bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low frequency Raman bands and space symmetries in sym‐tetrachlorobenzene
Authors: Lin C. T. , Pessine F. B. T. , Srivastava R. , Katiyar R. S. 
Published: May 2005

AbstractThe external Raman active vibrational modes for sym‐tetrachlorobenzene single crystals have been recorded at different low temperatures. Accurate temperature dependent Raman measurements on frequencies and on relative intensities show that tetrachlorobenzene suffers a phase transition at T0 = 160 ± 5 K. Group theoretical Correlation indicates that if the low temperature phase of tetrachlorobvenzene (α phase) is P1 symmetry, then one should observe nine lattice modes in the Raman spectrum; likewise, one should observe only six modes if the space symmetry of the β phase tetrachlorobenzene is P1. The fact that we do not see more than six external Raman peaks at lower temperatures suggests that the low temperature phase symmetry should be P1 for tetrachlorobenzene.
A laser Raman spectroscopic study of the product formed in the reaction of phosphoryl chloride with N,N‐dimethylformamide and with N,N‐dimethylbenzamide
Authors: Scheuermann W. , McGillivray G. , White J. 
Published: May 2005

AbstractThe Raman spectra of POCl3, HCONMe2, PhCONMe2 and reaction mixtures of POCl3 and HCONMe2, and POCl3 and PhCONMe2 have been recorded in an attempt to establish the nature of the reaction products. Assignments for most of the bands observed in the spectra of the reaction product are given. The spectra were compared with the spectra of the products of the reaction between HCONMe2 and SOCl2. Several arguments could be advanced which indicated that the only product (RP1) formed in the reaction of POCl3 with HCONMe2 was \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm HCOPOCl}_{\rm 2} \mathop {\rm N}\limits^{\rm + } {\rm Me}_{\rm 2} {\rm Cl}^ - $\end{document} rather than \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm HCCI}\mathop {\rm N}\limits^{\rm + } {\rm Me}_2 {\rm OPOCl}_2^ - $\end{document}. The observed accidental degeneracy of the amide I band at 1668 cm−1 in RP1 and the imine band at 1665 cm−1 in \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm HCCI}_{\rm 2} \mathop {\rm N}\limits^{\rm + } {\rm Me}_{\rm 2} {\rm Cl}^ - $\end{document} showed that the usefulness of the amide I and imine bands as characteristic bands is restricted.
Raman spectra and lattice vibrations in single crystals of potassium acid phthalate
Authors: Krishnamurthy N. , Soots V. 
Published: May 2005

AbstractRaman scattering from single crystals of potassium acid phthalate has been observed with the 4880 Å and 5145 Å excitations of an argon ion laser. The room temperature Raman spectra, recorded with a Jarrel‐Ash spectrometer, in the region 0–300 cm−1, exhibit broad bands which are attributed to the translatory and rotatory types of lattice vibrations of the potassium and acid phthalate ions in the crystal. Experiments were carried out at 77 K using a Spex double monochromator and the Raman scattering in the second‐order of the gratings were observed. The result was a splitting of the several broad bands into their components. Assignments of these low frequency Raman spectra, consistent with the crystal structure and the group theoretical predictions is given. Variations in intensities of some of the spectra due to crystal orientation are also observed and briefly discussed.
Raman spectra and phase transition of ammonium uranyl nitrate
Authors: Caville C. 
Published: May 2005

AbstractRaman spectra of single crystals of NH4UO2(NO3)3 are recorded for the temperature range 293–6 K. In various orientations the room temperature spectra are similar to the corresponding isomorphous rubidium and caesium salts. As the crystal is cooled the changes in the Raman spectra indicate a phase transition due to an ordering of the ammonium ions.
Raman spectra from adsorbed iodine species on an unroughened platinum electrode surface
Authors: Cooney R. P. , Hendra P. J. , Fleischmann M. 
Published: May 2005

AbstractRaman spectra are reported of potential dependent surface species on an unroughened platinum electrode in 1.0 M H2SO4, 10−3 M KI. The results obtained using signal‐averaging and ‘line imaging’ of the laser are contrasted with previously reported spectra obtained using platinized high‐surface‐area electrodes and ‘spot imaging’ of the laser. Spectra are interpreted in term of ‘crystal‐like’ and ‘gas‐like’ I2 and adsorbed I−3 on the surface of the platinum electrode.
Resonance Raman spectrum of β‐carotene
Authors: Sufrà S. , Dellepiane G. , Masetti G. , Zerbi G. 
Published: May 2005

AbstractResonance Raman spectra for β‐carotene in carbon disulphide at room temperature have been measured. The experimental absorption spectrum and excitation profiles were analysed using a three‐dimensional model involving several molecular parameters related to the excited state's structure. These parameters are quite different from those reported previously in the literature. A possible explanation for this discrepancy is proposed.
Spectres de Vibration et Structure de l'Octamethylcyclotetrasilazane [(CH3)2SiNH]4 dans les Etats Gazeux, Liquide et Cristallin
Authors: Imbenotte M. , Palavit G. , Legrand Ep. , Huvenne J. P. , Vergoten Et G. 
Published: May 2005

AbstractInfrared and Raman spectra of octamethylcyclotetrasilazane [(CH3)2SiNH]4 are reported for the compound in the gaseous and liquid states and for solutions in CCl4. 21 Raman bands have been observed for the first time. They are assigned on the basis of group frequencies. Their temperature dependence does not reveal any favoured conformation. Raman spectra of both polycrystalline powders and single crystals are well explained if the existence of chair and boat forms is assumed, according to X‐ray results.
Excited state (excitation) interactions in polyene aggregates. Resonance Raman and absorption spectroscopic evidence
Authors: Salares V. R. , Young N. M. , Carey P. R. , Bernstein H. J. 
Published: May 2005

AbstractThe carotenoids astaxanthin, lutein and zeaxanthin form high molecular weight aggregates in aqueous solvent systems. The absorption spectra of the aggregates, compared to those of the monomer molecules, show significant bandwidth narrowing and blue shifts of 600–800 Å. The resonance Raman spectra of these aggregated polyenes are anomalous in that ν CC occurs near 1518 cm−1 whereas a well‐established νCC vs 1/λmax correlation predicts that νCC should be near 1560 cm−1. The Raman and absorption data together demonstrate that strong excited state interactions are taking place and these results illustrate the utility of the resonance Raman technique for recognizing excited state perturbations. Raman excitation profiles (the variation of Raman intensity with wavelength) on aggregated astaxanthin and low temperature (−100 °C) absorption spectra on aggregates of astaxanthin and lutein establish that a pronounced change in vibronic structure occurs upon aggregation. In contrast to astaxanthin or lutein monomers whose electronic absorption spectra are made up of 0–0, 0–1, 0–2,… transitions, only the 0–0 transition is seen in the aggregates. The results are explained in terms of the molecular exciton model.
Solved and unsolved problems in the Raman spectrum of S in KI single crystals
Authors: Holzer W. , Racine S. , Cipriani J. 
Published: May 2005

AbstractThe orientational dynamics is studied by the Raman spectrum of the ground state molecules S and is found to be isotope selective. The Raman spectrum of S molecules in the excited state 2Πu and in another tentatively assigned state is presented.
High‐pressure variable temperature Raman studies on hexamethyl benzene crystals
Authors: Bodenheimer J. S. , Sherman W. F. , Wilkinson G. R. 
Published: May 2005

AbstractThe Raman spectra of hexamethyl benzene and HMB‐d18 have been recorded as a function of temperature between 4 K and 400 K and as a function of pressure up to 8kbar. In the low‐frequency region, librational and torsional modes have been distinguished. The spectra indicate a phase transition to a high‐pressure phase IV. The polarized infrared spectra of single crystals have also been observed at different temperatures.
Diffusion Raman des Acides Pivalique Hydrogéné et Déutérie en Phase Liquide et en Solution
Authors: Longueville W. , Fontaine H. 
Published: May 2005

AbstractRaman spectra have been recorded for d0, d1 and d9 pivalic acids and pivalic anhydride in the liquid phase and in solution in CCl4. A complete assignment of the bands is proposed and discussed specially in relation to dimerization and eventual breaking of dimers. The potential energy for hindered rotation of the CH3 groups is calculated.
Configurational equilibria of trihalogeno complexes of mercury (II) in amide solvents
Authors: Waters D. N. , Kantarci Z. , Rahman Nazmun N. 
Published: May 2005

AbstractSolutions containing the ions HgCl or HgBr in N,N′‐diethylformamide, N,N′‐dimethylacetamide, N,N′‐diethylacetamide and hexamethylphosphoramide give Raman spectra indicative of the presence of two structurally distinct forms of these ions in equilibrium. These are interpreted as being configurational isomers HgX (unsolvated, of D3h symmetry) and SHgX (having one coordinated solvent molecule and possessing essentially C3ν symmetry), respectively.
Second order Raman spectrum of rutile TiO2
Authors: Nicola J. H. , Brunharoto C. A. , Abramovich M. , Conçalves da Silva C. E. T. 
Published: May 2005

AbstractData are presented on the second order Raman spectrum of rutile TiO2 for various scattering geometries, at room and liquid N2 temperatures. The results of a standard critical point analysis (i) allow the most important addition processes at low energies to be identified, (ii) indicate the importance of matrix element effects, and (iii) cannot account for a peak at 172 cm−1 for the Y (xy) X geometry.
Laser Raman inelastic light scattering investigations of hyaluronic acid primary and secondary structure
Authors: Barrett T. W. , Peticolas W. L. 
Published: May 2005

AbstractThe solvent‐subtracted Raman spectrum of hyaluronic acid is reported. The spectrum is unchanged by (i) variations in the pH of the solution 6.0–8.5, when buffered at constant ionic strength 0.1, and (ii) changes in temperature 10–50°C.As rheological, flow birefringence, and linear dichroism studies of hyaluronate solutions indicate a large and abrupt structural transition across the physiological pH range 7.0–7.5, the negative finding reported here is of considerable interest in contrast with those previous studies. When considering the polysaccharides in general, as precise rheological, flow birefringence and linear dichroism data are only available for hyaluronic acid, the present finding is of interest for hyaluronic acid considered as a model polysaccharide system exhibiting elasticity.The result reported here is discussed within the context of, on the one hand, the possible limitations of the Raman technique which is a probe of g‐state vibrational modes and, on the other hand, the possible extension of the Raman technique to probing oriented (stressed) samples. As a previous study demonstrated a small limiting birefringence but a large limiting extinction angle with minimum change in monomer anisotropy for these solutions, the suggestion is favored that the abrupt structural transition across the physiological pH range previously reported is due to long‐range Van der Waals interactions.
Spectres Raman de Résonance de Dérivés Parasubstitués de l' Azobenzène
Authors: Lorriaux J. L. , Merlin J. C. , Dupaix A. , Thomas E. W. 
Published: May 2005

AbstractResonance Raman spectra of twenty parasubstituted azobenzene derivatives are compared, enabling a more complete assignment of bands to be made. Since all the spectra are rather similar, the various ring substituents are not resonance Raman active, and all the observed bands can be assigned to vibrational modes of the aromatic rings and to the azo group itself. Frequency shifts in the PhN stretching region are opposite to those expected based on delocalization along the PhNNPh moiety. From the complexity of band pattern around the NN stretching region and from the above described frequency shifts, several types of vibrational coupling are evident. On the basis of the band assignments, some useful conclusions can be reached for interpreting the observed spectral changes when azobenzene derivatives are used as chromophore probes in biochemical system studies.
Raman and infrared spectra of potassium nitrilosulphonate dihydrate, K3N(SO3)3 · 2H2O, and its 15N derivative: A normal coordinate analysis of the ion, N(SO3)
Authors: Hall John R. , Johnson Robert A. , Shurvell Herbert F. 
Published: May 2005

AbstractThe infrared and Raman spectra (4000–50 cm−1) of polycrystalline K3N(SO3)3·2H2O have been recorded at 77K. Spectra of the 15N derivative, the anhydrous salt, an aqueous solution of the soluble sodium salt and K3N(SO3)3·2D2O have also been recorded. A normal coordinate analysis was applied to predict the 14N/15N isotopic frequency shifts. The potential energy distribution indicated extensive mixing of the normal modes. The NS symmetric stretch is predicted to occur at 276 cm−1 (kNS = 3.1 mdynes Å−1) and a Raman band at 293 cm−1 in the solid state spectrum is assigned to this mode. NS antisymmetric stretching occurs at 912 and 887 cm−1 (888 and 861 cm−1 for 15N). The 14NS3 out‐of‐plane bending mode is mixed with NSO bending in features observed at 872 and 165 cm−1. The SO3 groups show characteristic group frequencies.
Resonance Raman spectra of insoluble monolayers spread on a water surface
Authors: Takenaka Tohru , Fukuzaki Hiroko 
Published: May 2005

AbstractResonance Raman spectra of insoluble (or spread) monolayers of cetyl orange on a water surface have been obtained by the use of a total reflection method previously proposed. The spectra of the monolayers resemble that of solid cetyl orange rather than that of the chloroform solution, suggesting that the structure of cetyl orange in the monolayer is similar to that in the solid state. From polarization measurements of the spectra, the molecular orientation in the monolayers has been examined at various surface pressures. The molecules in the insoluble monolayers show a higher orientation with respect to the vertical axis as compared with those in soluble (or adsorbed) monolayers. The degree of molecular orientation rises with an increase in surface pressure of the monolayers but decreases considerably upon collapse.
Resonance Raman spectra of sulfophthalein dyes in aqueous solutions
Authors: Machida Katsunosuke , Lee Hohi , Uno Toyozo 
Published: May 2005

AbstractResonance Raman spectra of nine sulfophthalein dyes have been measured in aqueous solutions at various pH values between 4.0 and 11.0. Raman band assignments have been carried out by referring to the spectra of related compounds and the band shifts of Phenol Red on deuteration of the two phenol rings. The phenolsulfophthalein dyes have been ascertained to exist as a pure quinoid form in the weakly acidic solution, while in the alkaline solution they exist as a resonance hybrid of the quinoid and phenolate structures.
Determination by Raman spectroscopy of the solvation number of the chloride ion in liquid hydrogen chloride
Authors: Desbat B. , Huong P. V. 
Published: May 2005

AbstractSolutions of various concentrations of tetramethylammonium chloride and trimethylammonium chloride in liquid hydrogen chloride have been examined by Raman spectroscopy and the solvation number of Cl− anions in these solutions determined. It was found for solutions up to 3 mol I−1 of (CH3)4N+Cl− in liquid HCl, that the Cl− anions are solvated by six HCl molecules, while trimethylammonium chloride exists in the form of ion pairs solvated by five HCl molecules, (CH3)3N+H ⃛Cl−, 5HCl.
The presence of graphitic carbon in thin films of magnesium oxide as detected by surface Raman spectroscopy
Authors: Brown N. M. D. , Nelson W. J. , Cook B. , Louden J. D. 
Published: May 2005

AbstractHere is reported for the first time using surface laser Raman spectroscopy the presence of graphitic carbon in thin films (50–100 Å thick) of inagnesium oxide grown directly on magnesium metal by both thermal and d.c. plasma oxidation. The two characteristic and identifying bands are located at 1330 and 1615 cm−1.
Raman and infrared study on the effects of dimethylsulphoxide (DMSO) on water structure
Authors: Bertoluzza A. , Bonora S. , Battaglia M. A. , Monti P. 
Published: May 2005

AbstractRaman and infrared spectra of liquid dimethylsulphoxide (DMSO) and DMSO‐water mixtures in a wide range of concentrations are reported and discussed. It is found that changes in the vibrational spectra can be related to a gradual insertion of water molecules in the cluster structure of liquid DMSO. In the more dilute aqueous solutions a gradual lowering of the νs=0 stretching frequency is observed and this can be related to the cooperative character of DMSO–water interactions. The interpretation of the spectra is in agreement with the capacity of DMSO for ‘breaking’ the structure of water in the more concentrated aqueous solutions and ‘enhancing’ it in very dilute solutions.
Vibrational study of phase transitions in (NH3(CH2)3NH3)MnCl4
Authors: Sourisseau C. , Lucazeau G. 
Published: May 2005

AbstractInfrared and Raman spectra (10–4000 cm−1) of single crystals and of polycrstalline samples of (NH3(CH2)3NH3)MnCl4 and of its ND3 deuterated derivative have been investigated in the 10–400 K temperature range. An assignment of most of the observed bands is proposed. The first‐order phase transitions at 306 K and 336 K have been characterized. The spectra of the room temperature phase (III) and of the high temperature phase (I) differ mainly in the broadness of the bands and it is concluded that their structures can be similar. A strong perturbation of the chlorine lattice is observed at 306 K and 100 K. A systematic temperature dependence study (10–300 K) of the frequencies, ν, and half‐widths, Δν, of the low frequency Raman bands has been performed; it has been concluded that at about 110 K a large proportion of NH3 groups are jumping and that the activation energy, E0 ≃ 1.0 kcal mol−1, extracted from the curves Δν = f(T), is of the same order of magnitude as the potential barrier, V6 = 1.2 kcal mol−1, calculated from the torsional frequency of NH (329 cm−1) or of ND (245 cm−1). The NH3 torsional motions coupled with librations of alkylene chains are believed to be responsible for disorder observed among most of the modes. The low temperature spectra have been interpreted assuming D2h factor group and Z = 2 (i.e. the same as at room temperature) and they can be interpreted as if the sample was ordered, suggesting the possible existence of an ordered low temperature phase IV.
Raman spectral study of NbCl5 in chloroaluminate melts
Authors: Huglen R. , Mamantov G. , Smith G. P. , Begun G. M. 
Published: May 2005

AbstractThe Raman spectra of NbCl5 dissolved in AlCl3–NaCl and AlCl3–KCl melten and molten Al2Cl6 have been examined as a function of melt composition, temperature, and NbCl5 concentration. The results are compared with previously published data. The binary AlCl3–NbCl5 system at ∼200°C contains noninteracting NbCl5, Nb2Cl10 and Al2Cl6 molecules. The complexes formed when NbCl5 is dissolved in AlCl3–MCl (MNa and K) melts depend on acidity and temperature: NbCl is present only in very basic melts; NbCl5 is stable in basic and acidic melts; Nb2Cl10 is found only in acidic melts. High temperature favors formation of NbCl5 while low temperature stabilizes Nb2Cl10.
Raman study of phase transition and dynamic structure of solid CCl4
Authors: Ebisuzaki Y. 
Published: May 2005

AbstractA high pressure Raman study of CCl4 II and CCl4 III and the changes in the Raman activity at the II–III phase transition at 300 K are reported. The spectrum of CCl4 II is characterized by low intensity lattice bands and by the presence of sidebands on both the low and high energy side of the internal modes, ν2 and ν4. The sideband structure becomes Raman inactive and the lattice bands increase in intensity at the II–III phase transition; however, the major lattice peaks appear to be Raman active in both phases. It appears that there are some orientationally disordered molecules in CCl4 II. On the other hand, CCl4 III is an ordered phase.
Light scattering from phonons and magnons in CoCl2 · 2H2O
Authors: Helms C. A. , Scott J. F. , Toms D. J. 
Published: May 2005

AbstractA light scattering study of cobalt chloride dihydrate is reported. Emphasis is placed upon phonon–magnon interactions in the antiferromagnetic phase. Data taken at T = 1.6 K and magnetic fields from 0 to 5 T confirm the conclusion of Schneider and Weitzel that the ferrimagnetic–antiferromagnetic phase transition is first‐order and that a large hysteresis is observable at temperatures below 4.2 K.
Magnetoelastic waves and a group‐theoretical determination of selection rules for magnon—phonon interactions and two‐magnon Raman scattering in FeCl2 · 2H2O and CoCl2 · 2H2O
Authors: Cracknell A. P. 
Published: May 2005

AbstractIn this paper we deduce selection rules for magnon–phonon coupling at k0 and for lines of symmetry passing through k0 for the antiferromagnetic materials FeCl2 · 2H2O and CoCl2 · 2H2O. The results are tabulated. We also determine the symmetries of two‐magnon states in these materials and deduce selection rules for the Raman activity of these states. It is found that all the two‐magnon states are Raman active in each material, although there are some restrictions on the polarizations.
Spectres Raman des Modes Transverses et Longitudinaux à 293 K et 83 K et Spectres de Réflexion Infrarouge à 293 K et 83 K et Spectres de Réflexion Infrarouge à 293 K d'un Monocristal de Phosphite de Lithium, LiH2PO3
Authors: Beys Louis , Hillaire Paul , Cadène Michel 
Published: May 2005

AbstractThe Raman spectra of oriented single crystals of 7LiH2PO3 and 6LiH2PO3 at 293 K and 83 K are reported and compared. 6Li/7Li substitution was used to identify the translational modes of the lithium atoms. Bands with a lithium isotopic shift of 3–6% are observed in the 300–500 cm−1 region. The spectra of the 6LiH2PO3 single crystal indicate a coupling between the lithium vibrations and the deformation modes δ(PO3) of the HPO2OH− ion. Assignments are proposed for internal modes of the crystal. Polarized infrared reflection spectra at 293 K and longitudinal Raman spectra at 293 K and 83 K in the 400–2500 cm−1 region are reported for 7LiH2PO3 single crystal. An analysis in terms of Drude oscillators leads to a better understanding of the dielectric properties of the monocrystal and also to the determination of the dispersion parameters of the transverse and longitudinal optical modes. The values obtained for the longitudinal frequencies and for the oscillator strengths in Raman scattering and infrared reflection are in good agreement.
Pollutant trapping studies. 2—Spontaneous and resonance Raman studies of the surface reaction of sulphur dioxide on zeolites
Authors: Tsai Peter , Cooney Ralph P. 
Published: May 2005

AbstractRaman spectra of SO2 adsorbed on zeolites X, Y and A are reported together with a normal coordinate analysis of the various spectra of the adsorbed molecuar SO2. The data indicate that crystal‐like SO2 is adsorbed on cation sites II and III of the zeolitic oxide framework. Internal SO2 force constants quantifying adsorbate distortion are developed and compared with the frequency difference parameter,Δ(ν3–ν1). Raman spectral data also indicate the formation of several decomposition products of SO2, generated by surface reactions, which may include S, S2, S4, SxO, SO and SO. Of these the lines attributed to S, S2, S4 and SxO exhibit resonance enhancement.