bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectra and structure of small‐ring compounds. LXII—Raman and infrared spectra, conformational stability, vibrational assignment and ab initio calculations of cyclopropylmethyltrifluorosilane
Authors: Little T. S. , Vaughn C. A. , Zhu Xiang , Dakkouri M. , Durig J. R. 
Published: May 2005

AbstractThe Raman (3500–20 cm−1) and infrared (3500–50 cm−1) spectra of gaseous and solid cyclo‐propylmethyltrifluorosilane, c‐C3H5CH2SiF3, were recorded. Additionally, the Raman spectrum of the liquid was obtained along with qualitative depolarization values. The spectra of the gas and liquid were interpreted on the basis of the predominance of a conformation having a gauche structure and this form exists exclusively in the solid. Spectral evidence to support the existence of a higher energy cis conformer where the SiF3 group is cis to the cyclopropyl ring is observed in the Raman spectra of the gas and liquid. From studies of the Raman spectra at various temperatures, the conformational enthalpy difference was determined to be 490 ± 122 cm−1 (1.4 ± 0.35 kcal mol−1) and 548 ± 110 cm−1 (1.57 ± 0.32 kcal mol−1) (1 kcal = 4.184 kJ) for the gas and liquid, respectively. The cyclopropyl torsion was observed as a weak infrared band centered at 77 cm−1 in the spectrum of the gas. A complete assignment of the normal vibrational modes is provided. Ab initio calculations utilizing the RHF/6‐31G* and MP2/6‐31G* basis sets are consistent with the gauche rotamer lying 554 cm−1 (1.6 kcal mol−1) and 296 cm−1 (0.85 kcal mol−1), respectively, lower in energy than the cis conformation. It is estimated that there is only 4–10% of the higher energy conformer present in the vapor at ambient temperature. Optimized structural parameters were obtained for both conformers with both basis sets and the results should provide good starting parameters for the analysis of the electron diffraction data. The force field obtained with the RHF/6–31G* basis set was used to perform a normal coordinate analysis. These results are compared with corresponding quantities for some similar molecules.
Raman and infrared spectra, conformational stability, barrier to internal rotation, and ab initio calculations for 1,1‐dichloromethyl methyl ether
Authors: Stidham Howard D. , Vlaservich A. Charla , Hsu David Y. , Guirgis Gamil A. , Durig J. R. 
Published: May 2005

AbstractThe Raman (3200–30 cm−1) and infrared (3200–50 cm−1) spectra of 1,1‐dichloromethyl methyl ether are reported for the gas, liquid, amorphous solid and annealed polycrystalline solid. These spectral data were interpreted on the basis that in the fluid phases there is a mixture of trans and gauche conformers but only the trans conformer remains in the annealed solid. From the temperature‐dependent relative intensity of Raman bands at 379 and 427 cm−1 in the liquid, an enthalpy difference of 656 ± 84 cm−1 (1.88 ± 0.24 kcal mol−1 or 7.85 ± 1.0 kJ mol−1) was obtained with the trans conformer the more stable form. Complete vibrational assignments are made for the much more abundant trans form, and a number of fundamentals are assigned for the gauche conformer with the aid of ab initio computations made with the 3–21G and 6–31G* basis sets. The harmonic force fields obtained using the 3–21G basis set are reported for both conformers together with scaled and unscaled wavenumbers and the accompanying potential energy distributions. The results are compared with the corresponding quantities obtained for some similar molecules.
Raman study of a phase transition in solid trifluoroiodomethane
Authors: Beardsall A. J. , Schlueter S. A. , Anderson A. 
Published: May 2005

AbstractRaman spectra of solid trifluoroiodomethane are reported for both the lattice and internal mode regions for samples at temperatures between 12 and 130 K. A solid‐state phase transition at about 115 K is confirmed. Above this temperature, the spectra are characteristic of a disordered or highly anharmonic solid. At low temperatures, the spectra are compatible with an ordered, harmonic molecular crystal with a unit cell containing at least four molecules. Plausible assignments of all observed spectroscopic features are proposed.
Vibrational spectroscopic study of zinc tris(thiourea) sulphate, a new organometallic non‐linear optical crystal
Authors: Venkataramanan V. , Srinivasan M. R. , Bhat H. L. 
Published: May 2005

AbstractVibrational spectra of zinc tris(thiourea) sulphate (ZTS), a new semiorganic non‐linear optical crystal, were recorded to determine the symmetries of molecular vibrations. The observed Raman and infrared bands are assigned to molecular vibrations of thiourea, sulphate groups and Zn(thiourea)3SO4 tetrahedra. The Raman spectra are interpreted in the light of crystal structure data. Modifications in the IR spectra of thiourea due to metal complexations are discussed.
Vibrational spectra of [15N]glutamic acid and [2H4]glutamic acid
Authors: Navarrete J. T. López , Hernández V. , Ramírez F. J. 
Published: May 2005

AbstractThe infrared and Raman spectra of L‐glutamic acid, [2H4]‐L‐glutamic acid and [15N]‐L‐glutamic acid as solid samples were measured. The data obtained were used to propose a general assignment of the fundamental vibrational modes on the basis of the measured isotopic shifts and correlations with previous data reported for aspartic acid and other amino acids and related molecules.
Resonance Raman spectra of the O2 adducts of cobalt ‘picket‐fence’ porphyrin complexes of 3, 5‐dichloropyridine
Authors: Proniewicz Leonard M. , Golus Janusz , Nakamoto Kazuo , Kincaid James R. 
Published: May 2005

AbstractResonance Raman spectra are reported for the 16O2 and 18O2 adducts of cobalt porphyrin complexes with 3,5‐dichloropyridine (DCP) for three different ‘picket‐fence’ porphyrins. It is shown that the v(O—O) effectively couples with an internal mode of DCP giving rise to complicated spectral patterns. These spectral patterns were carefully analyzed to reveal the inherent wavenumbers of v(O—O) which are shown to vary as expected, given the known relative hydrogen bonding capabilities of the three different superstructured porphyrins.
Raman spectroscopic study of fourteen positional isomers of carboxylic acid esters with seventeen skeletal atoms
Authors: Mido Yoshiyuki , Kimura Tatsuo , Ishida Yoshiko , Matsuura Hiroatsu 
Published: May 2005

AbstractThe Raman spectra of 14 positional isomers of carboxylic acids esters with 17 skeletal atoms, CH3(CH2)m−1COO(CH2)n−1CH3(CmCOOCn) with m + n = 15 and m = 1—14, have been measured in the crystalline state at liquid nitrogen temperature. The relationship between the observed wavenumbers of the characteristic bands and the positions of the —C(=O)—O— group in the molecular chain was examined. All of the positional isomers of CmCOOCn with m + n = 15 exhibit a strong LAM‐1 band in the region between 147 and 136 cm−1. The LAM‐1 wavenumbers for the isomers which have the —C(=O)—O— group almost in the middle of the molecular chain are slightly higher (147—143 cm−1) than those for the isomers which have the same group almost at the end of the chain. In order to elucidate the observed LAM‐1 wavenumbers, the Raman spectra of two homologous series of esters, C5COOCn and C6COOCn, were examined. All isomers of CmCOOCn give a strong band at about 1135 cm−1 assignable to the k = 1 mode of the C—C stretching vibrations. Some of the isomers give an additional k = 1 band at about 1125 cm−1. The isomers of CmCOOCn, which exhibit the two k = 1 bands, have the —C(=O)—O— group almost in the middle of the molecular chain, and appear to give the LAM‐1 band at the higher wavenumbers. In the crystalline state all of the esters examined take the all‐trans conformation with the —C(=O)—O— group part incorporated.
Raman spectra of n‐butanoate ion (d0, 2‐d2, 3‐d2 and 4‐d3) in aqueous solution. Assignment to the conformers
Authors: Raada N. , Gaufrès R. , Bribes J.‐L. , Maillols J. , Montginoul C. 
Published: May 2005

AbstractA vibrational study of the n‐butanoate ion in aqueous solution was undertaken. Four isotopic species (d0, 2‐d2, 3‐d2 and 4‐d3) of the potassium n‐butanoate were studied. A normal coordinate analysis was carried out, using the force fields established for the propanoate ion and for n‐butane, according to the moiety of the n‐butanoate ion being considered. The Raman spectra of aqueous solutions (2.5 M) and of the solid phases are described. A spectral subtraction method, which is discussed, was used in order to assign the observed bands, on the basis of their behaviour with temperature increase, to the trans and the gauche conformers. Finally, an assignment is proposed, taking into account all the experimental observations, for the four isotopic species, except in the δ(CH), v(CD) and v(CH) ranges.
Resonance Raman spectroscopy of bis(isomaleonitriledithiolato)nickelate(II) as a probe to the chromophore extension
Authors: De Mello M. T. S. , Ribeiro M. C. C. , Santos P. S. 
Published: May 2005

AbstractThe resonance Raman spectrum of bis(isomaleonitriledithiolato)nickelate(II) was investigated in order to assess the extent of the electronic delocalization within the chromophore. Previous results for the isomeric species bis(maleonitriledithiolato)nickelate(II) indicated an extensive delocalization involving the Ni—S, C=C and C≡N bonds. The present results conclusively indicate that in the case of [Ni(imnt)]2− the delocalization is much more restricted, which is in line with a previous suggestion concerning the marked difference in the two species concerning the stability towards oxidation. The resonance Raman results show a very pronounced enhancement of the v(Ni—S) and δ(ring) modes via the Albrech's A term, which is supported by the simulations undertaken using the transform method and the time‐dependent approach.
Structure of some arylazophenols and arylazonaphthols in the solid state: A resonance Raman study
Authors: Bajpai P. K. , Pal Biswajit , Baul T. S. Basu 
Published: May 2005

AbstractA resonance Raman study of (2‐hydroxy‐5‐metheylphenylazo)benzene and (2‐hydroxynaphthylazo)benzene and their derivatives is presented. The characteristic modes in the azo and hydrazone forms are identified. Structures for both types of compounds in the solid state are proposed. It is shown that hydroxy substitution at the ortho position forms a hydrogen bond with the nitrogen atom of the azo group in arylazophenols. The effect of ring substitution on the characteristic modes is also discussed.
Vibrational molecular force field of model compounds with biological interest VI—harmonic dynamic of methyl α‐D‐mannoside in the crystalline state
Authors: Kouach‐Alix I. , Dauchez M. , Sekkal M. , Vergoten G. 
Published: May 2005

AbstractA Urey—Bradley—Shimanouchi modified force field was used to establish a set of parameters for the potential energy function of methyl α‐D‐mannopyranoside, which is contained in the glycan part of glycoproteins. This force field was combined with an intermolecular potential energy function which includes Van der Waals interactions, electrostatic terms and an explicit hydrogen bond function. Raman and IR spectra of methyl α‐D‐mannopyranoside are presented. Good agreement was obtained between the observed and calculated vibration wavenumbers. The assignments of the observed vibration bands are compared with those in previous studies.
Raman intensity of K2MCl6 (M = Pt or Sn) by the modified many‐body model
Authors: Kanesaka Isao , Matsuda Toshiyuki , Morioka Yoshiyuki 
Published: May 2005

AbstractThe Raman intensity of K2MCl6 (M = Pt or Sn) was analysed using the many‐body model, which treats the interaction among induced dipoles. The result was satisfactory of K2PtCl6, but not for K2SnCl6. Some improvements to the model were made. It is concluded that the preferred method for analysing simultaneously the Raman intensity of internal and external modes in crystals is to use the many‐body model together with the ordinary method for covalent and/or coordination bonds.
Solvation of chloride ions in alcohols
Authors: Honshoh Masami , Kanno Hitoshi , Ueda Toyotoshi 
Published: May 2005

AbstractRaman OH stretching spectra were measured for a range of alcoholic LiCl solutions in the glassy state. The sharp OH stretching Raman peak due to alcohol molecules weakly hydrogen bonded to chloride ions shifts to lower wavenumbers with an increase in the molecular weight of an alcohol. A simple model calculation suggests that the shift can be mainly ascribed to the change in the mass of an alkyl group of the alcohol rather than a change in the strength of the hydrogen bond.
Raman study of the kinetics of chloride—organic ion exchange across a membrane
Authors: Delimi R. , Maillols J. , Sandeaux R. , Sandeaux J. , Bribes J.‐L. 
Published: May 2005

AbstractThe combination of Raman spectrometry and radiotracer techniques allowed accurate measurements of ion‐exchange kinetics. The exchange of chloride for benzoate or benzenesulphonate ions was studied. These ions were selected as models to simulate the fouling of membranes, a major inconvenience frequently encountered in membrane processes, especially in bio‐industries. The experimental data were compared with the theoretical treatment proposed for two possible hypotheses, namely particle or film diffusion.
Effects of hydrogen bonding and side‐chain conformation on the Raman bands of tryptophan‐2,4,5,6,7‐d5
Authors: Maruyama Teruhiko , Takeuchi Hideo 
Published: May 2005

AbstractTryptophan‐2,4,5,6,7‐d5 (dTrp), in which all the carbon atoms of the indole ring are deuterated, is sometimes used for isotopic labelling of Trp residues in proteins and peptides. The vibrational wavenumbers of the deuterated indole ring were examined in the Raman spectra of eight crystals of dTrp derivatives and compared with the crystal structure and the indole N1‐H stretching wavenumber, a direct indicator of hydrogen bonding strength. The comparison has shown that the Wd4 mode around 1445 cm−1 and the Wd5 mode around 1410 cm−1 of dTrp increase in wavenumber with increase in the strength of hydrogen bonding at the indole N1H site. Another in‐plane vibration of the deuterated indole ring, Wd3, around 1520 cm−1 has been found to change in wavenumber as a function of the absolute value of the torsional angle |χ2, 1| about the Cα—Cβ—C3—C2 linkage. These marker bands of hydrogen bonding and conformation are expected to be useful in the structural analysis of proteins and peptides that are labelled with dTrp.
Electrochemical reduction of CO2 on silver as probed by surface‐enhanced Raman scattering
Authors: Ichinohe Y. , Wadayama T. , Hatta A. 
Published: May 2005

AbstractSurface‐enhanced Raman scattering (SERS) spectroscopy was used to explore the electrochemical reduction of CO2 at a polycrystalline Ag electrode in KHCO3 aqueous solution saturated with CO2 at room temperature. Raman scattering from the oxidation‐reduction cycled Ag electrode suggests the formation of CO and HCOOH by CO2 reduction. At an electrode potential of 0.08 V (vs. Ag/AgCl), adsorbed CO gives rise to a C‐O stretch band at 2128 cm−1. This band decreases in intensity and shifts to higher wavenumber with an increase of negative potential in the range from 0.0 to − 0.24 V. A different potential dependence is observed for the C‐H stretch mode of adsorbed HCOO− (2870 cm−1 at − 0.8 V). The O‐C‐O antisymmetric and symmetric stretch modes of HCOO− observed at near 1550 and 1350 cm−1 decrease in intensity with increasing negative potential, presenting a striking contrast to the C‐H stretch mode. The SERS experiment with a CO2‐saturated KHCO3D2O solution is also described and discussed.
Structural characterization of some quinolin‐8‐ol‐containing azo dyes in solid and solution state as probed by resonance Raman, fourier transform IR and electronic spectroscopic techniques
Authors: Bajpai P. K. , Pal Biswajit , Baul T. S. Basu 
Published: May 2005

AbstractSome 5‐(aryl)azoquinolin‐8‐ol derivatives were studied by resonance Raman, Fourier transform IR and electronic spectroscopic techniques. Analysis of vibrational and electronic spectra was used to determine the azo and hydrazone forms in both the solid and solution states. In the solid state, the compounds remain dominantly in one form and the characteristic bands due to each resonating form were identified. Various structural motifs for protonated, neutral and deprotonated states were proposed based on pH‐dependent studies. The effect of H‐bonding in stabilizing a particular type of structure is also discussed.
Raman spectroscopic study of complex formation between p‐cresol and propionitrile
Authors: Pemberton R. S. , Shurvell H. F. 
Published: May 2005

AbstractRaman spectroscopy, together with factor analysis and band resolution techniques, was used to study complex formation in binary mixtures of p‐cresol and propionitrile in the concentration range 0.025‐0.651 mole fraction of p‐cresol. The envelope of the C  N stretching band of propionitrile in the Raman spectrum between 2300 and 2200 cm−1 was studied. Factor analysis indicated that there were only two linearly independent components in the band envelope. The appearance of a pseudo‐isosbestic point in the area normalized spectra supported this conclusion. For all concentrations, the C  N stretching band envelope was resolved into three components. These were assigned in turn to the free propionitrile, a 1:1 p‐cresol‐propionitrile complex and an overtone or combination mode of propionitrile which does not involve C  N stretching. The equilibrium constant Kc for the formation of the complex was determined at various mole fractions of p‐cresol. The calculated values of Kc exhibited a strong concentration dependence.
Effect of ethanol on SERS spectra of water in a 0.5 M KCl—water—silver electrode system
Authors: Choi Young‐Seok , Kim Jong‐Jean 
Published: May 2005

AbstractThe effect of ethanol on the surface‐enhanced Raman scattering (SERS) of water molecules in a 0.5 M KCI‐water‐silver electrode system was studied by observing changes in the SERS band of water as a function of the time of ethanol addition during the oxidation‐reduction cycle. Hydrogen bond breaking, the main role of ethanol, in the SERS system of water‐ethanol seems to be a necessary condition but not a sufficient condition for observing SERS of water. Surface adatoms of Ag0‐Cl− should also be available at the time of the hydrogen bond breaking by ethanol mixing.
Peculiar intensity distribution in the Raman spectra of copper organoacetylides
Authors: Garbuzova I. A. , Gol'ding I. R. , Schegolikhin A. N. 
Published: May 2005

AbstractRaman spectra of polymeric photoconductive copper organoacetylides (RCCCu)x differ substantially from the spectra of other CuI or AgI compounds which lack photoconductive properties. Also, there is a significant redistribution of band intensities in the Raman spectra of the copper organoacetylides compared with the spectra of the parent acetylenes. The triple bond stretching vibration, v(CC), at ca 1950−1900 cm−1, v(C‐C) at ca 950−700 cm−1 and the lines at ca 600−500 cm−1, caused by deformations of angles between the multiple and single bonds, in the spectra of copper acetylide exhibit an increase in intensity by a factor of 10–100 compared with the spectra of parent acetylenes RCCH. The vibrational bands characteristic of the R substituent itself seem to be very weak in comparison with the unusually strong band of the acetylide in the lower Raman shift range. The origin of these unusual Raman intensities in copper organoacetylides is discussed.
Coherent nuclear motions in light‐harvesting pigments and dye molecules, probed by ultrafast spectroscopy
Authors: Chachisvilis Mirianas , Fidder Henk , Pullerits TÕNu , Sundström Villy 
Published: May 2005

AbstractThe temporal evolution of the transient absorption response of light‐harvesting antennae and dye molecules was studied. Using 40—90 fs pulses coherent nuclear motions were observed in intact membrane‐bound photosynthetic light‐harvesting pigment‐protein complexes, bacteriochlorophyll α monomer and dye molecules in solutions. Computer simulations based on the harmonic Franck—Condon approximation and the Langevin equation describe qualitatively well the wavelength dependence of the oscillations of the mode when exciting and probing in the blue side of the spectrum.
Solvent and frequency dependence of vibrational dephasing on femtosecond time‐scales
Authors: Vöhringer P. , Westervelt R. A. , Yang T.‐S. , Arnett D. C. , Feldstein M. J. , Scherer N. F. 
Published: May 2005

AbstractThe results of degenerate wavenumber third‐order polarization (pump‐probe) measurements of vibrational dephasing and relaxation in a variety of solvents are reported. The 20 fs duration pulses are sufficiently short to allow the preparation and detection of vibrational coherences (i.e. wavepackets) to 800 cm−1 oscillator wavenumber. The high quality of the pump‐probe data permits the unique determination of eight underdamped modes for the cyanine dye under study. The relaxation of the underdamped modes does not show a significant solvent dependence. The relaxation mechanisms that give rise to loss of vibrational coherence and to the solvent‐dependent relaxation of low‐wavenumber (<100 cm−1) modes are discussed. The wavenumber dependence of the vibrational dephasing rate varies with a scaled exponential dependence exp( —ω/ω0), or equally well with the inverse square of the vibrational wavenumber. The exponential form would imply that vibrational dephasing occurs by population relaxation. The latter form, however, may imply higher order coupling between the bath and solute through the solute vibrational anharmonicity such that the off‐diagonal contributions to the prepared wavepacket relax by pure dephasing. Exponentially decaying contributions to the pump—probe signal are found to arise from overdamped modes that are excited by the short laser pulses as opposed to a solvation response. The solvent‐dependent relaxation of these overdamped modes is determined to be similar to diffusive unimolecular barrier crossing dynamics observed in dense media.
Intermolecular vibrational coherence in molecular liquids
Authors: Lotshaw William T. , McMorrow Dale , Thantu Napoleon , Melinger Joseph S. , Kitchenham Robert 
Published: May 2005

AbstractThe femtosecond optical heterodyne detected optical Kerr effect/Raman‐induced Kerr effect (OHD OKE/RIKE) is described in detail with emphasis on the utility for investigating the intermolecular spectra and dynamics of liquids. The femtosecond dynamics of the liquids CS2, benzene and CCI4are addressed through a combination of conventional time‐domain kinetic and Fourier‐transform analyses, and the physical origin of the intermolecular intensity is addressed for each. The distinctions between the excitation mechanisms of the femtosecond OKE/RIKE and other continuous‐wave and picosecond Raman techniques are described. The distinctions between the dephasing mechanisms of intramolecular and intermolecular vibrational modes are discussed.
Scrimshaw: Real or fake? A fourier‐transform Raman diagnostic study
Authors: Edwards H. G. M. , Farwell D. W. , Seddon T. , Tait J. K. F. 
Published: May 2005

AbstractThe Fourier‐transform (FT) Raman spectra of genuine samples of scrimshaw are reported and compared with those of fake scrimshaw, ivory and human milk tooth. The major spectral features in all systems examined were assigned. The application of the FT‐Raman technique to the non‐destructive diagnostic identification of scrimshaw and simulated scrimshaw artefacts is demonstrated.