bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Les 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

The 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

Raman 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

Raman 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

The 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

In 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

Raman 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

The 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

Raman 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

Raman 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

The 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

The 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

Raman 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

The 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

A 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.
Raman spectra of bismuth trihalides in the solid and liquid states
Authors: Ichikawa Kazuhiko , Fukushi Kohji
Published: May 2005

Raman spectra were measured for BiBr3 and BiCl3 in the polycrystalline and liquid phases. A new assignment for BiBr3 is proposed on the basis of the temperature dependence of the Raman spectra. An abrupt spectral change originating from an order‐disorder phase transition was observed in BiBr3. In the liquid phase, both compounds showed a very broad composite spectra in the Bi–X stretching vibration region, which can be understood as originating from a mixture of multiply charged bismuth halide complexes in addition to the monatomic halide anions.
Raman spectroscopy of submicron surface layers of crystals and films
Authors: Sushchinsky M. M. , Gorelik V. S.
Published: May 2005

Evidence for surface phonon modes has been found in the Raman spectra of bulk single crystals and in crystalline powders. The Raman spectra of distorted submicron layers and films have been studied as functions of the character of ion implantation and the type of subsequent annealing. The phenomenon of inelastic light hyperreflection from a crystal surface has also been observed.
Raman spectra of agyrodites, M6PS5X (M = Cu and Ag; X = Cl, Br and I), and some related thiophosphates
Authors: Shamir Jacob , Fiechter Sebastian , Wetzel Herbert
Published: May 2005

Raman spectra of copper and silver agyrodites containing different halides were studied. The observed spectra are very similar to those of copper and silver thiophosphates. The spectra were interpreted as resulting from internal modes of the tetrahedral thiophosphate anion, PS43−, indicating that these agyrodites can possibly be formulated as triple salts, M3PS4 · M2S · MX (M = Cu and Ag; X = Cl, Br and I), being basically ionic compounds consisting of monoatomic ions with only polyatomic one covalently bonded PS43− anion.
Trace analysis of tetrasulphonated copper phthalocyanine by surface enhanced Raman spectroscopy
Authors: Aroca Ricardo , Martin Fernando
Published: May 2005

Silver island films are shown to be stable under normal laboratory conditions, and easy to use as optical sensors for the detection of traces of tetrasulphonated copper phthalocyanine. The surface‐enhanced Raman (SER) effect is used in conjunction with a resonance Raman (RR) increase in the analytical signal to levels that allow the detection of nanogram amounts. The relative intensities of characteristic group frequencies do not seem to be altered by the SER enhancement mechanism.
Assignment of iodine BX lines by resonant coherent anti‐stokes Raman spectroscopy
Authors: Dimov S. S. , Pavlov L. I. , Stamenov K. V. , Khadzhiisky N. G.
Published: May 2005

A resonant CARS scheme is described, which allows the examination of the I2 spectrum for discrete and continuum resonances simultaneously. This is the first time such a method of excitation for molecular species has been demonstrated. The absence of P and R branches determined by double resonances with the signal and the pump frequencies makes the assignment easier. It is possible to record all the Raman lines of O, Q and S types, whereas for continuum CARS mainly S lines are detected. The proposed technique makes the spectral structure clearer and the identification simpler. When the temperature of I2 vapour is increased to 330 K, some new Raman lines, the sixth and seventh overtones, are obtained, because of population of higher excited vibrational states. The variation of the anti‐Stokes signal Ia with iodine vapour pressure has also been investigated.
Single‐crystal micro‐Raman studies of ZrS3, TiS3 and several Zr1–xTixS3 compounds (0<x⩽0.33)
Authors: Gard P. , Cruege F. , Sourisseau C. , Gorochov O.
Published: May 2005

Raman and resonance Raman spectra (100–1000 cm−1) of ZrS3, several Zr1–xTixS3 ternary compounds (0<x⩽0.33) and TiS3 single crystals have been obtained using a micro‐Mole Raman instrument. For ZrS3, when using the 514.5 nm exciting line, the αyy and αxx polarizability components give rise to different resonance Raman spectra, demonstrating definitely that two distinct allowed excitonic transitions are contained in the lowest energy absorption band at ca 500.0 nm. In the ternary phase Zr1–xTixS3, the mode behaviour of long‐wavelength optical phonons were investigated through the composition range 0<x⩽0.33: a mixed one‐, two‐ and three‐mode behaviour was observed, depending on the nature of the vibrations; in particular, the three‐mode behaviour of the diatomic v(SS)2− mode can be well accounted for in terms of S22− pairs surrounded by either Zr4+, Ti4+ or Zr4+ and Ti4+ ions and the relative intensities of the three components are in agreement with a statistical distribution of titanium within the ZrS3 type structure. Finally, new polarized Raman spectra of TiS3 have been obtained and band wavenumbers of the Raman active phonons in these compounds compared.
Surface‐enhanced Raman spectroscopy of DNA bases
Authors: Otto C. , van den Tweel T. J. J. , de Mul F. F. M. , Greve J.
Published: May 2005

A Raman microprobe has been used to measure the surface‐enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS spectrum new lines, not visible in the solution spectrum, appear while some lines visible in the solution spectrum are not enhanced to a detectable level and are therefore not seen in SERS. The relative intensities are changed owing to an apparently vibration‐dependent enhancement factor. A line‐broadening effect occurs for most lines except carbonyl stretching vibrations in cytosine and thymine. All SERS spectra show increased contributions of bending vibrations and side‐chain groups. In particular, amino group vibrations in adenine and cytosine are clearly visible. Comparison of the shape and intensity of the carbonyl stretching vibrations in cytosine, thymine and guanine show important differences. It is hypothesized that these differences indicate differences in the orientation of these groups with respect to the surface.
Raman spectra of tetrabromophthalic anhydride and its associated charge‐transfer complex, naphthalene‐tetrabromophthalic anhydride
Authors: Kuok M. H. , Looi E. C. , Tang S. H.
Published: May 2005

The low‐frequency Raman spectra of tetrabromophthalic anhydride (TBPA) and its associated charge‐transfer complex naphthalene‐tetrabromophthalic anhydride (N:TBPA) have been recorded at 300 and 77 K. Nine lattice modes are identified for TBPA, the crystal structure of which is found to be unchanged in the range 300–77 K. On complexation, N:TBPA is observed to have a lowest frequency Raman band at 19 cm−1. Neither of its parent molecules have a Raman band with a lower frequency. The 19 cm−1 mode is assigned to the librational motion of the donor (naphthalene) and acceptor (TBPA) molecules of the complex along their stacking axis.
Raman lattice spectra of the tetrachlorides of germanium, silicon, tin and titanium
Authors: Anderson A. , Basista H. T. , Torrie B. H.
Published: May 2005

Raman spectra of the lattice modes of the Group IV tetrachlorides GeCl4, SiCl4, SnCl4 and TiCl4 at 20 K are reported. Similarities in the spectra suggest that the crystal structures are identical or closely related. Frequency ratios of corresponding peaks and differences in intensity patterns indicate that coupling between modes of translational and librational origin may be an important factor.
Some interference effects in resonance coherent Raman spectroscopy
Authors: Kircheva P. P. , Simeonov S. D.
Published: May 2005

Coherent Raman spectra for resonance pumping conditions and a three‐frequency variant were claculated for polyatomic molecules. A model based on density of states and displaced harmonic oscillators was used. The contributions of different intermediate vibrational levels in the electronic state S1 to the resonance Raman susceptiblity χ and the interference of χ with a non‐resonant electronic background are discussed. It is shown that many intermediate levels belonging to S1 and corresponding to two excited vibrations (the relevant Raman vibration and either one of the others) influence the spectrum significantly, in contrast to the case with absorption. The asymmetry of the Raman line is due mainly to the interference with a non‐resonant background. The method used takes into account the influence of the interference of neighbouring lines on the line shape and also the possible deformation of the lines by the dispersion of the Raman polarizability. The results are in qualitative agreement with known experimental data for some dyes.
Resonance Raman spectrum of the [Cu(HIO6)2]5− anion
Authors: Jubert A. H. , Baran E. J. , Diez A. L. , Sala O.
Published: May 2005

The resonance Raman effect in solid Na5[Cu(HIO6)2].16H2O at room temperature was investigated and the experimental excitation profiles were obtained. From the analysis of the overtone progression of the ν1(A1g) mode, corresponding to the IO symmetric stretching vibration, the X11 anharmonicity constant was determined. The dependence of the Raman intensities on the scattered frequency is briefly discussed.
Solvent dependence of the resonance Raman spectra of azobenzene, 4‐aminoazobenzene, 4‐methylaminobenzene and 4‐dimethylaminoazobenzene
Authors: Barker I. K. , Fawcett V. , Long D. A.
Published: May 2005

Resonance Raman spectra (RRS) of azobenzene, 4‐aminoazobenzene, 4‐methylaminobenzene and 4‐dimethylaminoazobenzene in the solid state and in a range of solvents have been recorded. The RRS of the 4‐aminoazobenzenes are much more solvent dependent than those of azobenzene. Their electronic absorption spectra suggest that their azo‐nitrogens are strongly hydrogen bonded in aqueous media. The RRS were interpreted in terms of intra‐ and inter‐molecular interactions. These molecules probably have a near‐planar geometry in both the solid state and in aqueous media owing to intermolecular interactions. The intramolecular interactions of the nNN orbitals with the π MOs tend to cause ring twisting about the axis of the NN bond. The RRS of the aminoazobenzenes in non‐polar solvents show differences from that of the powder, and these could only be attributed to the formation of non‐planar structures.
Raman spectra of Br2, Cl2 and I2 on various substrates
Authors: Bernussi A. A. , Gualberto G. M.
Published: May 2005

Raman spectra of Br2, Cl2 and I2 adsorbed on graphite, KBr and fused quartz substrates are reported. The results demonstrate that the process of adsorption is strictly related to the type of adsorbate. Different Raman modes were observed for each kind of molecule adsorbed on the substrates. With adsorbed I2, the continuum resonance Raman spectra for the fundamental solid I2 and no frequencies due to adsorption were observed.
Raman spectra of aqueous solutions of formaldehyde and its oligomers
Authors: Möhlmann G. R.
Published: May 2005

The Raman spectra of formaldehyde‐d0 in water‐d0,2 have been recorded. In such solutions formaldehyde is hydrated, thus giving rise to the presence of methylene‐d0 glycol‐d0,2. With increasing concentration, methylene glycol polymerizes yielding soluble and insoluble polyoxymethylene hydrates. By varying the concentration of the solution, the observed Raman transitions could be assigned to vibrations corresponding to the monomer and/or the oligomer hydrates. The Raman spectra obtained for the partly deuteriated molecules permitted improved assignments for the OH bending vibrations and some HCH vibrations.
Surface‐enhanced Raman scattering (SERS) of nucleic acid components in silver sol: Guanine series
Authors: Oh Weon Sik , Kim Myung Soo , Suh Se Won
Published: May 2005

The surface‐enhanced Raman scattering (SERS) of guanine, guanosine, 2′‐deoxyguanosine, 5′‐dGMP, 5′‐rGMP, 5′‐rGDP and 5′‐rGTP adsorbed on aqueous silver sol has been investigated. The peak position and shape of the guanine ring breathing mode are discussed in terms of sugar conformers, the adsorption geometry, the enol‐to‐keto isomerization and the protonation at the N‐7 atom of the guanine base.
Le Système Gazeux Gallium–Chlore: Etude par Spectrométrie Raman. 1–Spectres de Vibration Moléculaire des Espèces Gazeuses: GaCl3, Ga2Cl6, GaCl, Ga2Cl4, Ga2Cl2 et GaCl2
Authors: Hillel R. , Aït‐Hou A. , Berthet M. P. , Bouix J.
Published: May 2005

The molecular vibration frequencies of the gallium–chlorine gaseous species were selected. For the known species Ga2Cl6, GaCl3 and GaCl selection was performed by comparing previous experimental values with our own Raman spectrometric determinations. For the unidentified species Ga2Cl4, Ga2Cl2 and GaCl2 frequency values were evaluated from theoretical literature considerations. The Raman spectra of the vapours obtained by heating condensed gallium and chlorine mixtures are discussed using the selected frequencies and taking into account the Ga2Cl6 and GaCl3 detection limits. With our Raman recording conditions corresponding to well defined spectra, the species are detected up to 5 × 10−3 at. Under these conditions, for Cl/Ga = 3 and between 70 and 500 °C, the main gaseous species are GaCl3 and Ga2Cl6 and the system should be described by the single equilibrium: Ga2Cl6(g)⇌2GaCl3(g). For Cl/Ga = 0.122–3, and between 300 and 800 °C, the representation of the system should be simplified to a single heterogeneous equilibrium between the major species: 2Ga(I)+GaCl3(g)⇌3GaCl(g). In this case, the evolution of the Raman spectra with temperature is explained by taking into account contribution of Ga2Cl4 in very small amounts.
Determination of the secondary structure of proteins from the Raman amide I band: The reference intensity profiles method
Authors: Berjot M. , Marx J. , Alix A. J. P.
Published: May 2005

A simple method for determining the quantitative secondary structure of proteins from their Raman spectra, the reference intensity profiles method, is proposed. This uses as a model the Raman spectral intensities of the backbone amide I vibrations (range 1630–1700 cm−1), corresponding to pure classes of secondary conformations, i.e. α‐helical, β‐sheet and undefined structures. The reference intensity profiles were computed by a step‐by‐step fit of the experimental amide I spectra of a large number of proteins, the secondary structures of which were well known from x‐ray diffraction data in the solid state. The method could be of use in determining the secondary structure of a protein in any state. In the case of a protein in solution, the method solves simultaneously for the secondary structural contents and the subtraction coefficient, thus determining the solvent spectral contribution. The proposed method has been applied with success to a large set of proteins. The correlation coefficient between x‐ray data and the Raman calculated results is close to 0.97 for each class of structure, so accurate estimates of secondary structure may be derived by using the reference intensity profiles method.
Raman spectro‐electrochemistry. II. In situ raman spectroscopic studies of the electrochemical reduction of CO2 at cobalt(II) phthalocyanine‐impregnated PTFE‐bonded carbon gas diffusion electrodes
Authors: Masheder D. , Williams K. P. J.
Published: May 2005

The full resonance Raman spectra of cobalt(II) and cobalt(I) phthalocyanine are presented. By comparison with the Raman spectra of similar compounds, it has been possible to assign many of the bands. The resonance Raman spectrum of cobalt(II) phthalocyanine was replaced by that of cobalt(I) phthalocyanine when a PTFE‐bonded carbon gas diffusion electrode impregnated with a small amount of cobalt(II) phthalocyanine was maintained at a potential of −1.80 V, the gas side of the electrode being exposed to a carbon dioxide atmosphere. These results indicate that cobalt(I) phthalocyanine is a reactive intermediate in the electrochemical reduction of carbon dioxide to carbon monoxide at cobalt(II) phthalocyanine‐impregnated electrodes.
Raman spectra of some MIIV2O6 brannerite‐type metavanadates
Authors: Baran E. J. , Cabello C. I. , Nord A. G.
Published: May 2005

The Raman spectra of polycrystalline samples of the metavanadates MIIV2O6 (with M = Ca, Cd, Cu and Mg), belonging to the brannerite structural type, have been recorded. A general assignment, supported by comparisons with known vibrational properties of other oxovanadium species, is proposed. The compounds only give poorly defined IR spectra, which are not useful for the analysis of the vibrational behaviour.
Some model calculations of the resonance background in coherent Raman spectra
Authors: Kircheva P. P. , Simeonov S. D.
Published: May 2005

Model calculations of coherent Raman spectra under resonance pumping conditions for polyatomic molecules have been carried out. The influence of the resonance background, which originates from the ‘extra’ resonance term of the resonance vibronic transition S0S1, is demonstrated. According to the calculations, the coherent anti‐Stokes Raman scattering (CARS) spectra for ωa = 2ωp−ωs are slightly changed when the resonance background is taken into account. The background contribution to the coherent Stokes Raman scattering (CSRS) for ωs = 2ωp−ωa is higher. It is shown that a line reshaping associated with the concentration changes contains information about the relaxation parameters of the molecules, especially about the dephasing Γ.
Vibrational study of RbD2PO4 single crystals
Authors: Marchon B. , Novak A. , Blinc R.
Published: May 2005

The Raman (4000–10 cm−1) and infrared (4000–32 cm−1) spectra of RbD2PO4 single crystals were investigated at various temperatures. In the low‐temperature phase, the TOLO splitting expected for a P21 polar space group is not observed in the Raman spectra and the vibrational spectra are consistent with a C2h factor group. The II–III phase transition gives rise to a splitting of some skeletal bending modes and the frequency shift of certain vibrations indicates some displacive be haviour, in contrast to the analogous pseudo‐unidimensional crystal of CsD2PO4. Hydrogen bonding in RbD2PO4 is discussed.
Lattice vibrations of phthalic anhydride
Authors: Colombo L. , Kirin D. , Volovšek V. , Long D. A.
Published: May 2005

Low‐frequency polarized Raman spectra of an oriented single‐crystal sample of phthalic anhydride have been recorded and an assignment of observed frequencies has been made on the basis of lattice normal mode calculation performed in the ‘rigid body’ approximation.
Novel cylindrical rotating electrode for anaerobic surface‐enhanced Raman spectroscopy
Authors: Hildebrandt Peter , Macor Kathleen A. , Czernuszewicz Roman S.
Published: May 2005

A simple, small‐volume, anaerobic spectroelectrochemical cell for surface‐enhanced Raman spectroscopy (SERS) has been developed which incorporates a large surface area rotating cylindrical electrode design. The cell has been demonstrated to be effective in minimizing photoreduction of light‐sensitive MnIII protoporphyrin.
Assessment of correction procedures for reduction of Raman spectra
Authors: Brooker M. H. , Nielsen O. Faurskov , Praestgaard E.
Published: May 2005

Recently it has become apparent that for quantitative studies the I(ω) Raman spectrum measured directly from the spectrometer must be corrected for temperature and frequency factors to give a reduced Raman spectrum, R(ω), which is directly proportional to the intrinsic molar scattering factor. Although generally applicable, the R(ω) spectrum finds its greatest application in the low‐frequency region of hydrogen‐bonded and simple molecular liquids and solids. In this paper the general applicability of the R(ω) format is discussed with respect to the low‐frequency spectra observed for simple molecular and more complicated hydrogen‐bonded liquids and solids. Examples are chosen from S8(s), H2O(I), SO2(g) and SO2(I) and CH3CN(I). Further arguments are presented to stress the need to use temperature‐ and frequency‐corrected band shapes for Raman component bands at non‐zero frequency when attempting to deconvolute the Rayleigh band at zero frequency into component sub‐bands.
Analyse Vibrationnelle et Structurale en Série Aliphatique Saturee. VIII—Spectres de Vibration de l'acide Glutarique et de ses Sels Alcalins en Solution Aqueuse
Authors: Delarbre J. L. , Fabregue E. , Maury L. , Bardet L.
Published: May 2005

The Raman and infrared spectra of glutaric acid, (CH2)3[COOH(D)]2, and its potassium salts, CH2)3(COO2KHD and CH23COO2K2, in aqueous solution have been investigated in the range 3500–200 cm−1. The analysis of the polarization ratio of the Raman lines indicated that glutaric acid belongs to point group C1 whereas its ions belong to point group Cs. An assignment of the fundamental vibrations is proposed.
Observation of no significant surface enhancement of Raman scattering from benzoic acid molecules on mercury
Authors: Wang Shou‐Yih , Chou Shen‐Yuan , Liang N. T.
Published: May 2005

There is controversy regarding the surface enhancement of Raman scattering due to liquid Hg, and the enhancement of benzoic acid molecules adsorbed on liquid Hg has been determined to be essentially zero. However, if the noise error bar is taken into account, the maximum enhancement is estimated to be less than 30. The same enhancement was observed when the temperature was reduced in solidifying liquid Hg.
Raman spectra of crystalline antimony triiodide and arsenic triiodide
Authors: Anderson A. , Campbell J. A. , Syme R. W. G.
Published: May 2005

Raman spectra of single crystals of the layered compounds SbI3 and AsI3 at 15K are reported. Polarization measurements allow the eight principal peaks to be classified according to symmetry species. Results of a group theoretical analysis based on both molecular and ionic descriptions of the crystal structure are discussed, and assignments of the observed spectra are proposed. Some ramifications of the more ionic nature of SbI3 on its spectrum are briefly described.
Transform method in resonance Raman scattering with quadratic Franck–Condon and Herzberg–Teller interactions
Authors: Hizhnyakov V. , Tehver I.
Published: May 2005

A new method of considering quadratic vibronic interactions and deviations from the Condon approximation in resonance Raman scattering (RRS) is proposed. The method is used for the generalization of the transform law between absorption and Raman excitation profiles, derived earlier for a basic model. In the case of arbitrary mixing of modes with similar frequencies, a simple generalization of the transform law for first‐order RRS is obtained. For an arbitrary change of frequencies without mode mixing the transform law for the nth‐order RRS is given. The equations are valid for an arbitrary number of modes and also take temperature effects into account.
Halogen‐substituted amides. VII—normal coordinate analysis of 2‐fluoroacetamide and 2‐iodoacetamide
Authors: Murthy E. Krishna , Rao G. Ramana
Published: May 2005

A 30‐parameter modified valence force field has been employed for a normal coordinate analysis of the in‐plane vibrations of 2‐fluoroacetamide and 2‐iodoacetamide. The force constants have been refined using an overlay leastsquares technique. The potential energy distributions and eigen vectors have been used to make unambiguous vibrational assignments.
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

The 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

The 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

The 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

The 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

Low‐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

Raman 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

Surface 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

The 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

The 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

A 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

New 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

A 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

Raman 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.