH), halazepam (R  CH2 CF3) and prazepam (R  cyclopropylmethyl). Prominent features of the infrared and Raman spectra have been assigned to functional groups of the parent structure and the substituent groups. The spectra of nordazepam suggest that the compound exists as a centrosymmetric cyclic dimer in the solid state. Complete tabulations of the observed wavenumbers of the five molecules are given. The spectra provide a means of identification of these drugs.
Surface‐enhanced Raman spectroscopy of biomolecules. Part II. Application of short‐ and long‐range components of SERS to the study of the structure and function of membrane proteins
Authors: Nabiev I. R. , Chumanov G. D. , Efremov R. G.
Published: May 2005

Surface enhanced Raman (SER) spectra of bacteriorhodopsin (BRh) in the purple membranes of Halobacterium halobium, rhodopsin (Rh) in the photoreceptor dises of rod outer segments and complexes of Rh with monoclonal antibodies and photoreceptor dises closed with the cytoplasmic surface inwards were analysed. After adsorption of the membrane proteins on silver electrodes treated via an oxidation‐reduction cycle (ORC) and on unaggregated silver hydrosols with a mean particle diameter about 15 nm, the short‐range enhancement mechanisms was shown; it may be used to study the topography of the membrane‐bound complexes. In this case adsorption prevents photoinduced conformational transitions of the pigments. If the BRh or Rh molecules are adsorbed on partially aggregated hydrosols with a characteristic particle size aout 100 nm or on “smooth” (i.e. not roughened by the ORC) electrodes, the SERS mechanism has a longer range character. Hence it is possible to detect SER spectra which are similar to those obtained in solution but at concentrations two to three orders of magnitude lower. Under such conditions adsorption does not influence photochemical transformations of bacterial and visual rhodopsins. The potential variation on the “smooth” electrode near the zero charge for silver is accompanied by accumulation of K610, the kinetic intermediate of the BRh photocycle. At the same time, the content of the main form, BRh570, decreases.
Investigations of vibronic transitions by resonance CARS
Authors: Kircheva P. P. , Simeonov S. D.
Published: May 2005

The influence of thermally excited vibrations on vibronic spectra (absorption, CARS excitation profile and resonance background) has been modelled for polyatomic molecules in solution. It is shown that for a model describing some polymethine compounds, the spectra depend only slightly on temperature except in the case of a resonance background and an excitation profile of vibrations with a relatively high value of the origin shift parameter (Δ > 1). The investigations of low‐frequency vibrations by resonance CARS to giving information about some molecular parameters is proposed.
Raman spectral studies of dehydration of Sr(BrO3)2 · H2O
Authors: Srinivasan T. K. K. , Devanathan T.
Published: May 2005

Raman spectra of single‐crystal Sr(BrO3)2 · H2O were examined at 298 and 356 K from the fully hydrated to the totally anhydrous state. The Raman spectrum of the anhydrous compound, when compared with that of the hydrate, showed significant alterations in both the internal and lattice regions. The changes in the ν2–ν4 region revealed the existence of non‐equivalent BrO3− groups in the anhydrous compound. It is inferred from a relative comparison of the Raman and infrared spectra in the lattice region and thermal motion analysis that largeamplitude motions are operative for the BrO3− in the anhydrous compound.
Raman and infrared spectra, conformational stability and vibrational assignment for 1,1,1‐trifluoro‐2‐methoxypropane
Authors: Durig J. R. , Larsen R. A. , Kelley Rosalyn , Sun Feng‐Yi , Li Ying‐Sing
Published: May 2005

The Raman spectra of gaseous, liquid and solid 1, 1, 1‐trifluoro‐2‐methoxypropane, CF3(CH3)CHOCH3, and the corresponding methoxy‐d3 isotope, CF3(CH3)CHOCD3, together with the infrared spectra of the gases and solids were recorded from 3500 to 30 cm−1. A comparison of the vibrational spectra obtained for the fluid phases with those obtained for the amorphous and annealed solids indicates the predominance of two conformers in the fluid phases at ambient temperature. Owing to possible steric hindrance, it is suggested that the most stable conformer is the gauche‐2 form, which has the methoxy group trans with respect to the carbon‐carbon bond of the perfluoromethyl group. This conformer is the one present in the solid. The other conformer in appreciable abundance in the fluid states is probably the gauche‐1 form, which has the methoxy group trans to the carbon‐carbon bond of the methyl group. From a temperature study of the Raman spectrum of the liquid, the enthalpy difference between these conformers was determined to be 180 ± 100 cm−1 (515 ± 286 cal mol−1). The asymmetric torsional frequencies for the gauche‐2 and gauche‐1 conformers are 93 and 53 cm−1, respectively, and from these data and the enthalpy difference the values for the potential constants governing the internal rotation have been estimated. The normal modes have been assigned based on group frequencies, isotopic shifts, depolarization values and infrared band contours. The barrier to internal rotation of the methyl group is calculated to be 1275 cm−1 (3.65 kcal mol−1) from the torsional frequency of 234 cm−1 of the solid.
Influence of addition of potassium chloride to silver colloids
Authors: Zhang P. X. , Fang Y. , Wang W. N. , Ni D. H. , Fu S. Y.
Published: May 2005

The influence on silver colloids of the addition of KCI was directly investigated by means of transmission electron microscopy (TEM). It was found that the particle size increased and the surfaces of the crystal particles of the silver became covered with an overlayer. Additionally, the pattern of aggregation was found to be chain‐like. These changes were very different from those caused by adding pyridine. The mechanism affecting the colloid and the intensity of the surface‐enhanced Raman scattering signals of adsorbed molecules on adding KCl to silver colloid is discussed.
Analysis of small samples using fourier transform Raman spectroscopy
Authors: Williams K. P. J.
Published: May 2005

The fourier transform (FT) Raman method, the main technique for overcoming background fluorescence in Raman spectroscopy, was applied to small samples which proved difficult to study using visible laser Raman methods. Various examples are given and the minimum sample size for FT‐Raman spectroscopy has been shown to be in the microgram range.
Low‐frequency Raman and infrared scatterings in single crystals of sodium acid phthalate, NaC8H5O4 · ½H2O
Authors: Miniewicz A. , Lefebvre J. , Fontaine H. , Marqueton Y.
Published: May 2005

Polarized, low frequency (5–400 cm−1) Raman scattering spectra in single crystals of sodium acid phthalate (NaAP) were measured at 295 and 115 K. Similarly, infrared scattering measurements were performed by FTIR reflection and transmission techniques at room temperature. Symmetry assignments and band descriptions consistent with the crystal structure of NaAP are reported. The effects of crystal anisotropy on polar phonons and LOTO splittings were observed and are commented upon.
Behaviour of the high‐frequency component of the OH stretching Raman band of water in H2O2H2O mixtures
Authors: Zhelyaskov V. , Georgiev G. , Nickolov Zh. , Miteva N.
Published: May 2005

The Fourier deconvolution technique was applied to the analysis of Raman OH stretching spectra in H2O2H2O mixtures. An intensity decrease and a low‐frequency shift of the resolved high‐frequency component at 3635 cm−1 was established and can be used in the elucidation of physical models explaining the existence of weakly hydrogen‐bonded OH oscillators in liquid water.
Second spectral moment of vibrational hyper‐Raman and hyper‐Rayleigh spectra
Authors: Bancewicz T. , Kielich S.
Published: May 2005

Equations for the second spectral moment of vibrational hyper‐Raman and hyper‐Rayleigh spectra are derived. It is shown that owing to the simultaneous dependence of the hyper‐Raman and hyper‐Rayleigh intensities on the irreducible spherical first‐ and third‐rank hyperpolarizability tensors, both the unnormalized and the normalized second moments of both the above types of scattering are geometry dependent. However, for some molecular symmetries and for some molecular vibrations, the irreducible first‐rank hyperpolarizability tensor vanishes; then the normalized second spectral moment of the second‐harmonically scattered rediation is independent of the scattering geometry, as in the linear case.
Resonance Raman scattering in multi‐mode Jahn–Teller systems
Authors: Hizhnyakov V. , Tehver I. , Zavt G.
Published: May 2005

In multi‐mode systems with a degenerate excited electronic state, resonance Raman scattering (RRS) can be effectively examined by the Fourier amplitude formalism, where RRS amplitudes are described by the Fourier transforms of phonon correlation functions. Model calculations of REPs of both totally and non‐totally symmetric modes have been carried out in the case of a weak vibronic coupling to off‐diagonal modes. The calculations demonstrate a high sensitivity of RRS to the Jahn–Teller effect for the vibraitons of both the discrete and the continuum spectrum.
Surface‐enhanced Raman scattering of cytosine and its derivatives in silver sol
Authors: Lee Heewon , Suh Se Won , Kim Myung Soo
Published: May 2005

Surface‐enhanced Raman scattering of cytosine, cytidine, 2′‐deoxycytidine, and cytidine 5′‐monophosphate (5′‐rCMP) in silver sol was investigated. Cytosine seemed to adsorb on the silver surface as the neutral form. With cytosine and 5′‐rCMP, their orientations with respect to the surface changed from a horizontal to a perpendicular position as the surface concentration increased. Similar reorientation was induced for 5′‐rCMP by an increase in phosphoric acid concentration. Adsorption of the cytosine moiety on the surface seemed to occur through the π system of the ring in the horizontal position and through the lone pair of electrons on the N‐3 atom in the perpendicular position.
Polymerization of nitro compounds on silver surfaces during surface‐enhanced Raman scattering
Authors: Tsai W. H. , Boerio F. J. , Clarson S. J. , Montaudo Giorgio
Published: May 2005

Surface‐enhanced Raman scattering (SERS) was observed from thin films formed by 1,4‐ and 1,3‐dinitrobenzene (DNB) spin‐coated onto silver island films from dilute solutions. During laser irradiation of 1,4‐DNB films on silver substrates at relatively high laser powers, new bands appeared near 1152, 1350, 1412 and 1460 cm−1 and bands near 1118, 1358 and 1372 cm−1 decreased in inensity. A band near 1598 cm−1 shifted to near 1605 cm−1. The bands near 1152 and 1412 cm−1 were assigned to stretching modes of ϕN andNN bonds of azo compounds, respectively, indicating that polymerization of 1,4‐DNB had occurred. The extent of polymerization was greatest when the surface coverage of adsorbed 1,4‐DNB was greatest and when the SERS experiments were carried out in a nitrogen atmosphere, indicating that reducing conditions were required for the polymerization. No polymerization was observed for 1,3‐DNB under similar circumstances. The difference was attributed to orientation of the adsorbed species. It was concluded that 1,4‐DNB was adsorbed with a horizontal configuration in which the aromatic rings were parallel to the substrate surface and both nitro groups were in contact with the surface while 1,3‐DNB was adsorbed with a vertical configuration in which the rings were perpendicular to the surface and only one nitro group was in contact with the surface.
Surface‐enhanced Raman spectroscopy of biomolecules. Part III.—Determination of the local destabilization regions in the double helix
Authors: Nabiev Igor R. , Sokolov Konstantin V. , Voloshin Oleg N.
Published: May 2005

Surface‐enhanced Raman (SER) spectra of nucleotides, calf thymus DNA and plasmid pAO 3 in the supercoiled and relaxed conformations adsorbed on colloidal silver were analysed. Two different techniques were used for the preparation of the silver hydrosol. All the compounds were adsorbed on the standard hydrosol with very low specificity with respect to the chemical nature of the adsorbate. ‘Activation’ of the standard hydrosol by Cl− ions induced adsorption sites highly specific to the adenine nucleotides. It was demonstrated that recording of highresolution SER spectra of nucleic acids and their components at 10−13 g is possible and that ‘activation’ of the silver hydrosol permits the selective detection of the sites of destabilization of double‐stranded helices and identification of the nucleotides in these sites.
Conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment of propionyl fluoride
Authors: Durig J. R. , Guirgis G. A. , Phan H. V.
Published: May 2005

The Raman (3100–10 cm−1) and infrared spectra (3100–30 cm−1) of propionyl fluoride in the gas and solid phases were recorded. Additionally, the Raman spectrum of the liquid and the qualitative depolarization ratios were also obtained. From these data a complete vibrational assignment is proposed for an s‐trans/gauche equilibrium in the gas and liquid phases, with the s‐trans conformer (the CH3 moiety is s‐trans to the fluorine atom) being the most stable form in both of these physical states and the only form present in the solid phase. A new potential function has been calculated from the data previously obtained from the far‐infrared spectrum of the gas. The determined potential coefficients are V1 = 328 ± 6, V2 = 239 ± 8, V3 = 417 ± 3, V4 = 30 ± 3 and V6 = −4 ± 2 cm−1, and values of 720 ± 8 (2.06 ± 0.02 kcal mol−1) and 297 ± 9 cm−1 (0.85 ± 0.02 kcal mol−1), respectively, were obtained for the s‐trans to gauche and gauche to gauche barriers to internal rotation of the CFO moiety. Additionally, the s‐trans conformer was determined to be 448 ± 17 cm−1 (1.28 ± 0.05 kcal mol−1) more stable than the gauche conformer. From the study of the Raman spectrum obtaind for the liquid at different temperatures, a value of 267 ± 12 cm−1 (0.76 ± 0.03 kcal mol−1) was determined for ΔH between the two conformers. The structural parameters, conformational stabilities, barriers to internal rotation and fundamental vibrational frequencies which were determined experimentally are compared with those obtained from ab initio Hartree‐Fock gradient calculations employing both the RHF/3‐21G and RHF/6–31G* basis sets, and with the corresponding quantities obtained for some similar molecules.
Hypersound velocities in tris‐sarcosine calcium chloride at room temperature
Authors: Prieto C.
Published: May 2005

Brillouin scattering at room temperature has been used to determine the elastic constant tensor for the trissarcosine calcium chloride (TSCC): the frequency used was near 18 GHz. The sound velocity polar diagrams show an interesting behaviour: the quasi‐longitudinal and the quasi‐transversal branches are degenerate for a propagation direction inside the (010) plane.
Micro‐Raman spectra of crystalline uridine at high pressures
Authors: Huang Yining , Butler Ian S.
Published: May 2005

Micro‐Raman spectra of crystalline uridine were obtained at room temperature and at pressures approaching 40 kbar with the aid of a diamond‐anvil cell. There is evidence for a phase transition at about 12 kbar which is probably associated with changes in the hydrogen‐bonding interactions between the two molecules present in the unit cell.
Raman and far‐infrared study of crystalline 1,1‐dichloroethylene, CH2CCl2 and CD2CCl2
Authors: Prystupa D. A. , Anderson A. , Torrie B. H.
Published: May 2005

Far infrared spectra (30–200 cm−1) and Raman spectra (20–3200 cm−1) of crystalline CH2CCl2 and CD2CCl2 at 20 and 80 K are reported. The lattice spectra contain 29 Raman‐ and 15 infrared‐active modes, which are assigned on the basis of their isotopic frequency shifts. Crystal field splittings and shifts of internal modes are examined in detail. A centrosymmetric unit cell containing at least eight molecules is indicated by these spectra.
Raman and infrared study of crystalline methyltrichlorosilane
Authors: Prystupa D. A. , Anderson A. , Lefebvre J. H. , Torrie B. H.
Published: May 2005

The Raman and infrared spectra between 30 and 3000 cm−1 of a new crystalline phase of methyltrichlorosilane, CH3SiCl3, at 20 K are reported. The spectra are consistent with a non‐centrosymmetric crystal structure with at least four molecules per unit cell. A glassy phase is also detected.
Vibrational study of crystal phase transitions in pyrrole (C4H5N) and C4D5N
Authors: Lautie A. , Romain F.
Published: May 2005

Infrared and Raman spectra of crystalline pyrrole and pyrrole‐d5 were recorded in the range 5–4000 cm−1. The behaviour of internal and external modes was studied as a function of temperature between 200 and 5 K. Two phase transitions were observed at 67 and 30 K and their mechanism is discussed. For the incommensurate phase, between 67 and 30 K, the amplitude and phase modes were identified at about 20 and 10 cm−1, respectively; for the first, a critical exponent of 0.30 was determined. No evidence of NH …︁ π hydrogen bond participation in the transitions has been detected.
Distortion‐induced intensity of Raman modes of molecular units in different crystal orientations
Authors: Bhattacharjee R.
Published: May 2005

Using the principles of the theory of distortion‐induced activity of forbidden Raman modes of molecular units in differnt crystal orientations and the theory of distortion‐induced Raman intensities of different modes of molecular units adsorbed onto metal surfaces, the distortion‐induced intensities of different Raman modes of molecular units in differnt crystal orientations is discussed. An example of the intensities of ν1s, ν2s, ν3s and ν4s (where s represents the SO ion) of (NH4)2SO4 [D] single crystal in Ag, B1g, B2g B3g orientations is discussed to demonstrate the usefulness of the results of these theories.
Raman spectroscopic study of complex formation between dimethyl sulfoxide and chloroform
Authors: Rintoul L. , Shurvell H. F.
Published: May 2005

The sulfur‐oxygen stretching region of dimethyl sulfoxide (DMSO) in chloroform solutions has been studied by means of Raman spectroscopy. The number of linearly independent spectral components in the SO stretching band envelope was determined to be four by factor analysis. The overall band envelope was fitted with five Lorentz‐Gaussian functions using a non‐linear least‐squares procedure. The results were found to be consistent with the formation of 1:1 and 1:2 DMSOCHCl3 complexes, which give rise to bands centered at 1054 and 1032 cm−1, respectively. Equilibrium constants could not be calculated because of coincidences between bands of pure DMSO and bands due to the two DMSOCHCl3 complexes. The spectrum of a 0.0065 mole fraction DMSO solution in chloroform indicates a nearly complete conversion of DMSO species to the 1:1 chloroform complexes at this concentration. A very weak Raman band at 1018 cm−1 and an IR band of medium intensity at 1017 cm−1 in the spectra of pure DMSO were detected by the use of band‐fitting techniques. The assignments of these bands and the other bands in the methyl rocking region are discussed.
Ultraviolet resonance Raman spectroscopy of X—Proline bonds: A new marker band of hydrogen bonding at the imide CO site
Authors: Takeuchi Hideo , Harada Issei
Published: May 2005

UV resonance Raman spectra of proline‐containing peptides were measured in order to study the effects of transcis isomerization and hydrogen bonding on the imide II [C(O)‐N stretch] vibration of the X‐Pro bond. The isomerization does not affect the imide II frequency noticeably but the hydrogen bonding at the CO site increases the frequency markedly, which varies from ca. 1445 cm−1 in the non‐hydrogen‐bonding state to ca. 1485 cm−1 in a strongly hydrogen‐bonded state (from 1440 to 1465 cm−1 for Pro‐Pro linkages). The large upward frequency shift on hydrogen bonding indicates that the imide II frequency can serve as a structural marker of X‐Pro bonds, particularly in distinguishing bent peptide backbones involving different hydrogen bonding states of the imide CO group. Applications of this marker band to structural studies of proline‐containing oligopeptides are demonstrated for tuftsin, bradykinin and gramicidin S.