bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman spectra of caesium and rubidium tetrachloroaluminates in the solid state
Authors: Rubbens A. , Wallart F. , Barbier P. , Mairesse G. , Wignacourt J. P. 
Published: May 2005

AbstractRaman spectra of both polycrystalline samples and single crystals of CsAlCl4 and RbAlCl4 (space group Pnma (D)) have been recorded in the temperature range 298–80 K.As for the other chloroaluminates, we find the four characteristic bands of the tetrahedral AlCl anion at 353, 128, 485–503, 180–187 cm−1 and 356, 127, 486–505 and 180–187 cm−1, respectively, for the salts CsAlCl4 and RbAlCl4. The Raman spectra of single crystals of these two compounds are similar and show that these two salts are isostructural. An assignment of the observed bands is proposed. The results are compared with those for the polyatomic cation (nitrosyl and ammonium) tetrachloroaluminates.
Normal and resonance Raman spectra of gaseous chlorine excited with an argon ion laser
Authors: Chang Hua , Hwang Dah‐Min 
Published: May 2005

AbstractNormal and resonance Raman effects in gaseous chlorine were carefully studied with a powerful argon ion laser. No resonance Raman behaviour could be detected in the spectra excited by visible laser lines with wavelengths down to 4545Å. The fine structures of the normal Raman spectra were examined. Resonance Raman spectra were obtained with the 3638 and 3511 Å UV line excitation. Progressions with seven overtones were recorded. The fine structures in each overtone region were analysed and assigned as the Q and S band heads of various isotopic molecules. The Raman cross‐section was enhanced only by a factor of 1.3 in the resonance case and the integrated intensity of each overtone was about one‐third of that of the fundamental. Those two characteristics indicate that the resonance Raman term in gaseous chlorine is small in comparison with the normal Raman term even when the energy of the excitation laser line is 7593 cm−1 above the dissociation limit.
Spectroscopy study of [Ni(NH3)6]X2 compounds. III reorientational correlation times of NH3 and ClO4 groups in [Ni(NH3)6](ClO4)2
Authors: Janik B. , Janik J. M. , Janik J. A. 
Published: May 2005

AbstractBy applying the Raman band profile analysis method, reorientational correlation times of NH3 groups and (ClO4)− ions in [Ni(NH3)6] (ClO4)2, have been obtained. These times are of the order of psec at room temperature. They increase with decreasing temperature. NH3 reorientations do not show any significant changes when the temperature passes the phase transition region (173 K–143 K). (ClO4)− reorientations, on the other hand stop abruptly at the phase transition in 173 K. A comparison with IR and neutron scattering results leads to a choice of 120° angular jumps as the NH3 reorientational model.
Molecular reorientations and intermolecular interactions: Raman spectra of the three crystalline phases of p‐dichlorobenzene
Authors: Crafts D. L. , Bellows James C. , Prasad Paras N. 
Published: May 2005

AbstractThe three crystalline phases of p‐dichlorobenzene (DCB) are related to each other primarily by molecular reorientations. In order to examine the anisotropy in the crystal interactions, the effect of these molecular reorientations on the phonon dispersion and the internal vibrational exciton splitting is investigated with Raman spectroscopy. Isotopically mixed crystals (DCB‐h4:DCB‐d4) are used to measure the phonon dispersions and the vibrational exciton splittings. The results obtained show that these dynamic properties are highly sensitive to molecular reorientation, revealing an anisotropy in the crystal interactions. The anisotropy in the crystal interaction is also found to be mode selective.
Non‐enzymatic hydrolysis of acetylcholine studied by Raman spectrometry
Authors: Lautié Alain , Aslanian Dimitrina , Balkanski Minko , Merlin Jean‐Claude , Dupaix Alain 
Published: May 2005

AbstractRaman spectrometry complemented by infrared spectrometry have been used to study the modifications of the acetylcholine (Ach) molecule during the course of its non‐enzymatic hydrolysis in the pH range 6 to 12. The evolution with time of Ach Raman spectra, in the 600–1800 cm−1 frequency range, has been related to the course of the reaction and the final products have been identified. The rate constant has been determined using the relative intensities of vibrations associated with the Ach molecule and with the products of the reaction. The calculated value was in agreement with the value obtained by the pH‐stat method.
Etude des systèmes SiAs‐halogènes et GeAs‐halogènes par spectrométrie Raman de gaz à haute température
Authors: Bouix Jean , Hillel Roger , Michaelides Adonis 
Published: May 2005

AbstractRaman spectroscopy, because it is the most convenient method of determining the components of gaseous mixtures in equilibrium at high temperature, is well fitted for a systematic study of crystal growth mechanisms of inorganic solids by chemical transport.We have shown that the reaction between chlorine, bromine, or iodine and solid silicon or germanium arsenide is irreversible and complete between 150 and 400 °C, resulting in the formation of arsenic and the appropriate tetrahalide of silicon or germanium. At higher temperatures the tetrahalide vapour reacts with the arsenide in excess forming arsenic and the appropriate dihalide. This equilibrium reaction effects the chemical transport. The dihalides show resonance Raman scattering involving either the symmetric stretching or bending vibration.
Raman spectroscopy with intensified vidicon detectors: A study of intact bovine lens proteins
Authors: Mathies Richard , Yu Nai‐Teng 
Published: May 2005

AbstractRaman spectra of intact ocular lenses contain important structural information related to aging and cataract formation. However, the direct application of Raman spectroscopy to human eyes for cataract diagnosis has been considered unsafe because of the high laser power (∼100 mW) required to generate Raman spectra using the photomultiplier‐photon counting (PMT‐PC) detection method. The clinical application of Raman spectroscopy has become more likely with the development of sensitive multichannel optical detectors such as the ‘silicon intensified target’ (SIT) coupled to an optical multichannel analyzer (OMA). We have incorporated the SIT in a novel mismatched subtractive dispersion double monochromator that has optimum stray light (<5×10−9), throughput, and resolution for these experiments. It is demonstrated that the new SIT–OMA detection method is capable of obtaining high‐quality Raman spectra of an intact bovine lens with a laser power (∼1 mW) significantly below the threshold for retinal damage. The multichannel and photon counting detection systems have been carefully compared under high and low light level conditions so that the advantages of the SIT‐OMA system for other Raman experiments may be easily evaluated.
Resonance Raman spectra of iron(II) 2,2′‐bipyridyl complexes
Authors: Miller Philip J. , Chao Robert Shih‐Liang 
Published: May 2005

AbstractThe resonance Raman effect is reported for the bipyridyl ligand vibrations in the complexes {Fe(bipy)3}+2, {Fe(bipy)2(CN)2} and {Fe(bipy)(CN)4}−2. The Raman spectra were obtained using exciting laser line frequencies coincident with the visible metal–ligand charge transfer absorption bands. The identity of the resonantly enhanced Raman bands is correlated with the nature of the absorption bands. The resonantly enhanced excitation profiles of the bipyridyl vibrations are analyzed in terms of the theory of resonance Raman scattering. The results indicate that the high frequency components of these bands are primarily due to a superposition of the vibrational progressions of the symmetric ligand stretching modes and not due to additional charge transfer absorptions.
Implications of modelling the chromophore of rhodopsin and bacteriorhodopsin with resonance Raman spectra of retinal Schiff bases
Authors: Marcus Michael A. , Lemley Ann T. , Lewis Aaron 
Published: May 2005

AbstractResonance Raman spectra of protonated and unprotonated Schiff bases of all‐trans retinal with propylamine, hexylamine, butylamine, deuterated butylamine (d9), methylamine and N15 methylamine have been obtained. The spectra of methylated and deuterated butylamine Schiff bases of retinal have also been recorded. It was found that the carbon–nitrogen stretching vibration associated with the Schiff base is insensitive to changes in the mass and/or length of the saturated hydrocarbon group attached to the Schiff base except for the case of methylamine. The fingerprint region, on the other hand, is sensitive to alterations in the Schiff base substituent. Deuterating the Schiff base has a larger effect on the carbon–nitrogen stretching frequency than replacing the Schiff base nitrogen N14 with N15. Furthermore, the data on deuterated Schiff bases indicate that the CCH bending vibrational mode is altered by deuteration. Implications concerning use of these compounds for modelling visual pigments and bacteriorhodopsin are discussed.
Raman spectroscopic study of thortveitite structure silicates
Authors: Bretheau‐Raynal F. , Dalbiez J. P. , Drifford M. , Blanzat B. 
Published: May 2005

AbstractSingle crystals of ytterbium, lutetium and scandium pyrosilicates were grown by a floating zone technique associated with an are image furnace. The recorded infrared and Raman spectra allow complete attribution of internal and external modes, in good agreement with group theory predictions.
Laser Raman spectra of some group IB metal carbonyl cations
Authors: Neppel Anton , Hickey James P. , Butler Ian S. 
Published: May 2005

AbstractThe Raman spectra of [Ag(CO)2]+ and [Cu(CO)4]+ in fluorosulphonic acid at—50°C have been investigated in the CO stretching region. These data, together with previously reported infrared results, favour D∞h symmetry for the Ag(I) species and Td symmetry for the Cu(I) species. These structures are in accord with those predicted for the complexes using the valence shell electron pair repulsion (VSEPR) theory.
Resonance Raman spectra of bromine: Scattering cross‐sections for simultaneous resonance with two excited states, B3∏ (0+) and 1∏(1)
Authors: Coxon J. A. , Gramari N. , Jacon M. 
Published: May 2005

AbstractThis paper is concerned with the quantitative interpretation of the resonance Raman excitation profile (REP) of bromine. This is the first example of a diatomic molecule where two excited electronic states, B3∏ and 1∏, strongly intervene in the Raman tensor. The numerical calculations of all the Franck–Condon factors and densities for both excited electronic states using RKR methods are presented. The results are then applied to the calculation of the REP. This rigorous calculation is compared with an approximate method, the reflection approximation. The main properties of the REP, in particular the presence of a strong maximum on the red wing of the absorption band, are accounted for by the present theory and the contributions of the two excited electronic states are discussed.
A Raman spectroscopic study of single crystals of NaH2PO4 · 2H2O and NaD2PO4 · 2D2O
Authors: Toupry‐Krauzman N. , Poulet H. , Le Postollec M. 
Published: May 2005

AbstractPolarized Raman spectra of single crystals of NaH2PO4·2H2O and NaD2PO4·2D2O have been measured as a function of temperature in the wavenumber shift range 10–3600 cm−1. Changes of phonon frequencies due to directional dispersion are found. All the observed bands have been assigned using group theory. The Raman spectra are fully consistent with the presence of strong acidic hydrogen bonds and the existence of a weakly bound water molecule.
Matrix isolation Raman spectroscopy at high pressures
Authors: Jodl H. J. , Holzapfel W. B. 
Published: May 2005

AbstractA special pressure cell for Raman spectroscopy is described which contains a sample chamber with special scattering geometry and a ruby manometer for in situ pressure measurements. Typical results are given for the fundamental vibrational Raman spectra of matrix‐isolated nitrogen molecules.
Uracil and thymine monoanions in solution: Differentiation of tautomers by laser Raman spectroscopy
Authors: Lippert Bernhard 
Published: May 2005

AbstractLaser Raman spectroscopy permits an identification of the N‐1 and N‐3 deprotonated tautomers of uracil and thymine and a qualitative estimation of their distribution in solution. The applicability of the method with respect to the differentiation of other heterocyclic tautomers is briefly discussed.
A practical analysis for coherent anti‐stokes Raman scattering (CARS) spectra
Authors: Fleming James W. , Johnson Charles S. 
Published: May 2005

AbstractIn coherent anti‐Stokes Raman scattering (CARS) spectra for condensed phases, the shape and position of an isolated line depend on the Raman cross‐section, the linewidth, the vibrational frequency and the nonresonant electronic susceptibility. Equations are presented here which relate these quantities to the measured maximum and minimum intesities and the associated frequency shifts, ωL — ωs. In the case of electronic resonance enhancement, where the Raman amplitude has real and imaginary parts, a complete analysis was obtained using the intensity Imid measured at the mid‐frequency between the extrema as the fifth known quantity. However, when the electronic susceptibility is also complex, it is a completely general result that its real and imaginary parts are mixed with those for the Raman amplitude so that only certain combinations of quantities can be obtained. Equations are also presented to correct for the interference resulting from neighboring lines. The derivations are based on perturbation theory expressions for the third‐order nonlinear susceptibility χ(3), and the results are interpreted in terms of susceptibility plots in the complex plane.
The Raman spectrum of ammonium meta‐periodate
Authors: Shurvell H. F. , Brown R. J. C. , Korppi‐Tommola J. 
Published: May 2005

AbstractRaman spectra of NH4IO4 and ND4IO4 have been recorded at several temperatures between 83 K and 371 K. As the temperature is increased, several bands due to both internal and external modes of the periodate ion are shifted to lower wavenumbers. There is a crossing of the Ag and Eg librational modes of the IO4−ion near 200 K. The bands due to the ammonium ion vibrations are broadened as the temperature is increased and the librational lattice mode is no longer observable above about 200 K. The present results are correlated with observations from NQR, NMR and X‐ray diffraction studies.
Vibrational spectra and conformations of epifluorohydrin
Authors: Kalasinsky V. F. , Wurrey C. J. 
Published: May 2005

AbstractThe infrared and Raman spectra of solid, liquid and gaseous epifluorohydrin have been recorded. For the fluid phases, there are a number of spectral triplets which can be interpreted as arising from a cis and two nonequivalent gauche conformations. The number of bands which disappear as the solid sample is annealed indicates that a single conformation exists in the crystalline state. The temperature dependence of the intensities of Raman lines for the liquid state is consistent with enthalpy differences of approximately 0.6 and 0.4 kcal mol−1 between the most stable and each of the less stable conformers. The existence and identities of the less stable conformers are discussed.
Vibrational dephasing of the SiH stretching mode in liquid trichlorosilane
Authors: Baglin Frank Geile , Dehart Dillard L. 
Published: May 2005

AbstractThe Raman signal from the v1 mode of trichlorosilane has been examined by dilution in several solvents. Temperature studies were also conducted and include data from the disordered solid phase of the neat sample. The results of these studies show that (a) the v1 fundamental is involved in a dephasing process process controlled by the intramolecular potential function; (b) the neat liquid has a longer dephasing time than in any of the solvents, indicating memory retention as an intermolecular process. Additionally, environmental effects (broadening) are pronounced and appear to be related to the dipole moment of the solvent. The theoretical model proposed by Rothschild1 is used to strengthen the interpretive case offered for the dephasing mechanistic process of the fundamental.
Raman spectrum of single crystals of monoclinic B‐type gadolinium sesquioxide
Authors: Zarembowitch J. , Gouteron J. , Lejus† A. M. 
Published: May 2005

AbstractThe Raman spectrum of a single crystal of monoclinic B‐type (C) gadolinium sesquioxide is presented. The low temperature polarization studies allowed the unambiguous attribution of 20 among the 21 normal modes expected according to the C2h factor group analysis predictions.
The origin of intense Raman spectra from pyridine at silver electrode surfaces: The role of surface carbon
Authors: Howard Martin W. , Cooney Ralph P. , McQuillan A. James 
Published: May 2005

AbstractIntense Raman spectra from pyridine at polished silver electrode surfaces, subjected to a single anodic cycle, appear to be associated with pyridine adsorption in graphitic carbon overlayers on the silver surface. This interpretation is based on the absence of pyridine line enhancement for ‘clean’ (or carbon‐free) systems and the simultaneous appearance of intense pyridine and carbon spectra for the systems subjected to a single anodic cycle. Features arising from surface carbon are evident in spectra reported by earlier authors. The evidence for the presence of carbon is based firstly on the conversion of the species in question to hydrocarbons at reducing potentials and secondly on similarities in the spectra of the systems: Ag/0.1 M KCl, Ag/0.1 M KF and Ag/0.1 M KCl, pyridine, in the region of the D and G modes of graphite (1200–1700 cm−1). Similar intensity–potential curves for the pyridine line at 1008 cm−1 and the carbon band at 1595 cm−1 indicate a surface association between these two species. The stability of the pyridine species generating the 1008 cm−1 line on a dry electrode surface favours intercalation (internal adsorption) rather than external physical electrosorption on carbon. The line at 1025 cm−1 is assigned to a silver(I) pyridine complex.
Raman spectra and crystal structure of polycrystalline tetramethylammonium salts
Authors: Kabisch G. 
Published: May 2005

AbstractThe Raman spectra of eight polycrystalline Me4N+ salts have been measured and are discussed in relation to crystal structures. In most of the salts, several degenerate bands of the cation show splittings due to site symmetries lower than Td. From the spectral shapes in the methyl deformation and stretching region and the intensity ratio of the two NC4 skeletal deformation modes, the extent of cation distortion in each particular salt can be deduced. These distortions are strongest in the halides, whereas no significant crystal field effects are found in the SnCl62− and CdCl3− salts. Anion Raman bands and frequencies of lattice modes are also reported.
The vibration‐rotation Raman spectra of 18O2, 17O18O, 17O2 and 16O2
Authors: Edwards H. G. M. , Long D. A. , Najm K. A. B. , Thomsen M. 
Published: May 2005

AbstractThe vibration‐rotation Raman spectra of the oxygen species 18O2, 17O18O, 17O2 and 16O2 have been recorded and analysed; the spectra of the 17O18O and 17O2 species are reported for the first time. The B0 and α values from these analyses were used to calculate values for the equilibrium‐state rotational constants, Be, and hence the bond lengths, re. The following values were obtained:
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Linear wave‐vector dependence of zone center optical phonons
Authors: Bizek Hana M. , Imaino W. , Ramdas A. K. , Rodriguez S. 
Published: May 2005

AbstractSymmetry arguments including time reversal show that the polar, degenerate optical zone center phonons exhibit a dispersion linear in wave‐vector provided the crystal does not possess improper symmetry operations. After reviewing the theory, we present experimental results on the Raman spectra of α‐quartz and bismuth germanium oxide which illustrate this effect.
The electron impact spectra of SO2
Authors: Vušković L. , Trajmar S. 
Published: May 2005

AbstractThe methods of electron impact spectroscopy were applied to gain information about the triplet states of the SO2 molecule. The present studies indicate hitherto undetected triplet excitations at around 4.9, 7.8, 9.3 and 10.5 eV. The angular distribution of the scattered electrons is consistent with a ã 1B1 assignment at 3.4 eV and also shows that triplet excitation(s) is present in the 4.4 eV (Ã 1B1) region. The high‐energy, low‐angle spectrum yielded relative optical absorption coefficients which, when normalized to the optical data at 200 nm, agree well with previous optical measurements in the 320 to 96 nm range. In the present work the absorption coefficients were extended down to 50 nm.
The vibrational spectra of ethylene monomer and dimer in argon matrices
Authors: Cowieson D. R. , Barnes A. J. , Orville‐Thomas W. J. 
Published: May 2005

AbstractRaman spectra of ethylene trapped in argon matrices are compared with the corresponding infrared data. Bands due to monomer and dimer species could be distinguished by their concentration dependence. Possible structures of the dimer are discussed.
Multiphoton absorption in direct gap solids
Authors: Mitra S. S. , Vaidyanathan A. 
Published: May 2005

AbstractThe two photon absorption coefficient for several alkali halides and zincblende type semiconductors has been calculated by models developed by Keldysh, Braunstein and Basov. It is shown that the Keldysh formula is closely related to Braunstein's for allowed‐allowed transitions, while Basov's formula correspond to Braunstein's formula for allowed‐forbidden transitions. A number of inprovements and corrections are pointed out. However, comparison with published experimental data show that even the best calculated values are at least an order of magnitude smaller. A more realistic model that combines the elements of second order perturbation theory and band structure calculations gives excellent agreement with experimental data on several direct gap semiconductors. The three photon absorption coefficient is treated by a third order perturbation method and compared to the results obtained by the Keldysh model.
Resonance and pre‐resonance Raman spectra of the antitumor drugs adriamycin and daunomycin
Authors: Manfait Michel , Bernard Luclen , Theophanides Theophile 
Published: May 2005

AbstractResonance and pre‐resonance Raman spectra of solids, aqueous and D2O solutions of adriamycin and daunomycin are reported. The Raman bands are due to the chromophore anthraquinone and are coupled with the first electronic π‐π* transition of the molecules. All the observed Raman bands have been assigned to vibrations of the chromophore. Resonance enhancement for most of the Raman bands has been observed in relation to the π‐π* transition. Spectra taken at different pH values show interesting Raman intensity changes owing to a shift of the π‐π* transition towards longer wavelengths. An π‐π* transition has been assigned to the shoulder near 500 nm of the absorption spectra of the molecules on the basis of the intensity changes of some Raman bands involving the carbonyl vibrations.