bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pre‐resonance Raman effect of 1,2,3,4‐thiatriazol‐5‐thiolate and of its molecular complex with sulphur dioxide
Authors: Santos P. S. , Santos J. G. N. 
Published: May 2005

AbstractThe Raman spectra of the 1,2,3,4‐thiatriazol‐5‐thiolate ion and of its molecular complex with sulphur dioxide were obtained. The excitation of the spectra with different exciting radiations shows that in both cases substantial enhancement of several vibrational modes is present. For the ion the enhancement can be assigned to the π → π* transition at ca 320 nm, whereas for its molecular complex the enhancement of the symmetric SO2 stretching clearly indicates that the enhancement must be assigned to the charge‐transfer transition at ca 350 nm. The presence of several enhanced bands in the region of SO2 symmetric stretching is interpreted as being due to SO2 molecules bound to different sites of the ion.
Vibrational study of 4‐nitropyridine N‐oxide. III—The charge‐transfer phenomenon as observed in solution
Authors: Joyeux Marc , Menard Gérard , Dao Nguyen Quy 
Published: May 2005

AbstractThe IR and Raman spectra of various saturated solutions of 4‐nitropyridine N‐oxide (NPO) and NPO‐d4 were recorded in the range 4000–350 cm−1. They were assigned according to previous results for the crystal. A strong Fermi resonance is observed in the νas(NO2) region for solutions of NPO in CCI4, CS2 and C2Br2F4. The hydrogen bonds between a proton of a water or a methanol molecule and the N‐oxide group of NPO are strong. These hydrogen bonds favour one of the two resonance forms of NPO and modify the spectra of the saturated solutions of NPO in donor solvents. Comparison with the vibrational frequencies of the crystal also shows that the main component of the crystalline field is a dipol‐ diple interaction, the strength of which is approximately that of a hydrogen bond between NPO and a methanol or a water molecule.
Raman and infrared spectra, conformational stability and vibrational assignment for 1,1,1,3,3,3‐hexafluoro‐2‐methoxypropane
Authors: Li Y. S. , Larsen R. A. , Cox F. O. , Durig J. R. 
Published: May 2005

AbstractThe Raman spectra of gaseous, liquid and solid 1,1,1,3,3,3‐hexafluoro‐2‐methoxypropane, (CF3)2 CHOCH3, and the corresponding methoxy‐d3 isotope, (CF3)2 CHOCD3, together with the infrared spectra of the gases and solids, have been 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 a single conformer at ambient temperature in the fluid phases with the same conformer present in the solid state. Based on the lack of depolarized Raman lines in the fluid phases, and a predominance of nondescript infrared band contours, it is concluded that the stable conformer is the gauche form which has the methoxy group rotated approximately 60° from eclipsing the secondary carbonhydrogen bond. Thirty‐eight of the 39 normal modes have been assigned based on group frequencies, isotopic shifts, depolarization values and infrared band contours. There appears to be coupling of the CF3 and methoxy torsional modes. Utilizing a coupled‐top barrier calculation, the barrier to internal rotation of the perfluoromethyl groups is estimated to be 2858 ± 100 cm−1 (8.2 ± 0.3 kcal mol−1) based on the torsional frequencies of 107 and 64 cm−1 observed in the solid phase. Several of the fundamentals appear as doublets in the spectra of the solids, which indicates that there are at least two molecules per primitive cell. These results are compared with similar data for some corresponding molecules.
Vibrational spectra of ethylenediammonium metavanadate
Authors: Palopoli C. M. , Etcheverry S. B. , Baran E. J. 
Published: May 2005

AbstractThe infrared and Raman spectra of [NH3CH2CH2NH3](VO3)2 were recorded and are briefly discussed. The vibrational behaviour of this compound resembles that of previously investigated MIVO3 metavanadates, which also possess a closely related chain structure.
Anti‐Stokes low‐frequency Raman spectra of liquids
Authors: Nielsen O. Faurskov 
Published: May 2005

AbstractLow‐frequency Raman spectra of liquids on both Stokes and anti‐Stokes sides were investigated. The spectra are given in the R(v̄) representation. Results for a pure and an impure sample of fluorobenzene were compared. The results allow a distinction between the effects of stray light and fluorescence in the spectra. The same method was used for liquid water at temperatures ranging from the freezing point to 40°C. The background correction for Raman spectra in the R(v̄) representation is discussed. This procedure is of special importance for aqueous solutions of biologically interesting molecules. The use of the anti‐Stokes side is an advantage, as demonstrated by R(v̄) spectra of an aqueous solution of L‐aspartic acid.
Effects of hydrogen bonding on the tyrosine Raman bands in the 1300–1150 cm−1 region
Authors: Takeuchi Hideo , Watanabe Noriko , Satoh Yasuhiro , Harada Issei 
Published: May 2005

AbstractRaman spectra of p‐cresol, a model compound for tyrosine, were measured in solutions of various solvents, paying special attention to the effects of hydrogen bonding on the Raman bands in the 1300–1150 cm−1 region. The frequency of the ν7a (CO stretch) band was found to be sensitive to the state of hydrogen bonding at the phenolic hydroxyl group. It occurs at 1275–1265 cm−1 in proton‐donating states, 1240–1230 cm−1 in proton‐accepting states and around 1255 cm−1 in weakly or non‐hydrogen‐bonding states. This relationship between the ν7a′ frequency and hydrogen bonding was verified in the Raman spectra of L‐tyrosine and its derivatives in the crystalline state. Analysis of the crystal Raman spectra further suggested that the ν7a (CC stretch) frequency also serves as a marker, though less sensitive, of hydrogen bonding and the ν9a (CH bend) frequency reflects the displacement of the OH hydrogen atom from the plane of benzene ring, which may be induced by hydrogen bonding. These Raman bands are strong with UV excitation and are expected to be useful in characterizing tyrosine side‐chains in peptides and proteins by UV resonance Raman spectroscopy.
Multiple adsorbed states and surface enhanced Raman spectra of crotonic and sorbic acids on silver hydrosols
Authors: Kai Sun , Chaozhi Wan , Guangzhi Xu 
Published: May 2005

AbstractSurface enhanced and ordinary Raman spectra of crotonic and sorbic acids were recorded in the range 100‐2000 cm−1. The changes in the SERS spectra of the two compounds on silver hydrosols with time are shown. From the spectra, it is deduced that there are at least three adsorbed states for crotonic and sorbic acids on silver hydrosols. An unusual SERS spectrum is observed when the acid‐sol systems are heated at 100°C for several minutes. Only four new bands apper whereas the other bands which occur in the spectra of the unheated systems disappear. This interesting phenomenon can also be observed for acetic, hydroxyacetic and propionic acids. It is suggested that the unusual spectrum could arise form a particular adsorbed state of the carboxylate ions on silver sols but not the surface‐catalysed reactions.
Raman scattering in ferroelectric [NH(CH3)3]3Sb2Cl9 single crystals
Authors: Miniewicz A. , Jakubas R. , Ecolivet C. , Girard A. 
Published: May 2005

AbstractThe Raman spectra of ferroelectric [NH(CH3)3]3Sb2Cl9 single crystals were studied at temperatures ranging from 90 to 390 K. An assignment of most of the observed bands is proposed. A second‐order phase transition around 364 K leading to a high‐temperature paraelectric phase manifested itself by spliting of the antisymmetric CH3 stretching band (3035 cm−1) below the transition temperature. A temperature dependence study revealed the existence of disorder in the crystal. A systematic measurement of the CH3 torsional vibration Raman band (305 cm−1) was performed and the activation energy (Ea = 2.39 kcal mol−1) of an unidentified organic group HN(CH3)3+ motion was extracted from the half‐width versus temperature curve.
Vibrational analysis of substituted anisoles. I–Vibrational spectra and normal coordinate analysis of some fluoro and chloro compounds
Authors: Lakshmaiah B. , Ramana Rao G. 
Published: May 2005

AbstractThe Raman spectra of 4‐fluoroanisole, 2,3,5,6‐tetrafluoro‐, pentafluoro‐, 2,3,6‐trichloro‐, 2,3,4‐trichloro‐ and 3,5‐dichloro‐anisole were recorded in the region 4000–10 cm−1 and their infrared spectra as mulls were measured in the range 4000–200 cm−1. The Fourier transform far‐infrared spectra of the same samples in the region 600–20 cm−1 were also obtained. A normal coordinate analysis was made for the in‐plane vibrations of these molecules using a 50‐parameter modified valence force field. The force constants were refined using an overlay least‐squares technique. Unambiguous vibrational assignments were made using the potential energy distributions and eigenvectors.
Vibrational and electronic properties of tris(8‐hydroxyquinolinato)vanadium (III)
Authors: Jubert A. H. , Baró A. C. González , Baran E. J. , Sala O. 
Published: May 2005

AbstractA study of the electronic, infrared, Raman and pre‐resonace Raman spectra of the solid complex tris(8‐hydroxyquinolinato)vanadium(III) was performed. The excitation profiles of the vibrational modes that show preresonance on excitation with laser lines within the electronic bands in the visible region are reported and, on this basis and molecular orbital calculations, several vibrational and electronic absorption bands were assigned.
Resonance Raman spectra of molecular selenium and sulphur ions in alkali metal halide crystals
Authors: Fabian H. , Fischer F. 
Published: May 2005

AbstractNew resonance Raman scattering (RRS) sequences of vibrational overtone lines of Se2− SeS−, S3− and Se3− have been observed. By a photochemical technique these centres and S2− can now be produced in alkali metal bromides and chlorides. Vibrational frequencies from RRS or Raman scattering (in the case of S2−) agree with those obtained from luminescence spectra.
Raman spectra and vibrational analysis for benzocaine
Authors: Alcolea Palafox M. 
Published: May 2005

AbstractA detailed study of the NH2 (ND2) modes of benzocaine is reported. The Raman spectra in the solid state and in chloroform solution between 200 and 4000 cm−1 were studied and a tentative assignment is proposed. The torsional barriers of the amine groups were calculated using several methods. The determination of the theoretical torsional frequencies was carried out according to the CNDO/2 method, using a Harmonic approximation and a Hamiltonian calculation.
Effects of pressure on the Raman spectra of a 4:1 methanol–ethanol mixture
Authors: Lemos V. , Camargo F. 
Published: May 2005

AbstractRaman spectra of a 4 : 1 methanol–ethanol mixture were obtained in the pressure range 1 bar‐60 kbar. The evolution of the bands with pressure is discussed qualitatively. Frequency and line‐width pressure coefficients are given.
Remote sampling using a fibre‐optic probe in fourier transform Raman spectroscopy
Authors: Williams K. P. J. 
Published: May 2005

AbstractFourier transform Raman spectroscopy has been carried out remote from the instrumentation using fibre‐optic probes. The quality of the data is good; the measured signal‐to‐noise ratios from spectra obtained using a conventional sampling arrangement are better only by a factor of ca. 5. The choice of fibre‐optic material and grade is crucial to the success of this work. Two different fibres have been tested and compared. Technical improvements are discussed.
Raman scattering investigation of lead mixed halides, PbCl2xBr2(1 − x), as a function of the proportion × ϵ [0, 1]
Authors: Carabatos‐Nédelec C. , Lumbreras M. 
Published: May 2005

AbstractPbCl2xBr2(1 − x) single crystals for various compositions were studied by Raman spectroscopy at 14 K. It is shown that the phonons are of one‐ or two‐mode behaviour when the proportion x varies from 0 to 1. Lattice dynamic and group theory considerations related to structural data allow one to establish a mechanism for the substitutional filling of the anion sites and their participation in the lattice vibrations, the frequency of which has been measured as a function of x at 14 K. The maximum disorder given by the Raman line widths occurs for x = 0.25 and x = 0.75, in accordance with dielectric measurements.
Molecular distortion of distamycin on binding to DNA as revealed by Raman spectroscopy
Authors: Lu Dong Sheng , Nonaka Yasuomi , Tsuboi Masamichi , Nakamoto Kazuo 
Published: May 2005

AbstractThe Raman spectra of distamycin and its complex with DNA were examined in both H2O and D2O solutions. To facilitate band assignments, Raman spectra of several small model compounds of distamycin were also obtained. On binding to DNA, the CO stretching band at 1620 cm−1 (amide I band) of distamycin was shifted upwards by 14 cm−1, whereas a strong pyrrole‐ring stretching band at 1437 cm−1 was shifted downwards by 7 cm−1 in H2O. In addition, most of the Raman bands including amide I, II and III became narrower and sharper on binding to DNA. These results indicate that, in the free state, the dihedral angles around the CC and NC bonds connecting the pyrrole ring and the peptide chain of distamycin fluctuate near 0° (coplanar configruation), whereas in the bound state these angles are fixed and markedly shifted from 0°. Previous x‐ray and NMR studies on distamycin (netropsin)–DNA complexes show that such deviations occur when these drug molecules are bound in the minor groove of DNA. Molecular distortion of distamycin caused by interaction with other polynucleotides has also been elucidated by using such spectral characteristics as diagnosis.
Effective dielectric constants and electromagnetic enhancement on metal island films
Authors: Martín F. , de Saja J. A. , Aroca R. 
Published: May 2005

AbstractAn effective dielectric constant for metal island films has been evaluated using a parametrization of the optical property in terms of the packing factor, the film thickness and a distribution of axial ratios for spheroidal particles. Electron micrographs and plasmon absorption spectra of discontinuous films served as references for parametrical fitting. Enhanced Raman intensities of molecules oriented on the surface of oblate spheroids and a backscattering geometry are discussed.
Vibrational Raman optical activity in forward scattering: Trans‐pinane and β‐pinene
Authors: Barron L. D. , Hecht L. , Gargaro A. R. , Hug W. 
Published: May 2005

AbstractThe first measurements of vibrational Raman optical activity (ROA) have been performed employing a forward scattering geometry. Forward‐scattered ROA spectra of (+)‐trans‐pinane and (−)‐β‐pinene are presented as first examples. Comparison with the corresponding backward‐and right‐angle‐scattered spectra confirmed that the bond polarizability theory of ROA is a good approximation for trans‐pinane, and has identified unequivocally a large isotropic contribution to the ROA in β‐pinene bands at 716 and 765 cm−1 ascribed to interactions between the olefinic methylene twist and a skeletal mode of the pinane structure. Unless large isotropic contributions are present, which is unusual, forward scattering is by far the least favourable of the ROA measurement strategies, which might explain the failure of recent attempts to observe ROA in coherent anti‐Stokes Raman scattering.
Hyper‐Raman spectroscopy
Authors: Ziegler L. D. 
Published: May 2005

AbstractRecent experimental and theoretical developments in spontaneous hyper‐Raman spectroscopy (HRS) are reported. The scope of the general review of HRS presented summarizes the results of this non‐linear scattering technique during the past 10 years. In particular, those aspects of HRS studies which allow novel observations as compared with other spectroscopic techniques are emphasized. HRS investigations of crystals, liquids and surface and electronic resonance enhancement are highlighted.
Symmetric and non‐symmetric hyper‐Raman scattering: Its polarization states and angular dependences
Authors: Kielich Stanisław , Bancewicz Tadeusz 
Published: May 2005

AbstractA theory of three‐photon (hyper‐Raman and hyper‐Rayleigh) scattering is proposed using the approach of irreducible Cartesian and spherical tensors. A general expression for the intensity‐time correlation function of symmetric, non‐symmetric and symmetric‐non‐symmetric three‐photon scattering is derived in terms of separated, irreducible field‐and molecular‐rotational invariants. The occurrence of the various types of scattering is dependent on the physical conditions, i.e. on the molecular symmetry and the ratio of the light frequency and molecular frequency. The (general) number of five irreducible molecular‐rotation and field invariants can undergo a reduction under appropriately chosen experimental and model conditions. The expressions for the intensity function hold for arbitrary (e.g. elliptical) states of light Polarization and angulardistributions. In particular, they are applied to linear and circular polarization. On their basis, equations are derived for the depolarization ratio and reversal coefficient of hyper‐Raman and hyper‐Rayleigh scattering.
Surface‐enhanced hyper‐Raman spectroscopy with a picosecond laser. New vibrational information for non‐centrosymmetric carbocyanine molecules adsorbed on colloidal silver
Authors: Yu Nai‐Teng , Nie Shuming , Lipscomb Leigh Ann 
Published: May 2005

AbstractPicosecond‐excited surface‐enhanced hyper‐Raman scattering (SEHRS) spectra have been obtained for several non‐centrosymmetric oxa‐ and thia‐carbocyanine molecules adsorbed on pre‐aggregated colloidal silver. To facilitate interpretation of the SEHRS results, a comprehensive vibrational study of these dyes by employing Fourier transform (FT) IR spectroscopy, surface‐enhanced Raman scattering (SERS) and the newly developed techniques of near‐IR‐excited FT‐Raman and FTSERS is also reported. The SERS spectra of these carbocyanine dyes are dramatically different from their bulk FT‐Raman and SERS spectra, but exhibit similarities to their FTIR spectra. Many SEHRS lines appear to arise from vibrational modes of the central π‐conjugated chain, in contrast to the appearance of predominantly end‐chromophore vibrations in the Raman spectra. Some of the intense surface hyper‐Raman lines are found to be experimentally undetected or unresolvable by Raman scattering and IR absorption. The results thus conclusively demonstrate that, for non‐centrosymmetric molecules, surface‐enhanced hyper‐Raman scattering is capable of providing important vibrational information that is unobtainable through the Raman and IR methods.
Raman investigation of simple and complex oxides of platinum
Authors: Graham G. W. , Weber W. H. , McBride J. R. , Peters C. R. 
Published: May 2005

AbstractRaman spectra were obtained from PtO, Pt5O6, Pt3O4, α‐PtO2, β‐PtO2, MxNayPt3O4 (M = Co, Ni), PtCoO2 and MPt3O6 (M = Mn, Co, Cd). An enumeration of the allowed Raman modes is made for all of these oxides except Pt5O6, for which the structure is unknown. Polarization measurements allow symmetry species assignments to be made for the lines from α‐PtO2 and PtCoO2, and a likely assignment of the lines from β‐PtO2 is made by analogy with rutile‐structured materials with the rutile structure.
Etude Spectrale de l'Acide Glycolique, des Glycolates et du Processue de Polymérisation
Authors: Cassanas G. , Morssli M. , Fabrègue E. , Bardet L. 
Published: May 2005

AbstractLes spectres Raman et infrarouges de l'acide glycolique, de l'ion glycolate et du glycolate de méthyle ont été analysés de 200 à 4000 cm−1. l'acide glycolique et l'ion glycolate en solution aqueuse se présentent sous forme de monomères hydratés admettant un plan de symétrie, tandis que le glycolate de méthyle possède deux formes d'association, l'une avec une liaison H‐intramoléculaire, l'autre avec une liaison H‐intermoléculaire entre groupements hydroxyles. La déshydratation progressive à température élevée de la solution d'acide glycolique a permis d'identifier les bandes caractéristiques de l'estérification, mettant en évidence le début de la polymérisation.
Resonance Raman spectra of cytochrome a in cytochrome oxidase: Excitation in the 605‐nm absorption region
Authors: Centeno J. A. , Babcock G. T. 
Published: May 2005

AbstractVisible excitation resonance Raman difference spectra, in resonance with the 605‐nm absorption maximum of fully reduced and mixed‐valence cyanide‐bound cytochrome oxidase, were recorded. Under these conditions, the vibrations of ferrocytochrome a are markedly enhanced owing to its dominant contribution to the 605‐nm α‐band absorption of reduced cytochrome oxidase. The effect of H/D exchange in the Raman spectra of cytochrome a was also investigated as a way to establish formyl‐ and vinyl‐peripheral substituent sensitive modes. Measurements of the depolarization ratio dependence of cytochrome a vibrational modes resulted in some isotope‐sensitive modes with characteristic depolarized behavior; however, it was observed that the majority of the visible excitation vibrations exhibit polarized values. This is interpreted as being due to a significant lowering in the molecular symmetry of the heme a porphyrin macrocycle caused by the unusual peripheral substituent pattern of heme a and, presumably, by the strong cytochrome a‐protein interactions. Both structural effects appear to result in a selective enhancement of cytochrome a Eu substituent‐sensitive modes as detected by the low‐frequency resonance Raman spectrum.
Raman microspectrometric study of the dissolution layer of M(NO3)2·nH2O crystals (M = Mg, Ca, Zn and Cd) in their undersaturated aqueous solutions
Authors: Koussinsa Félix , Bertin François 
Published: May 2005

AbstractThe composition of the dissolution layer of certain divalent metal nitrates crystals such as Mg(NO3)2, Ca(NO3)2, Zn(NO3)2 and Cd(NO3)2 in their respective undersaturated solutions was studied by Raman microspectrometry using multi‐channel acquisition of data. A preliminary examination of homogeneous saturated and 20% undersaturated solutions of every solute considered confirmed the existence of individual Raman bands which could be assigned to different solvated species, namely free aquated ions, solvent‐separated ion pairs and contact ion pairs. Some spectral differences were noted between the four cations involved. With Ca2+, Zn2+ and Cd2+ a weak band, assigned to ion aggregates, was also identified. Micro‐Raman spectra of dissolution layers recorded at several steps of the crystal dissolution showed a considerable increase in the proportions of aggregates or contact ion pairs, depending on the type of solute examined. Sharp differences between the dissolution layer composition for Group IA, IIA and IIB metal nitrates were observed.
Theoretical analysis of the resonance Raman spectrum of tryptophan
Authors: Marconi Giancarlo 
Published: May 2005

AbstractThe resonance Raman excitation profiles of tryptophan in the region 240‐200 nm were calculated, taking into account the molecular properties of its chromophore, indole. The relevant quantities such as state displacements and vibronic coupling terms were evaluated by means of quantum mechanical semi‐empirical methods. The results allow the identification of the strongest modes and of the main mechanism governing the Raman scattering. It is found that the spectrum is dominated by the terms in resonance with the Bb and Ba states of indole, with possible interference between these contributions. The vibronic effects, negligible in resonance, become important in preresonance regions.
Vibrational spectra of lactic acid and lactates
Authors: Cassanas G. , Morssli M. , Fabrègue E. , Bardet L. 
Published: May 2005

AbstractThe Raman and IR spectra of lactic acid and sodium lactate in aqueous solution and methyl lactate as a pure liquid were recorded from 3600 to 100 cm−1. Vibrational assignments are proposed for the three compounds. The effects of hydrogen bonding on the ΔOH vibrations of the hydroxyl alcohol group were studied and the results suggest both inter‐ and intra‐molecular hydrogen‐bonded association.