bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectre de Vibration et Vibrations Normales de I'Acide Pivalique
Authors: Longueville W. , Fontaine H. , Vergoten G. 
Published: May 2005

AbstractL'acide pivalique (TMAA) se présente sous forme de dimères par double liaison hydrogéne. Un calcul en coordonnées normales est mené pour les quatre isotopes d0, d1, d9 et d10. L'affinement conduit à 45 constantes de force et à la description détaillée de l'ensemble des mouvements. Une visualisation est donnée pour certains mouvements caractéristiques (notamment du cycle) et plus particulièrement en basse fréquence (torsions). Les valeurs des barrières de potentiel sont données pour les torsions des groupements méthyl et t‐butyl.
Vibrational assignment of the sn‐1 and sn‐2 chain carbonyl stretching modes of membrane phospholipids
Authors: Levin Ira W. , Mushayakarara Ernest , Bittman Robert 
Published: May 2005

AbstractSince the carbonyl stretching modes of membrane phospholipids reflect molecular perturbations and reorganizations at the bilayer interface region, a definitive assignment is desired of the vibrations associated with the carbonyl transitions at either the sn‐1 or sn‐2 lipid chain position. Ether glycerol phospholipids containing one alkyl ether chain and one acyl chain, with the carbonyl group in either the sn‐1 or sn‐2 chain, provide lipid systems for establishing these assignments. rac‐1‐0‐Hexadecyl‐2‐palmitoyl‐sn ‐glycero‐3‐phosphorylcholine yields a carbonyl stretching mode at 1716 cm−1, while the carbonyl mode for 1‐palmitoyl‐2‐0‐hexadecyl‐sn ‐glycero‐3‐phosphorylcholine shifts to 1737 cm−1, By eliminating the gauche bond at the α‐carbon position of the sn‐2 acyl chain in 1‐0‐hexadecyl‐2‐acetoyl‐sn‐glycero‐3‐phosphorylcholine, the lower frequency carbonyl fundamental reverts to a higher frequency (1739 cm−1) characteristic of a nearly trans conformation about the C2C1 bond in the ester linkage.
Low frequency vibrational study and reorientational motions in M(CO)3(η6C6H6) M = Cr, Mo, W
Authors: Chhor K. , Lucazeau G. 
Published: May 2005

AbstractRaman and infrared spectra (5‐2000 cm−1) of Cr(CO)3(η6‐C6H6), Mo(CO)3 (η6‐C6H6) and W (CO)3 (η6‐C6H6) and of the deuterated derivatives (d6) of the Cr and Mo complexes have been recorded in the 5‐300 K temperature range. The low frequency region has been extensively studled. New modes are identified and a new assignment in this region is proposed. The temperature dependence of the low frequency spectra is discussed in connection with recent quasielastic neutron scattering results. Broadenings of the Raman bands are interpreted in terms of anharmonicity and vibrational dephasing connected with large amplitude motions associated with a potential barrier of 4.7 kcal mol−1, A qualitatlve representation of the potential driving the torsional motion is proposed and it is pointed out that the intermolecular potential plays a dominant role. 2π/6 ring jumps involving an activation energy of 3.9 kcal mol−1, as deduced from neutron scattering in Cr(CO)3(η6‐C6H6), occur, but the proportion of molecules in the state of jump is only 0.3% at 300 K and therefore the rate of dynamic disorder is too low to induce an order‐disorder phase transition. This result is consistent with our calorimetric measurements.
Precision Raman investigation of the ν1 mode of vibration of SO, WO and MoO in aqueous solutions of different concentrations
Authors: Dean K. J. , Wilkinson G. R. 
Published: May 2005

AbstractThe ν1 vibrational Raman modes of the anions SO, WO and MoO have been studied in aqueous solution with great precision, and the effect of different alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) carefully recorded as a function of concentration. The results show that the symmetric vibrational frequency of the anions is dependent on both the concentration and on the cation present in the solution. Precise values of the anion ν1 frequencies were found at infinite dilution by extrapolation. These frequencies are: 980.75±0.1 cm−1 for SO, 931.1±0.1 cm−1 for WO and 986.1±0.1 cm−1 for MoO. When the alkali metal cations Li+ or Na+ were present in the solution, the anion ν1 frequency was shifted to a higher value than the infinite dilution frequency, whereas, when K+, Rb+ or Cs+ were present in the solution, the anion ν1 frequency was decreased. The frequency shifts were also found to depend linearly on the square root of the solution concentration. The results also indicate that in ionic aqueous solutions the water molecule behaves as though it has a radius of 1.15±0.01 Å and a polarizability of 0.39±0.01 Å3. An empirical relation between cation volume and polarizability has also been demonstrated.
Raman intensity and conjugation: 6—a Raman study of non‐planarity in substituted styrenes, biphenyls and stilbenes
Authors: Schmid E. D. , Topsom R. D. 
Published: May 2005

AbstractA study of the Raman intensities of ν8 mode of benzene in series of styrene, biphenyl and stilbene hydrocarbons is reported. It is shown that, after correction for the resonance Raman effect, the intensities can be related to the degree of planarity of the molecules via a previously derived relationship between the intensity and the length of the conjugated system.
The hyper Raman spectra of some chloro‐ and bromo‐methanes and some group IV tetrachlorides
Authors: Dines T. J. , French M. J. , Hall R. J. B. , Long D. A. 
Published: May 2005

AbstractThe hyper Rayleigh and hyper Raman spectra of the following Group IV halides are reported: the liquids CCl4, CHCl3, CH2Cl2, CHBr3, CH2Br2, CH3Br, SiCl4, GeCl4 and SnCl4 and CBr4 in solution in CCl4. Relative hyper Rayleigh and hyper Raman intensities and depolarization ratios have been measured. These are discussed and the intensities compared with those observed in Raman and infrared spectra.
Normal‐coordinate analysis of retinal isomers and assignments of Raman and infrared bands
Authors: Saito Shigeki , Tasumi Mitsuo 
Published: May 2005

AbstractNormal‐coordinate calculations have been performed for the all‐trans, 9‐cis, 11‐cis and 13‐cis isomers of retinal using a model structure in which the β‐ionone ring was replaced with a simplified structure. Most of the Raman and infrared bands observed from these isomers in the solid state are assigned on the basis of the results of calculation. The vibrational characteristics of each isomer are discussed.
Raman spectra and vibrational dephasing of methylacetylene
Authors: Kalasinsky V. F. , Little T. S. 
Published: May 2005

AbstractThe Raman spectra of gaseous and liquid methylacetylene have been recorded. The spectrum of the gas provides new data for verifying the vibrational assignments of certain A1 and E fundamentals. Some of the vibrations exhibit hot bands whose origins have been determined on the basis of their Raman intensities. The isotropic scattering for the three fundamentals in the liquid state was studied as a function of temperature. The hot band structure in the liquid state was modeled by using curve‐fitting procedures and the assignments made for the gas phase. The isotropic bandwidths for the fundamentals were observed to increase with decreasing temperature, and the broadening is consistent with the existence of a weak hydrogen bond in pure methylacetylene.
Pulsed laser induced vibrational resonance Raman scattering of chlorophyll a dimers
Authors: de Wilton A. , Haley L. V. , Koningstein J. A. 
Published: May 2005

AbstractThe pulsed laser induced Raman spectrum of dry chlorophyll a (Chl a) in hexane is reported. This sample is excited with a wavelength which is in resonance with an absorption band of the Chl a dimer at 432 nm. The observed resonance Raman excitation profile for several Raman bands shows that two electronic origins of the dimer are located at 434.1 and 435.4 nm and these are assigned to a pair of pseudo exciton levels. Features of this excitation profile are used to discuss the observed Raman spectra.
Raman and infrared spectra of spermidine and spermine and their hydrochlorides and phosphates as a basis for the study of the interactions between polyamines and nucleic acids
Authors: Bertoluzza A. , Fagnano C. , Finelli P. , Morelli M. A. , Simoni R. , Tosi R. 
Published: May 2005

AbstractThe Raman and infrared spectra of the polyamines spermidine and spermine and of their corresponding hydrochlorides and phosphates have been studied. These systems can be regarded as models of the molecular interactions between polyamines and nucleic acids, and the observed spectra are discussed in relation to this. Medium strong and strong NHCl and NHO hydrogen bonds are present in both the polyamine hydrochlorides and phosphates and the proton is predominantly located on the nitrogen atom. In the case of the phosphates, the Raman spectra indicate the formation of HPO groups, which can also interact among themselves by strong OHO hydrogen bonds.
Single crystal Raman spectra of magnesium and zinc perchlorate hexahydrates
Authors: Patel M. B. , Agarwal Anshu , Bist H. D. 
Published: May 2005

AbstractRaman spectra of Mg(ClO4)2·6H2O and Zn(ClO4)2·6H2O single crystals have been recorded in the region 4000–20 cm−1 using an Ar+ laser as a source of excitation. The polarization behaviour of the Raman lines under different crystal orientations is reported. It is shown that the water molecules lie almost in a plane perpendicular to the crystal c‐axis.
Contribution à l'Etude par spectroscopie de vibration des interactions amine‐eau dans le monohydrate de l'Isobutylamine
Authors: Favier R. , Et J. Potier B. Bonnet 
Published: May 2005

AbstractLes interactions isobutylamine‐eau ont été étudiées par spectroscopie de vibration infrarouge et Raman. L'étude préliminaire de l'isobutylamine pure montre l'existence, dans l'état liquide, de deux isomères de rotation, un seul conformère étant favorisé par cristallisation. Dans l'état solide les fréquences de vibrations sont caractéristiques de l'existence de liaisons hydrogène due à un enchaǐnement (RNH2)x dans lequel l'environnement de l'atome d'azote est tétraèdrique. L'analyse des spectres infrarouge et Raman du complexe équimoléculaire isobutylamine‐eau montre la formation de chaǐnes dans lesquelles la molécule d'eau casse la liaison NH…︁N pour former une liaison NH…︁O. Les fréquences de vibration sont en accord avec un environment tétraèrdique de l'atome d'oxygène analogue à celui observé pour l'atome d'oxygène dans le glace II. Les spectres de l'homologue deutérié sont beaucoup plus complexes du fait de l'apparition d'un échange hydrogène‐deutérium entre le group NH2 et la molécule D2O.
Studies of the electronic Raman spectra of atomic chlorine excited by an argon ion laser
Authors: Chang Hua , Lin Hong Ming , Hwang Mei Hua 
Published: May 2005

AbstractThe electronic Raman transition hetween 2P3/2 and 2P1/2, states has been found at 882.5 cm−1 for atomic chlorine. The intensity of this peak increased quadratically with increasing laser power. Therefore, the process involved one, and only one, photon in producing Cl. A model of photodissociation and photopredissociation is suggested, which could explain the dependence of the relative intensity on the laser frequency as well as the laser power. This model also predicts the population ratio of Cl in the two atomic states; the experimental results agreed with the predicted values.
Raman spectra of the arabinonucleosides ARA‐A and ARA‐C Compared with the spectra of adenosine and cytidine
Authors: Theophanides T. , Hanessian S. , Manfait M. , Berjot M. 
Published: May 2005

AbstractRaman spectra of the arabinonucleosides ARA‐A and ARA‐C and their protonated species have been recorded and compared with those of adenosine and cytidine and protonated adenosine and cytidine. The vibrational modes of the molecules have been studied and the characteristic frequencies have been assigned. The cis‐trans geometry of the sugar hydroxyl groups is clearly indicated from the Raman spectra of the solids and aqueous solutions. The lattice modes of these species are observed in the low‐frequency region of the spectra below 200 cm−1 and they, too, reflect the different puckering of the cis‐trans sugar hydroxy grops in the crystals.
Resonance Raman spectra of radical cations of bridged diquaternary salts of 2,2′‐bipyridine
Authors: Barker David J. , Cooney Ralph P. , Summers Lindsay A. 
Published: May 2005

AbstractRaman spectra are reported for several bridged diquaternary salts of 2,2′‐bipyridine. Resonance Raman spectra and some excitation profiles of the coloured radical monocations obtained from the diquaternary salts by one‐electron reduction are also reported. Selected frequencies of the parent dications are correlated with changes in the torsional angle between the aromatic rings of the bipyridinium moiety. These correlations, when applied to the spectra of the radical monocations, suggest that the radicals exhibit reduced torsional angle and increased inter‐ring bond order, compared with the parent dications. These changes are consistent with predictions of increased inter‐ring π‐electron delocalization, associated with radical formation. The torsional angle appears to decrease for the radical monocations with increasing number of bridging methylene groups. This is opposite to the trend known to occur in the parent dications.
Raman spectroscopic studies of aqueous tetramethylammonium silicate solutions
Authors: Dutta P. K. , Shieh D. C. 
Published: May 2005

AbstractThe influence of cations on aluminosilicate zeolite formation is well recognized. This Raman study showed that on a molecular level, there is a significant difference in the type of silicate species that are solubilized by tetramethylammonium hydroxide and sodium hydroxide at certain hydroxide ion concentrations. A cubic, cage‐like silicate species is formed in 1.0–1.4 M tetramethylammonium hydroxide, whereas no such species was formed in alkali metal hydroxide at any concentration. Band assignments for the cubic species [(CH3)4N]8Si8O20 are made from the Raman and infrared spectroscopic data. Elucidation of such structural effects by Raman spectroscopy can help explain the unique influence of the cation on zeolite formation.
Δ M = 3 Spin‐flip acceptor scattering and zerofield splittings
Authors: Scott J. F. , Handschy M. A. 
Published: May 2005

AbstractIn the presence of an external magnetic field, shallow acceptor levels in II‐VI semiconductors split into a J =3/2 quartet of nearly evenly spaced levels. At cryogenic temperatures only the MJ = −3/2 state is thermally occupied, and two transitions are expected: ΔM = 1 (−3/2 to −1/2) with αxx and αxy polarizabilities (z is the direction of applied field) and ΔM =2 (−3/2 to +1/2) with αxz and αyz polarizabilities. In addition to those transitions we have observed at high magnetic fields (H⩽4T) a third transition with αxx and αxy polarizability; we assign it as ΔM = 3 and show that although it is strictly forbidden in zero field, its cross‐section varies theoretically as H2, and experimentally it becomes comparable in intensity to the ΔM = 2 transition in both ZnTe: Li and ZnTe: Ag at 10 T. This analysis allows a more accurate evaluation of the gyromagnetic ratio g = − 2k =0.567 ± 0.025 and of the crystal field parameter q̃ in the spin Hamiltonian of Zn Te: Li as q̃ = −0.012±0.006; the sign and magnitude of q̃ have previously been in doubt and can be different for different acceptors. Non‐zero spin‐flip energies are found, interpreted as due to strain or exchange. These appear to vary with acceptor concentration, and are E1/2 = 1.45± 0.29 cm−1 and E3/2 =4.39±0.14 cm−1 for 0.01% Li. The fact that E3/2 ≈︁ 3E1/2 indicates that the mean field approximation is valid, with an effective field in zero external magnetic field of He ≈︁ 3.5 T.
Spectroscopic studies of explosives II–Detection of nitro compounds on Silica gel and glass with a Raman microprobe
Authors: Carver F. W. S. , Wyndham D. P. , Sioclair T. J. 
Published: May 2005

AbstractRaman microprobe spectra were obtained from tetramethoxymethane tetranitrate, 1,3,5‐trinitro‐1,3,5‐triazacyc‐lohexane and 2,4,6‐trinitro‐l‐methylbenzene adsorbed on silica gel and supported on glass. The nitro compounds were detected at levels down to 1 μg on silica gel and 100 pg on glass and gave identifiable spectra. The results were compared with those obtained in earlier macro‐sampling work.
Light scattering in LiH crystals with LO phonon emission
Authors: Plekhanov V. G. , Altukhov V. I. 
Published: May 2005

AbstractThe results of an experimental and theoretical study of the resonant secondary emission spectra at 4.2 K of wide gap ionic insulators (lattice of the NaCl type) are presented. The well developed character of the free exciton luminescence and the multiphonon resonant Raman scattering spectra (which contain mainly LO lines) point to Frölich intraband scattering of free excitons (polaritons) on LO phonons. It is established that the ratio of the scattered line intensities of the first and second order has a square dependence on the scattered polariton wave vector. For the spectral range 4.97–3.30 eV the dispersion of the scattering cross‐section with participation of LO(Γ) phonous has been measured for the first time. A resonant enhancement of the multiphonon scattering line intensities on the LO(Γ), LO(X) and TO(Γ) phonons has been observed. Calculation of the dispersion of the scattering cross‐section has been performed using a theoretical model taking into account the scattering of hydrogen‐like excitons on LO phonons. Analysis of the cross‐section leads to the conclusion that in the excitation frequency range ω > Eg‐4R the main contribution to σ(ω) comes from the discrete excitonic states, but for ω Eg‐4R the states of the electron‐hole continuum play the main role. Agreement between theory and experiment has been achieved by taking into account the electronic damping. The influence of the excitation intensity on the structure of resonant Raman scattering spectra in LiH crystals is also discussed.
Study of the phase transition of CsD2PO4 by Raman scattering
Authors: Aoki Magane , Kasahara Masaru , Tatsuzaki Itaru 
Published: May 2005

AbstractRaman scattering from CsD2PO4 was observed in the paraelectric and ferroelectric phases. The line width and the frequency of one of the totally symmetric A modes were measured as a function of temperature. An anomalous change in the line width was observed and this is qualitatively discussed in relation to the frequency shift below the transition temperature.
A Raman spectroscopic discrimination between the sub‐gel phase and the GIII Gel phase of aqueous dipalmitoylphosphatidylcholine bilayers
Authors: Wong P. T. T. , Mushayakarara E. , Mantsch H. H. 
Published: May 2005

AbstractRaman spectra of aqueous dipalmitoylphosphatidylcholine (DPPC) bilayers have been measured as a function of temperature for samples incubated at 2 °C and for non‐incubated samples. The nature of the transition from the GII gel phase of the hydrated lipid into the sub‐gel phase on incubation is entirely different from that of the transition from the GII gel phase into the GIII gel phase of the non‐incubated lipid. The GIII gel phase has a monoclinic interchain packing, whereas the sub‐gel phase exhibits a triclinic interchain structure. In the sub‐gel phase the acyl chains are rigid and more ordered even than those in solid DPPC.
The influence of molecular interactions on the invariants of the Raman scattering tensors. IV—the tensors of ring vibrations of pyridine in the presence of electron acceptor reagents
Authors: Mierzecki Roman 
Published: May 2005

AbstractThe effect of various electron acceptor molecules on the intensities of the ν1 ν12 Raman bands of pyridine has been studied quantitatively; the changes in the Raman tensor invariants have been evaluated and are discussed.
On the electric field dependence of Raman scattering
Authors: Aussenegg Franz R. , Lippitsch Max E. 
Published: May 2005

AbstractThe influence of high electrostatic fields on Raman scattering has been studied. For fields approaching 108 V m−1 in polymers a contribution to the Raman intensity due to the non‐linearity of the Raman polarizability could be demonstrated. These results are in agreement with theoretical considerations. The band position does not change within the achieved resolution of 0.1 cm−1 for fields up to 1.7 × 108 V m−1, as also expected from theoretical estimates. With pulsed fields of duration < 1 μs, field strengths exceeding the static breakdown strength could be applied. In this case, however, a very complex pre‐breakdown behaviour was observed, influencing the Raman scattering in a manner not yet understood.
Resonance Raman scattering from the metastable electronic state of an Na2[Fe(CN)5NO]·2H2O single crystal
Authors: Krasser W. , Woike Th. , Haussühl S. , Kuhl J. , Breitschwerdt A. 
Published: May 2005

AbstractRaman spectroscopy was used to characterize the extremely long duration metastable state of Na2[Fe(CN)5NO]·2H2O single crystals. By excitation with light of λ>540 nm only the Raman spectrum of the ground‐state configuration is obtained. With an excitation wavelength in the range 540–450 nm, the vibrational bands of the ground‐ and metastable‐state configurations are observed together with approximately equal intensities. In the wavenumber shift range 400–2200 cm−1 for each vibrational mode of the ground state a Raman band is found, but no splitting of degenerate modes appears. It is concluded that the symmetry of the molecule is not changed by pumping the metastable state. Excitation with light of λ=406.7 nm proves the existence of higher energetic states of the metastable configuration, which do not combine with the ground state. In addition to a thermal decay channel, there exists a further channel for depopulation of the metastable state using red light. Absorption spectroscopic measurements show the existence of an excited electronic state at 685 nm in the metastable configuration. This low‐lying energy level crosses with the first excited electronic level of the ground‐state configuration.
Resonance Raman cross‐section and polarization of light scattered from trans‐polyacetylene
Authors: Kuzmany H. , Knoll P. 
Published: May 2005

AbstractThe resonance excitation profile for the CC stretch mode of trans‐polyacetylene has been measured between 1.55 and 3 eV. For the main vibrational line at 1460 cm−1 a resonance enhancement of two orders of magnitude was observed for excitation with 1.7 eV. The peak position of the resonance shifted to higher values for a Raman shift larger than 1460 cm−1. The relationship between this position and the Raman shift was found to be different from that between the excitation energy and the satellite peak position. Experimental results have been compared with calculations from the particle in the box model for interrupted conjugations. Semiquantitative agreement was obtained for the various Raman shifts. The difference between the behaviour of the resonance peak and the satellite peak is shown to result from the influence of the distribution function and the lineshape function. The depolarization ratio for the CC stretch mode was observed to be 0.6, which is larger than expected for a randomly oriented anisotropic scatterer. However, it is in agreement with a situation where the scatterer is randomly oriented within one plane.
Theory of coherent anti‐stokes continuum resonance Raman scattering in diatomic molecules
Authors: Beckmann A. , Baierl P. , Kiefer W. 
Published: May 2005

AbstractA theory is presented which describes coherent anti‐Stokes resonance Raman scattering via continuum electronic states of diatomic molecules. It is applied to the dissociative continuum of the bounded B(3Π0+u) state and the continuum of the repulsive 1Π1u state of the iodine molecule. The theory allows numerical calculations of continuum resonance CARS spectra.