bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Raman scattering from molecular‐dye films on silver
Authors: Aroca Ricardo , Loutfy Rafik O.
Published: May 2005

Surface enhanced Raman scattering has been observed for phthalocyanine films deposited on silver. Surface roughness or 'metal islands' seems to be crucial for large enhancement factors. Metal enhanced Raman spectra appear to show specific changes in the relative intensities of vibrations associated with the inner part of the macrocycle.
Analyse Vibrationnelle et Structurale en Série Aliphatique Saturée 4—Spectres de Vibration de I'Acide Diméthylmalonique et de ses Sels Alcalins en Solution Aqueuse
Authors: Delarbre J. L. , Maury L. , Bardet L.
Published: May 2005

Les spectres de vibration (Raman et infrarouge) de l'acide dimétyhlmalonique et de ses sels alcalins en solution aqueuse (H2O et D2O) ont été anregistrés de 250 à 4000 cm−1. L' ananlyse de l'état de polaristion des raies Raman observées permet de conclure que l'acide diméthylmalonique et le sel neutre appartiennent au groupe C2 tandis que le sel acide répond au groupoe Cs, le plan de symétrie étant bissectrur du groupe COO−. Une attribution des raies observées aux vibrations fondamentales est proposée.
The resonance Raman spectrum of the 18O‐enriched MnO ion
Authors: Jubert A. H. , Varetti E. L.
Published: May 2005

The resonance Raman spectrum of the MnO ion enriched in 18O and dispersed in a RbBr matrix was obtained. The symmetric stretching fundamental band and its first three overtones were measured for the five possible isotopomers, allowing an estimation of the corresponding harmonic frequencies and anharmonicity constants. An explanation for the observed trend in these constants is proposed.
The Raman spectra of BH and BD isolated in alkali halides at 80 K
Authors: Memon M. I. , Sherman W. F. , Wilkinson G. R.
Published: May 2005

Raman spectra of BH and BD ions isolated in alkali halides are presented. Effects produced by changing the supporting lattice and by 10B to 11B and H to D isotopic substitution are discussed. The need for a careful analysis of the Fermi resonance that is an important feature of these spectra is explained.
An investigation of the lattice and interlayer water vibrational spectral regions of muscovite and vermiculite using Raman microscopy. A Raman microscopic study of layer silicates
Authors: Haley L. V. , Wylie I. W. , Koningstein J. A.
Published: May 2005

The micro Raman spectrum of ∼100fg of the clay materials Muscovite and Vermiculite in the region of 600 cm−1 −3300 cm−1 is reported. An attempt has been made to assign the observed Raman shifts in particular those of H‐bonded OH−, which may have significance to an understanding of the role which clay plays in the absorption of soil water.
The vibrational spectra and normal co‐ordinate analysis of NaOX (X = H or D)
Authors: Kanesaka Isao , Tsuchida Masaaki , Kawai Kiyoyasu
Published: May 2005

The vibrational spectra of NaOX (X = H or D) at room temperature and 77 K are reported. A normal co‐ordinate analysis has been carried out to assign the observed bands on the basis of the valence force field. The force constants were adjusted by considering a bond distance and reproduce well the observed frequencies. In the dispersion relations on k2 and kx the librational modes were found to be insensitive to k, whereas the translational modes except for the A1g and B1u modes vary considerably with k. Some bands were assigned to the combination band between a fundamental and an acoustic mode.
Temperature dependence of Raman active modes in triethylenediamine
Authors: Sauvajol J. L.
Published: May 2005

The temperature dependence of Raman active modes in monocrystalline Triethylenediamine has been studied by Raman spectroscopy. The linewidths and frequencies of these modes have been measured in the temperature range 110‐330 K (that is the low temperature phase for which T < Tc = 351 K). A strong broadening is observed at higher temperatures in this range for the A2 and E1g librons. This can be related to the activation of disorder in the low temperature phase.
On the nature of the lowest excited states of styrene: Calculation of the resonance Raman spectrum and pre‐resonance profiles
Authors: Marconi G.
Published: May 2005

The nature of the low‐lying excited single states of styrene has been investigated through calculation of the resonance Raman spectrum and pre‐resonance Raman profiles of the three modes of CC stretching nature. A reasonable agreement with experiment is found and an analysis of the main contributions to the intensity is provided in terms of vibronic matrix elements. The possibility of destructive interference of diagonal and off‐diagonal terms is analysed for the three modes examined.
Plasmon‐phonon coupling effects in picosecond Raman scattering of nonequilibrium semiconductor plasma
Authors: Vasconcellos A. R. , Luzzi R.
Published: May 2005

The ultra‐fast time‐resolved Raman spectra of a highly photoexcited semiconductor plasma is calculated. Information is provided on the time‐evolution of irreversible relaxation processes that develop in the system. It is described how plasmon‐phonon interference effects in the Raman spectra are affected in the far‐from‐equillbrium state of the system. We used a theoretical method, based on a generalization of Gibbs algorithm to nonequilibrium situations, and a numerical analysis appropriate for the case of GaAs samples is presented.
Magnetic electronic Raman optical activity of osmium (IV) hexabromide, iridium (IV) hexachloride and uranocene
Authors: Barron L. D. , Vrbancich J.
Published: May 2005

Magnetic optical activity is reported in electronic resonance Raman transitions of OsBr, IrCl and U(C8H8)2 in solution. All the effects are observed in the form of couplets which originate in separate Raman transitions between magnetic components of the initial and final levels. These can give detailed information about the magnetic structure of the ground and low‐lying electronic states, particularly the sign of the g‐factor and the ordering of magnetic sub‐states in general. For example, effects in the 466 cm−1 electronic Raman band of U(C8H8)2 confirm that the MJ = ±4 level lies below the MJ = ±3 level. We also use the magnetic Raman optical activity to identify a very weak U(C8H8)2 Raman band at 675 cm−1 with a vibrational‐electronic combination transition.
Absence of surface enhanced Raman scattering (SERS) by pyridine on cleaned roughened silver electrodes
Authors: Mernagh Terrence P. , Cooney Ralph P.
Published: May 2005

Anodically roughened silver electrode surfaces which have been cathodically cleaned exhibit virtually no pyridine surface spectrum i.e. no surface enhanced Raman scattering (SERS) effect. Scanning electron microscopy (SEM) reveals no detectable change in the surface roughness features as a result of the cathodic surface cleaning. The absence of SERS has been confirmed for cathodically‐cleaned flat (unanodized), roughened (anodized) and massively roughened (repetitively anodized) silver surfaces. These findings appear to rule out flat‐surface or roughened‐surface (metal‐particle) enhancement of the pyridine spectrum itself. Other evidence confirms that the intensely scattering SERS phase is [carbon‐pyridine] and not pyridine itself. The carbon and pyridine SERS intensities are shown to coincide on the potential scale and to exhibit a stoichiometric interdependence. These results rule out coadsorption and argue strongly in favour of internal trapping rather than external adsorption of pyridine on carbon. The insensitivity of pyridine SERS to the presence of a radical scavenger confirms the absence of radical ion resonance enhancement. These results are consistent with parallel Auger studies which reveal that localized laser damage (producing a zone of pure carbon in the case of pyridine) is probably the primary factor in SERS from silver electrodes. The implications of these and other results for a reduced silver‐generated enhancement factor are considered.
Comments on the use of BOXCARS for gas‐phase CARS spectroscopy
Authors: Greenhalgh Douglas A.
Published: May 2005

Calculations of integrated intensity and 90% interaction length have been performed for planar and folded BOXCARS phase matching schemes for gas‐phase Coherent Anti‐Stokes Raman Scattering (CARS). These results show that, in general, for a half crossing angle of the pump laser beams of less than 20 degrees there is no difference between folded and planar BOXCARS. Further, the calculations indicate that the optimum Stokes beam diameter is 2/3 of the pump beam diameter; this result is also true for colinear CARS. The calculations also show that the interaction length can be accurately estimated from a simple geometric formula. The adaptation of planar and folded BOXCARS for ‘single‐ended’ operation (input and signal beams transmitted through the same observation window) is outlined and discussed.
Spectroscopy at very high pressures: 45—structural phase transitions in A2HgI4, (A = Ag, Cu, Tl, 1/2Pb), investigated by Raman scattering
Authors: Adams David M. , Hatton Peter D.
Published: May 2005

Raman spectra and phonon pressure dependencies are reported for the spinel‐related iodides A2HgI4, (A = Ag, Cu, Tl and 1/2Pb) at high pressures in a diamond anvil cell. In each case the upper pressure limit of observation was set by changes in band gap which caused darkening and photodecomposition. New phase transitions were found for Cu2HgI4 (8 and 25 kbar), Tl2HgI4 (11.5 kbar) and PbHgI4 (7 and 14 kbar). Transitions in Ag2HgI4 were located at 3.3, 5.9 and 8.1 kbar, confirming and extending earlier evidence. The β‐Ag2HgI4 to phase II transition at 3.3 kbar appears to be second‐order in type. Using Landau's theory, Ag2HgI4 II was shown to adopt space group C. Similarly, at the I/II transition in Cu2HgI4, the new phase (II) can have either D or C symmetry.
A Raman spectroscopic study of the structural phase transition and reorientational motions of the ClO ions in KClO4
Authors: Toupry N. , Poulet H. , Le Postollec M. , Pick R. M. , Yvinec M.
Published: May 2005

Polarized Raman spectra of oriented single crystals of KClO4 performed over a large temperature range (300–800 K) have been used to investigate the mechanism of the 583 K phase transition. It is shown that the transition can be described using an order parameter and a mechanism based on the reorientation of the ClO ions is proposed. A Raman study of the plastic phase (above 583 K), using the shape of the bands associated with the internal modes, leads to a measure of the orientational density probability and the orientational self‐correlation functions of the perchlorate ions.
Analyse Vibrationnelle des Acides Cyclobutanedicarboxyliques‐1,3 cis et trans en Solution Aqueuse: 2—L'Acide Cyclobutanedicarboxylique‐1,3 trans et le Cyclobutanedicarboxylate Dipotassique
Authors: Fabrègue Eliane , Cassanas Geneviève , Bardet Lucette , Escale Roger , Chapat Jean‐Pierre
Published: May 2005

Une étude par RMN a montré que l'acide cyclobutanedicarboxylique‐1,3 trans a en solution aqueuse une conformation gauche axiale‐équatoriale. L'analyse des spectres de polarisation Raman prouve que ee composé n'a aucune symétrie, tandis que le dianion cyclobutanedicarboxylate appartient au groupe de symétric Cs, les plans des deux groupements carboxylates étant orthogonaux. Une attribution des fréquences des vibrations fondamentales est proposée pour chaque composé.
Raman spectra of alkali halide/NCO− systems
Authors: Mohammad M. R. , Sherman W. F.
Published: May 2005

The Raman spectra of twelve different alkali halide/NCO− systems have been investigated, and these spectra have been compared with the previously‐studied infrared spectra. In the external mode region there are significant differences in the infrared and Raman spectra associated with the in‐band features.
Raman and infrared spectra of calcium and barium sulphamates
Authors: Muthusubramanian P. , Sundara Raj A.
Published: May 2005

Raman spectra of a single crystal of calcium sulphamate and polycrystalline barium sulphamate have been recorded at room temperature. Infrared spectra of polycrystalline calcium and barium sulphamates for the region 20‐4000 cm−1 are also presented. The assignments made are supported by potential energy distribution calculations. The data show that there is no water of hydration in barium sulphamate. The N‐S torsional mode is observed in both the compounds. This has not been found in other sulphamates of this family. The results indicate very weak hydrogen bonding in these crystals.
The polarized Raman spectra of CsCdCl3 single crystals
Authors: Kuok M. H.
Published: May 2005

Raman scattering measurements on CsCdCl3 single crystals have been made at 15 K. First‐ and second‐order phonon scattering are observed and the symmetry species of the first‐order spectrum have been partly determined by means of polarization studies.
Raman spectral studies of bleomycin A2 and related structural fragments: A probe for bleomycin–DNA interactions
Authors: Freedman Teresa B. , Santillo Frank S. , Zimba Carl G. , Nafie Laurence A. , Dabrowiak James C.
Published: May 2005

Raman spectra have been obtained for bleomycin A2 and selected fragments. Virtually all of the features in the bleomycin Raman spectrum can be attributed to the preresonance enhanced vibrational transitions of the 2,4′‐bithiazole moiety as determined by comparison to the Raman spectra of bithiazole fragments. The Raman spectrum of bleomycin is dominated by a very intense band at 1542 cm−1 that can be approximately assigned as a bithiazole ring stretching mode. This feature may serve as a probe of bithiazole environment in bleomysin ‐DNA interactions.
Hyper‐Raman spectra and frequency dependence of soft mode damping in SrTiO3
Authors: Denisov V. N. , Mavrin B. N. , Podobedov V. B. , Scott J. F.
Published: May 2005

The hyper‐Raman spectra of SrTiO3 were studied in the range 85–710 K. The temperature dependance of frequencies and damping of all the vibrations, including the soft F1u and silent F2u modes, was obtained. Using the hyper‐Raman spectra and a Green's function analysis, we calculated the damping function Γs(ω, T) in the frequency region 20–200 cm−1 for temperatures between 300 and 710 K. It was shown that the behavior of the soft mode damping may be described by invoking soft mode decay into two acoustic phonons (ωs→ωac+ωac) plus an additional channel via annihilation of one acoustic phonon (ωs+ωac→ω176). The temperature dependence of the phonon resonance between the soft mode and the nearest polar optical phonon (at 176 cm−1) was studied. Quantitative analysis of this phonon resonance was carried out to obtain parameters characterizing both modes: signs and relative magnitude of the hyper‐Raman matrix elements; the soft mode damping; and the resonance coupling constant, which yields interference effects.
Carbonyl stretching vibrations of uracil studied by 18O isotopic substitutions with UV resonance Raman spectroscopy
Authors: Chinsky L. , Hubert‐Habart M. , Laigle A. , Turpin P. Y.
Published: May 2005

Resonance Raman spectra of uracil and its 18O isotopically substituted species (in positions 2‐, 4‐ and 2,4‐) have been obtained in neutral aqueous solutions with 257 nm excitation. A computer decomposition of the 1560‐1740 cm−1 region showed the presence of five bands in this region, at 1629, 1659, 1673, 1689 and 1706 cm−1 in the case of uracil. The shifts and intensity variations caused by isotopic substitution are also reported, and these help precise assignments of these bands. The discussion also takes into account the resonance Raman spectra of 2‐ and 4‐thiouracil and 2,4‐dithiouracil, obtained with 300 nm excitation.
Influence of Faraday rotation on the selection rule of phonon Raman scattering in magnetic materials
Authors: Peng‐Xiang Zhang , An Tu
Published: May 2005

We report the first examination of the influence of Faraday rotation on the selection rule of phonon Raman scattering in magnetic materials. It is shown that the original selection rule for phonons will no longer be valid owing to the introduction of Faraday rotation. By applying a transverse ( is the direction of light propagation) or a longitudinal () magnetic field, the effect of Faraday rotation can be switched off or on. The changes of the intensity and mode structure of phonon scattering in the two configurations are related directly to the absorption and the magneto‐optical figure of merit, Q ( = θF/2α, where θF is the specific Faraday rotation and α is the coefficient of absorption). The result also shows that introducing Faraday rotation offers a new chance of identifying some vibration modes which are otherwise impossible. Taking garnet (O) as example, the relationship between phonon scattering intensities and Faraday rotation and absorption was calculated for typical scattering configurations. The results can be checked experimentally using magnetic materials with suitable Q values.
Cure profiles of light‐cured dental composites by Raman spectroscopy
Authors: Louden J. D. , Roberts T. A.
Published: May 2005

A Raman spectroscopic method for the measurement of cure profiles of light‐cured dental composites is presented.
Surface‐enhanced Raman spectra of aromatic amino acids and proteins adsorbed by silver hydrosols
Authors: Nabiev Igor R. , Savchenko Vladimir A. , Efremov Evgeniy S.
Published: May 2005

Surface‐enhanced Raman spectra of some amino acids (Phe, Tyr, Trp, His, Leu and Ala) and cytotoxin I from Naja naja oxiana adsorbed by silver hydrosols have been obtained. The spectra are enhanced from 100 to 200 times. Addition of aqueous solutions of the amino acids to the hydrosol resulted in the appearance of an absorption band in the visible spectral range (450–650 nm) due to formation of the hydrosol‐amino acid complex. The surface‐enhanced Raman spectrum and the absorption band disappear after short ultrasonic treatment of the complex. Comparison of electron microphotographs of the silver hydrosol and the hydrosolprotein complex clearly demonstrate coagulation of the silver micelles, apparently caused by protein adsorption and complex formation. The excitation profile of the Phe‐Ag hydrosol complex was obtained and this agreed well with the position of the longwave absorption band. From the analysis of the intensity ratios of the Stokes and anti‐Stokes components of the Raman spectra of Phe in the silver hydrosol and in aqueous solution the mechanism of the resonance Raman effect is strongly supported. The problem of possible conformational changes of the adsorbed molecules was considered. From CD spectra of cytotoxin I in aqueous solution and those in the silver hydrosol it was concluded that the backbone conformation of the protein did not change, but the environment of the aromatic residues altered. Experiments on the binding of an equimolar mixture of Phe and Ala with silver hydrosols showed that competitive binding took place, and thus the aromatic amino acid is mainly responsible for the surface‐enhanced Raman effect.
Resonance Raman spectra of iron(II) and ruthenium(II) complexes with perdeuteriated 2,2′‐bipyridine
Authors: Strekas Thomas C. , Mandal Santosh K.
Published: May 2005

Resonance enhanced Raman spectra are reported for the complexes M(bpy‐d8)32+[MFe(II), Ru(II)] and Ru(bpy‐d8)2Cl2, where bpy‐d8 is perdeuteriated 2,2′‐bipyridine. Correlations are made with the corresponding resonance enhanced modes of the hydrogen containing compounds for the spectra obtained in resonance with the visible metal to ligand charge‐transfer (MLCT) absorption bands. In particular, the effect of in‐plane CH(D) deformation modes on the resonance active vibrations is discussed.
Unit cell group analysis of orthorhombic crystals: Detailed investigation of the effect of arbitrary choice of axes
Authors: Rulmont A.
Published: May 2005

The results of the group theoretical analysis of the normal vibrations of crystals having orthorhombic space groups can depend on the arbitrary choice of axes because there is no unambiguous way to define a unique axis. This situation creates some confusion in the results published by different authors. We have investigated in detail the problem of the unit cell group analysis of the orthorhombic structures D2h and D2 and the results are presented in two tables for practical applications. It is shown that it is possible to express the irreducible representations as a function of experimental parameters, which gives a clearer view of the physical situation than the conventional notation (Ag etc.).
Vibrational spectra of tribromoacetonitrile and [15N] tribromoacetonitrile
Authors: Arenas J. F. , Marcos J. I. , Suero M. I.
Published: May 2005

The IR and the low‐frequency Raman spectra of liquid tribromoacetonitrile and its 15N isotopic derivative were recorded and assigned on the basis of isotopic shifts and depolarization ratios. The isotopic product rule has been successfully applied by assuming a CNDO optimized geometry.
The Raman Spectrum of Cd3As2
Authors: Jandl S. , Desgreniers S. , Carlone C. , Aubin M. J.
Published: May 2005

The first Raman data for Cd3As2 are reported, showing nine peaks at room temperature with a strong fluorescent background.
The resonance Raman spectrum of silver permanganate
Authors: Jubert A. H. , Varetti E. L. , Baran E. J.
Published: May 2005

The resonance Raman spectrum of a polycrystalline sample of AgMnO4 allowed a wider insight into the vibrational properties of the MnO ion in this lattice. This study confirmed important covalent contributions to the overall structure and strong cooperative effects between the ions present in the unit cell.
Vibrational spectra of specifically deuteriated 2,2′‐bipyridine complexes of Fe(II), Ru(II) and Os(II)
Authors: McClanahan Stephen , Kincaid James
Published: May 2005

The resonance Raman spectra of specifically deuteriated divalent d6 metal complexes are reported. These include the iron(II) and ruthenium(II) perdeuteriated complexes and the Ru(bpy‐3,3′‐d2)32+ and Ru(bpy‐6,6′‐d2)32+ complex ions. The syntheses of the deuteriated ligands are reported and the frequency shifts observed on deuteriation are correlated with the natural abundance iron(II), ruthenium(II) and osmium(II) complexes.
Vibrational spectra and conformational behavior of (cyanomethyl)cyclopropane
Authors: Wurrey C. J. , Yeh Y. Y. , Weakley M. D. , Kalasinsky V. F.
Published: May 2005

The infrared spectra (4000–400 cm−1) of gaseous, liquid and solid (cyanomethyl) cyclopropane have been recorded for the first time. Additionally, the Raman spectra (3500–50 cm−1) of condensed phases of this substance have also been obtained. ‘Extra’ Q branches have been observed in the gas‐phase infrared spectrum, and six liquid‐phase Raman doublets (two of which are also seen in the infrared spectrum of the liquid) have also been observed, wherein one member of each doublet vanishes once the polycrystalline solid state spectrum is obtained. These data have been interpreted in terms of a two conformer (gauche/cis) fluid‐phase equilibrium for (cyanomethyl)cyclopropane, with only the gauche conformer remaining in the solid phase. The temperature behavior of the 774/756 and 835/855 cm−1 liquid‐phase Raman doublets yields an enthalpy difference between conformers of 0.72±0.10 kcal mol−1, with the gauche conformer the more stable. This ΔH value implies a room‐temperature conformational equilibrium for (cyanomethyl)cyclopropane composed of 87% gauche and 13% cis rotamers in the liquid phase. In addition, a vibrational assignment for the 33 normal modes of (cyanomethyl)cyclopropane has been proposed, and it is in excellent agreement with the previously published vibrational assignments for three (halomethyl)cyclopropanes.
Hydrogen bonding in hydrogen peroxide and water. A Raman study of the liquid state
Authors: Giguère Paul A. , Chen Hung
Published: May 2005

The Raman spectra of pure, anhydrous H2O2 and its deuteriated analogues, D2O2 and HDO2, were examined in the liquid state up to 40 °C and supercooled down to −75 °C. The OH (OD) stretching bands show a broad, single‐peaked contour, and a strongly temperature‐dependent asymmetry‐ Decomposition by analog computer reveals two overlapping bands, about 100 cm−1 apart, with different temperature behavior. In contrast with water, there is no indication in the hydrogen peroxide spectra of ‘free,’ i.e. non‐hydrogen‐bonded, OH groups, in keeping with the flexible geometry of the molecule and its electronic configuration. Based on these spectra, and by analogy with water, a two‐state model is proposed featuring a continuum of hydrogen‐bonded H2O2 molecules, with elose‐packed OH groups in two kinds of environments. The hydrogen bonds are slightly weaker (12–15%) than those in water. Hydrogen peroxide is the best analog for studying the structure of water.
Raman spectra of the III → II phase transition in normal (d0) and deuteriated (d12) tetramethylammonium chlorides
Authors: Pal Mahendra , Agarwal Anshu , Patel M. B. , Bist H. D.
Published: May 2005

A design of a high‐temperature cell (used with a Spex‐1403 Ramalog spectrophotometer) for Raman studies with 90° geometry is given. Raman spectra of normal (d0) and denteriated (d12) tetramethylammonium chlorides in phases III and II are reported, together with their assignments. On the basis of the temperature dependence of the thermosensitive bands, the III → II phase transition was found at 367 ± 2 K for normal (d0) tetramethylam monium chloride and at 407±5 K for deuteriated (d12) tetramethylammonium chloride. It is observed that the III → II phase transition is irreversible if the samples are kept under vacuum during the investigation. Traces of moisture present in the samples are responsible for the stability of the room‐temperature phase III.
Vibrational spectra of 4, 4′‐difluorobiphenyl‐d8 and the structure of biphenyls in solution
Authors: Pulham R. J. , Steele D.
Published: May 2005

4, 4′‐Difluorobiphenyl‐d8 was synthesized by two routes and its infrared and Raman spectra were recorded. These were analysed with the assistance of calculated frequencies using a force field based on fluorobenzenes and using phase effects. A perturbation treatment of the frequencies of biphenyl, of its 4, 4′‐difluoro derivative and of their fully deuteriated isotopomers yielded a refined force field essentially in accord with previous aromatic fields. By studying the changes in the frequencies of certain skeletal modes on going from crystal to solution, the dihedral angle of the difluoro compound was shown to be very similar to that of biphenyl itself in solution (35–40°). There is, however, a possibility that the present model underestimates the in‐plane B1g skeletal deformation mode. In this case the biphenyl dihedral angle will be slightly overestimated and that of 4, 4′‐difluorobiphenyl slightly underestimated (by up to 5°).
Raman intensities of lattice vibrations in naphthalene
Authors: Cardini G. , Schettino V.
Published: May 2005

The Raman intensities of lattice vibrations in crystalline naphthalene at room temperature have been calculated and compared with experimental results. The contribution of the local field and the effect of two‐centre representation of the molecular polarizability are discussed.
Raman, infrared, fluorine NMR spectra and rotational isomerism of perfluoromethyl oxalate
Authors: Cutín E. H. , Védova C. O. Della , Varetti E. L. , Aymonino P. J.
Published: May 2005

The Raman spectra of solid and liquid perfluoromethyl oxalate and its IR spectra in the gaseous, solution (CCl4) and solid phases have been recorded. The fluorine NMR spectrum of the substance in CCl4 solution has also been obtained. A comparison of the vibrational spectra in the solid and fluid phases shows that perfluoromethyl oxalate exists in the fluid phases as a conformational mixture, whereas in the solid phase it seems to exist as a single conformer of trans‐planar C24 structure. A band assignment has been attempted for the normal vibrational modes of this conformer.
Raman spectroscopic detection of a low‐temperature structural phase transition in distearoyl phosphatidylcholine bilayers
Authors: Madec C. , Wong P. T. T. , Mantsch H. H.
Published: May 2005

A new structural phase change at − 6 °C was found in aqueous dispersions of distearoyl phosphatidylcholine. The thermotropic gel‐gel phase transition at −6 °C exhibits first‐order characteristics and is equivalent to the barotropic phase transition on chain length is discussed.
Raman spectra and normal coordinate analysis of the planar vibrations of iron phthalocyanine
Authors: Melendres C. A. , Maroni V. A.
Published: May 2005

Raman spectra have been obtained for solid iron phthalocyanine and a 10−6 M solution of its tetrasulfonated derivative with Kr+ laser excitation using the 6471 Å line. A normal coordinate analysis was carried out to determine assignments for the observed frequencies in terms of the various Raman active planar modes of vibration of the complex. Good agreement was obtained between calculated and observed frequencies using an adjusted valence force field (AVFF) and incorporating empirical correlations for related types of force constants. The assignments of the normal modes of vibration appear to be generally consistent with other avilable experimental and theoretical information for phthalocyanine complexes and the related metalloporphins; however, the extensive mixing of the internal coordinates within the calculated normal modes shows clearly that the assignment of specific vibrational frequencies to individual internal coordinates is not justified. Rather, the vibrational kinematics appear to involve concerted motions of the various interior and exterior ring systems.
Theory of depolarization ratios in diatomic molecules for continuum resonance Raman scattering and application to 79Br2
Authors: Baierl P. , Kiefer W.
Published: May 2005

A theory is presented for the calculation of depolarization ratios of the Q‐branches of diatomic molecules for the case of resonance with continuous (dissociative and/or repulsive) excited electronic states. The theory was applied to the 79Br2 molecule and calculations of the depolarization ratios of the fundamental Q‐branch and accompanying hot bands were performed for different excitation frequencies. Comparison with experimentally obtained depolarization ratios showed good agreement.
Degree of circular polarization of resonance Raman scattering–luminescence discrimination and assignment of non‐totally symmetric modes in [Ph4P][ReS4]
Authors: Peacock Robert D. , Stewart Brian
Published: May 2005

The degree of circular polarization, C(π), has been measured for resonance Raman scattering from the [ReS4]− ion in a microcrystalline sample at 10 K. There is considerable partially relaxed luminescence which is discriminated against by this technique. The relative values of C(π), observed for components of resonantly enhanced Raman bands, provide evidence for assignments to non‐totally symmetric modes of the ion.
Raman intensities and electro‐optical parameters of the azide ion in β‐NaN3 single crystals and aqueous solution
Authors: Bertsch Gerhard , Rösinger Gerold , Eysel Hans H.
Published: May 2005

Raman spectra of oriented β‐NaN3 single crystals were taken in b(cc)a, b(cb)a, a(bb)c and a(ba)c orientations. Because of the simple structure R3m (Z = 1), the observed intensities can be interpreted on the basis of an oriented gas model. A new assignment is given for the weak bands: 1278 cm−1 (Eg of 2ν2), 1269 cm−1 (A1g of 2ν2), 1260 cm−1 (A1g of 030←010), 1368 cm−1 (110←010). Electro‐optical parameters and first‐order bond moments are calculated for the NN bonds: a∥=3.47 Å2, α′⊥=1.33 Å2, μ=0.57 D, dμ/dr=8.34 D Å−1.
Analyse Vibrationnelle et Structurale en Série Aliphatique Saturée VI–Spectres de Vibration de l'acide Diéthylmalonique et de ses sels Alcalins en Solution Aqueuse
Authors: Delarbre J. L. , Maury Bardet L. Et L.
Published: May 2005

Les spectres Raman et infrarouge de l'acide diéthylmalonique et de ses sels alcalins en solution aqueuse (H2O et D2O) ontété étudiés dans le domaine 3500‐200 cmminus;1. L'analyse du facteur de dépolarisation des raies Raman nous permet de conclure que l'acide diéthylmalonique et le sel neutre, comme I'acide diméthylmalonique et son sel neutre, appartiennent au groupe de symétrie C2 tandis que le sel acide répond au groupe Cs; I'existence d'une liaison hydrogéne intramoléculaire dans le sel acide est discutée. Une attribution des vibrations fondamentales est proposée.
Hyper‐Raman spectra and polariton‐vibration resonances in liquid C2Cl4 and PCl3
Authors: Denisov V. N. , Mavrin B. N. , Podobedov V. B. , Sterin Kh. E.
Published: May 2005

The polarized hyper‐Raman spectra and the polaritons were studied in liquid PCl3 and C2Cl4. The TO‐LO splitting of the dipole modes was found in PCl3 [480 (TO)‐515 (LO) cm−1 and 494 (LO)‐500 (TO) cm−1]. The LO and TO mechanical modes vanished in the back‐scattering and forward‐scattering hyper‐Raman spectra, respectively. The possibility of observation of the splitting due to polariton‐vibration resonance is analysed. It is shown that the observation at ω≲300 cm−1 is possible if the oscillator strength of the vibration exceeds 0.1. Using the value of the splitting, the oscillator strengths were estimated for a number of dipole modes in PCl3 and C2Cl4. The trend of the polariton branches and the observation of the resonances showed that all dipole modes of a liquid have the same symmetry, although the symmetry of these modes was different when considered in terms of the 'molecular' selection rules. To analyse the selection rules of the vibrational spectra of liquids it is necessary to invoke its macroscopic symmetry.
Excitation profiles and depolarization ratios of some prominent Raman lines in oxyhaemoglobin and ferrocytochrome c in the pre‐resonant and resonant region of the Q‐band
Authors: Schweitzer‐Stenner R. , Dreybrodt W.
Published: May 2005

The depolarization ratio‐dispersion curves and the excitation profiles of oxyhaemoglobin (1375, 1583, 1638 cm−1) and ferrocytochrome c Raman lines have been measured in the pre‐resonant and resonant regions of the Q‐band, respectively. The experimental data are interpreted by fifth‐order Loudon theory of the polarizibility tensor, including symmetry lowering of the haem group and the creation and subsequent annihilation of a second phonon. The fitting constants needed to fit the experimental data are related to vibronic coupling matrix elements due to the Raman and the second phonon. They also contain distortions δQΓ, lowering the ideal D4h, symmetry of the functional haem group. These distortions can be classified due to the Raman‐allowed representations A1g, B1g, B2g and A2g in D4h symmetry. Thus, from the fitting procedure one obtains detailed information about the actual symmetry of the haem group.
The use of compacted metal discs to measure Raman spectra
Authors: Nimmo J. A. , Bovill A. J. , McConnell A. A. , Smith W. E.
Published: May 2005

Compacted discs prepared from a mixture of finely divided particles of a compound diluted in a large excess of metal powder facilitate the measurement of Raman spectra for some compounds which give poor scattering by conventional techniques. The method is most useful with coloured compounds. The advantages include simplicity, increased signal‐to‐noise ratio by factors of up to 1000 and decreased or altered fluorescence. The effect appears to be caused mainly by small crevices in the compacted metal surface which act as internal mirrors to produce many small multiple‐reflection cells, but there is also evidence of an electronic interaction with the metal surface. Silver, aluminium and copper matrices were studied, silver being found to be the most advantageous, although aluminium under certain conditions may also be effective.
The resonance Raman spectra of some cyanine dyes
Authors: Yang J.‐P. , Callender R. H.
Published: May 2005

The resonance Raman spectra of a series of cyanine dyes, with various lengths of the methine chain, have been obtained. This series consists of the 1,1′‐diethyl‐2,2′‐quino group basic structure. Raman spectra of some dyes with closely related structures were also measured. The Raman bands are assigned to normal modes arising from particular molecular moieties. For comparison purposes, the IR spectra of these dyes are also presented.
Effect of the damping constant on Raman excitation profiles
Authors: Lee Soo‐Y. , Chow King‐Sum
Published: May 2005

Raman scattering is treated using the displaced harmonic oscillator model. The time‐dependent approach to the Raman scattering tensor was adopted and the exact propagation of gaussians on harmonic surfaces was exploited. An insight into the effect of the damping constant on the Raman excitation profiles was thus obtained. It is shown that the dynamics of the wavepacket propagation on the excited state surface governs the difference between continuum resonance Raman scattering and discrete resonance Raman scattering.
Raman spectra of I4O9 formed by the reaction of iodine with ozone
Authors: Sunder S. , Wren J. C. , Vikis A. C.
Published: May 2005

The Raman spectrum of I4O9, formed by the gas‐phase reaction of I2 with O3, has been measured. Freshly prepared samples of I4O9 gave broad band spectra characteristic of an amorphous solid. Vibration bands at 780, 740, 620 and 450 cm−1 were observed. It was established conclusively that I4O9 is a distinct molecular species and not a mixture of I2O5 and I2O4.
Raman difference spectroscopy via backscattering from a spinning tube and from a low‐temperature tuning fork
Authors: Eng John F. , Czernuszewicz Roman S. , Spiro Thomas G.
Published: May 2005

Two novel devices for difference Raman spectroscopy are described. In one, an NMR tube is fltted with a PTFE divider to permit difference spectroscopy via the convenient spinning tube backscattering arrangement. The other device is a tuning fork, equipped with a pair of sample cups, attached to a cold finger, to permit acquisition of difference spectra on small samples of frozen solutions. This provides a particularly convenient method for low‐temperature difference spectroscopy.
Molecular reorientation of liquid trimethylchlorosilane from Raman band shape studies
Authors: Steiger Th. , Brzezinka K.‐W. , Reich P.
Published: May 2005

Molecular reorientation of liquid trimethylchlorosilane (TMC) has been studied by means of Raman band shape analysis for the temperatures 298, 246 and 218 K. Experimental correlation times were compared with NMR relaxation time measurements and with diffusional and hydrodynamic models. Information theory was used to predict C(1)(t) given C(2)(t).
Raman spectra of the human lens in relation to pathology and the anticataract effect of drugs
Authors: Bertoluzza A. , Fagnano C. , Monti P. , Caramazza R. , Cellini M.
Published: May 2005

Raman spectroscopy has been used for ophthalmological studies. Results obtained with traditional Raman instrumentation on animal and human lenses (normal and cataracted) and on the action of anticataract drugs are presented and discussed.
High‐resolution Raman investigation of the vibrational relaxation of two‐phonon bound states in solid CO2 at different temperatures
Authors: Ranson P. , Ouillon R. , Califano S.
Published: May 2005

The Raman spectra of the bound states Ω+ and Ω− of the Fermi diad ω1:2ω2 in crystalline CO2 have been measured at several temperatures under very high resolution. Band profiles have been determined for each of the two factor group components, one Ag and one Fg, of the two states.

The evolution with temperature of the bandwidths has been interpreted in terms of four‐phonon decay processes. A single down‐process, involving a lattice phonon at 60 cm−1, is shown to be sufficient to reproduce the experimental data for the Ω+ state. In the same way, a single up‐process, involving the same lattice phonon, is sufficient to fit the experimental data for the Ω− state. The variation of the factor group splitting of the Ω− component as a function of temperature has also been determined.
Coherent Raman spectroscopy of glyoxal vapour
Authors: Duval A. B. , King D. A. , Haines R. , Isenor N. R. , Orr B. J.
Published: May 2005

The coherent Raman spectroscopic techniques CARS and PARS have been used to study glyoxal (C2H2O2) in the vapour phase. The following fundamental vibrational frequencies for trans‐glyoxal have been determined: ν1 = 2840 ± 2, ν2 = 1742.5 ± 0.5 and ν3 = 1353.5 ± 0.5 cm−1. Several hot and combination bands have also been identified. The rovibrational contour of the ν2 band is unexpectedly broad and structured and a variety of possible sources of this apparent anomaly are investigated. Novel experimental strategies include simultaneous recording of CARS and PARS spectra, major variations of pump and Stokes wavelengths to eliminate resonantly enhanced processes and rotationally resolved Raman–optical double resonance spectroscopy.
Vibrational spectra and structure of halogen‐substituted cyclopropanes. III—cis‐ and trans‐1, 2‐diiodocyclopropane
Authors: Schrumpf G.
Published: May 2005

The infrared spectra of liquid cis‐ and trans‐1, 2‐diiodocyclopropane were measured from 4000 to 200 cm−1. Raman spectra between 4000 and 50 cm−1 of the two compounds as liquids and of the solid cis isomer were also obtained. All of the 21 normal vibrations of the two molecules were convincingly assigned on the basis of Raman depolarization ratios and group frequency correlations. Comparisons are made with the normal modes of related compounds. There is excellent agreement with those assignments previously proposed for the two isomers of 1, 2‐dibromocyclopropane, cis‐1, 2‐dichlorocyclopropane and related modes of iodocyclopropane.
Intensity measurement of resonance Raman spectra of adsorbed dyes by the divided disc method
Authors: Tsukamoto Ikuko , Machida Katsunosuke
Published: May 2005

The divided disc method was utilized for the measurement of the resonance Raman intensities of adsorbed dyes. Only one band of crystal violet exhibits appreciable change in its relative intensity when adsorbed on silica gel. The spectral features of the adsorbed crystal violet are similar to those reported for the SERS spectrum of the dye adsorbed on a silver electrode. The resonance Raman spectrum of the adsorbed methyl orange resembles that of the protonated dye crystallized from acidic solution, but the intensities are considerably enhanced on adsorption. From the spectral pattern, the adsorbed methyl orange was proved to take the same azonium form as was reported as the SER scatterer. The Raman scattering coefficients of the CC stretching band of methyl orange excited at 488.0 and 514.5 nm were proved to be enhanced on adsorption of silica gel by factors of ca 50 and 100, respectively.
FT‐IR and micro‐Raman spectra of some group IVB and VIB organometallacyclo‐sulfanes and ‐selenanes
Authors: Butler Ian S. , Harvey Pierre D. , McCall James M. , Shaver Alan
Published: May 2005

The FT‐IR and micro‐Raman spectra of the solid Group IVB and VIB metallacyclo‐sulfanes and ‐selenanes, Cp2ME5 (Cp = η‐C5H5; M = Ti, Zr, Hf; E = S, Se), (η‐C5Me5)2MS3, Cp2MS4 (M = Mo, W) and Cp2MoS2 have been recorded and assignments are presented for the cyclopentadienyl ligand vibrations and some of the low‐energy modes associated with the metal‐chalcogen moieties. This is the first time that attempts have been made to identify the ZrS, HfS, TiSe, ZrSe, and HfSe stretching modes in such metal chelates. For the polysulfane complexes, the peaks attributed to the symmetric ν(SS) stretching modes decrease in energy with increasing size of the catenated metal‐sulfur ring and so it appears that vibrational spectroscopy can be used to distinguish between the four different ring sizes. For the polyselenanes, an empirical relationship (similar to that already known for S‐S vibrations) relating the wavenumber of the symmetric ν(SeSe) stretch and the Se‐Se bond length is proposed.
Infrared and Raman spectra of 2,3‐dimethylaniline
Authors: Shukla A. R. , Pathak C. M. , Dongre N. G. , Asthana B. P. , Shamir Jacob
Published: May 2005

The infrared spectra of 2,3‐dimethylaniline in different phases have been recorded in the region 4000–100 cm−1. In the solid phases at 223 and 123 K, however, the spectra were recorded in the region 4000–400 cm−1 only. Raman spectra with polarization measurements have been recorded and investigated for the first time. New frequency assignments are proposed, assuming the molecule to possess an approximate Cs symmetry; 52 out of a possible 54 normal modes in the molecule have been observed and assigned, including 25 hitherto unreported modes. The observed spectral changes give evidence of a solid‐solid phase transition in the molecule between 223 and 123 K and indicate the presence of intermolecular hydrogen bonding due to the presence of an amino group in the molecule.
Raman spectra of orthorhombic sulfur at 40 K
Authors: Harvey Pierre D. , Butler Ian S.
Published: May 2005

High–quality Raman spectra of orthorhombic sulfur (S8) have been recorded at 40 K employing multiscanning conditions. Assignments are proposed for the many new features detected, especially binary and ternary overtones and combinations of the SS stretching and SSS bending vibrations. The anharmonicities of these particular modes are shown to be fairly small.
Incommensurate phase in tetramethylammonium tetrachlorozincate: Evidence from internal modes
Authors: Pal Mahendra , Agarwal Anshu , Khandelwal D. P. , Bist H. D.
Published: May 2005

Temperature‐dependent vibrational Raman studies of tetramethylammonium tetrachlorozincate [(TMA)2ZnCl4] are reported together with the assignments of the observed bands in all the six polarization geometries at room temperature in phase I, which is orthorhombic with a space group D2h16 (Z=4). Existence of the well known incommensurate phase with wave vector κ = 2/5+δ in the temperature range 296.6–280.9 K is supported by the abnormal intensity behaviour of modes of species A1 (under the point group symmetry Td for TMA and ZnCl4 ions) in X(ZZ)Y and X(YZ)Y polarization geometries. The observed intensity behaviour could be explained on the assumption that the orientations of TMA and ZnCl4 ions are governed by the incommensurate modulation in the Z‐direction.
Analyse Vibrationnelle et Structurale en Série Aliphatique insaturée–Spectres de Vibration de l'Acide Acétylènedicarboxylique et de ses Sels Alcalins en Solution Aqueuse
Authors: Delarbre Jean Louis , Maury Luc , Bardet Lucette
Published: May 2005

Les spectres Raman et infrarouge des acides acétylènedicarboxylique H2C4O4 D2C4O4 et de leurs sels alcalins KHC4O4, KDC4O4 et K2C4O4 ont été enregistrés de 3000 à 200 cm−1. L'analyse du facteur de dépolarisation nous a permis de conclure que I'acide, le sel acide et le sel neutre sont de symétries respectives C2h, CS et D2d. Une comparaison des conformations avec celles déterminées en série oxalique a été réalisée. Une attribution des vibrations fondamentales est proposée.
Fluorescence rejection in Raman spectroscopy using a gated intensified diode array detector
Authors: Everall N. , Jackson R. W. , Howard J. , Hutchinson K.
Published: May 2005

A system consisting of a mode‐locked and cavity‐dumped picosecond laser and gated (5 ns) intensified diode array detector has been used to evaluate the potential of diode arrays as detectors in fluorescence rejection measurements of Raman spectra. Successful fluorescence rejection was observed, but both the level of rejection and the signal‐to‐noise improvement observed would be substantially improved if the operating characteristics of the laser system and of the array were different. It was demonstrated that the diode array opens several times, at intervals of ca 15.5 ns, for each trigger pulse supplied.
The pure rotation Raman spectrum of 17O18O
Authors: Edwards H. G. M. , Long D. A. , Najm K. A. B.
Published: May 2005

The pure rotation Raman spectrum of 17O18O has been recorded photographically using laser excitation and a spectrograph with a reciprocal linear dispersion of 1.4 cm−1 mm−1 at 488.0 nm. The following B0, D0 and r0 values were obtained; B0=1.31546±0.00002 cm−1, 106D0=3.50±0.05 cm−1 and r0=121.072±0.002 pm.