bluuebunny/crossref_metadata_2025_split huggingface dataset:
Halogen‐substituted amides. VI—vibrational spectra of some fluoro‐ and iodo‐substituted acetamides
Authors: Murthy E. Krishna , Rao G. Ramana 
Published: May 2005

AbstractThe Raman spectra of 2‐fluoroacetamide, trifluoroacetamide and 2‐iodoacetamide were recorded 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 500–50 cm−1, were also obtained. The frequencies were assigned to various fundamental modes of the molecules on the basis of qualitative considerations.
Raman and infrared studies on (5‐dimethyl‐aminopenta‐2,4‐dienylidene)dimethylammonium perchlorate
Authors: Sano Norimichi , Shimizu Masaaki , Tanaka Jiro , Tasumi Mitsuo 
Published: May 2005

AbstractPre‐resonance Raman and infrared spectra of (5‐dimethylaminopenta‐2, 4‐dienylidene)dimethylammonium per‐chlorate have been measured in various environments. Unusual intensity changes of some particular peaks in the Raman spectra are observed for two crystalline polymorphs and solutions of the dye. Most of the Raman and infrared bands in solution are assigned to normal modes. This analysis allows the major difference between the spectra of two polymorphs to be explained.
Phonon spectra and unit cell analysis of 2‐cyanothiophene
Authors: Cataliotti Rosario Sergio , Antolini Francesco , Morresi Assuntina , Santinelli Fabio , Santini Sergio 
Published: May 2005

AbstractVibrational spectra of 2‐cyanothiophene in the solid state reveal that the crystals are ordered below the freezing point and have an orthorhombic C2v unit cell. Intermolecular forces between the two molecules occupying the Bravais unit are not strong enough to promote the separation of all the Davidov doublets of the phonon states.
Halogen‐substituted amides. VIII—normal coordinate analysis of trifluoroacetamide
Authors: Murthy E. Krishna , Rao G. Ramana 
Published: May 2005

AbstractA 23‐parameter modified valence force field has been employed for a normal coordinate analysis of trifluoroacetamide. A least‐squares technique was used to refine the force constants. The potential energy distributions were also calculated. The nature of the absorption bands is discussed in relation to the mixing of vibrational frequencies.
Resonance Raman spectra of the complex pentacyano‐4‐cyanopyridineferrate(II) and its 4‐cyanopyridine‐bridged binuclear complex with a ruthenium(II) pentaamine unit
Authors: Della Védova C. O. 
Published: May 2005

AbstractComparative resonance Raman effect (RRE) studies of both the 4‐cyanopyridine complex with the pentacyanoferrate(II) anion, the first [Fe(CN)5L]3− anion studied by RRE, and a binuclear complex formed by this anion with 4‐cyanopyridine as bridging ligand and a pentaamineruthenium(II) moiety are reported. The RR spectra obtained show differences in the number of enhanced modes in each case. The spectroscopic data suggest coordination of the Fe(CN)5 unit through the pyridine nitrogen of 4‐cyanopyridine in both the mononuclear and the binuclear complex. Assignment of the electronic spectra as being due to metal to ligand charge transfer (MLCT) (FeII → pyridine‐N, 4‐cyanopyridine) is proposed for the bands at 476 nm (aqueous solution) and 470 nm (solid dispersion in KBr) in both the mononuclear and the binuclear complex, respectively, and MLCT (RuII → nitrile, 4‐cyanopyridine) for the band at 418 nm (solid) observed in the binuclear complex only.Excitation profiles of the 1600 cm−1 bands in the mononuclear complex (in acetonitrile‐methanol solution) and of the 1607, 1207 and 1020 cm−1 bands in the binuclear complex (as solid) were obtained and are interpreted.
Line widths in the pure rotational Raman spectra of nitrogen, oxygen and hydrogen broadened by foreign gases
Authors: Edwards H. G. M. , Long D. A. , Webb S. W. 
Published: May 2005

AbstractBroadening coefficients, σp, have been determined for the pure rotational Raman lines of nitrogen and oxygen, perturbed by hydrogen, helium and methane, and of hydrogen broadened by helium, argon, nitrogen and carbon monoxide, over the pressure range 2–100 bar with a host gas partial pressure of 1 bar. The results are summarized below:magnified imageThe broadening coefficients are discussed in relation to the dipole, quadrupole and octopole moments and the polarizabilities of the perturbing species.
Vibrational dephasing of arsine in the liquid and plastic crystalline states
Authors: Wilde Richard E. 
Published: May 2005

AbstractRaman spectra of the ν1 bands of AsH3 have been obtained for the liquid state and for phase I of the solid state. It is shown that phase I is a plastic crystalline phase. A modeling procedure applied to the vibrational autocorrelation function shows that the modulation of the vibrational frequency is fast and that the vibrational dephasing is probably caused by the rotations. Evidence for a ν1‐ν3 Coriolis‐coupling effect is also presented.
Spectra and structure of small ring compounds. LII—Raman and far‐infrared spectra of solid 1,1‐dicyanocyclopropane and ab initio calculations of cyclopropane, cyanocyclopropane and 1,1‐dicyanocyclopropane
Authors: Little T. S. , Zhao Wenyun , Durig J. R. 
Published: May 2005

AbstractThe Raman (3500–10 cm−1) and far‐infrared (400–70 cm−1) spectra of solid 1,1‐dicyanocyclopropane have been recorded. The molecular structure of cyclopropane, cyanocyclopropane and 1,1‐dicyanocyclopropane have been calculated by ab initio methods at the 4‐31G basis set level. The harmonic force fields for cyanocyclopropane and 1,1‐dicyanocyclopropane have also been calculated using the same basis set. By the combination of experimental data and normal coordinate calculations with scaled ab initio force constants, the vibrational assignments for these two molecules have been revised. Discrepancies between the previously reported and present assignments are discussed. The molecular structures of cyanocyclopropane and 1,1‐dicyanocyclopropane obtained in this work are compared with the molecular structure of cyclopropane.
Study of factors responsible for the half‐width of the NH3 Raman torsional band in crystalline sulphamic acid
Authors: Bocquet J. F. , Abello L. , Muthusubramanian P. , Lucazeau G. 
Published: May 2005

AbstractRaman spectra of single crystals of NH3SO3 were recorded for the B1g and B3g polarization in the range 10–500 cm−1 for the temperature range 10–360 K and for zz, zy and zχ polarizations in the range 2500–3300 cm−1 at 77 and 300 K. Neutron diffraction data on the polycrystalline sample at 4 and 77 K were obtained in order to study the structural variation with temperature. Potential energy calculations made using atom‐atom potentials show that torsional mode broadening is not caused by hot‐band transitions. The ful width at half maximum intensity of the torsional mode was accounted for in terms of the reorientational motion of the NH3 rotor and the pure vibrational dephasing (PVD). At 300 K the reorientational motion contributes about 2 cm−1. The PVD broadening was calculated on the basis of cubic coupling between the torsional and hydrogen bond stretching modes following a semi‐classical model. Its contribution at 300 K was estimated to be 25 cm−1.
Raman and infrared study of reorientational dynamics in trifluorobenzene
Authors: Yuan P. , Chen A. F. T. , Schwartz M. 
Published: May 2005

AbstractThe Raman spectral bandwidths of two A1′ vibrations of 1,3,5‐trifluorobenzene (TFB) were measured in the neat liquid as a function of temperature and in the solvents CH2Cl2 and CS2. The Raman and IR linewidths of two E′ modes were also measured in solution. Derived values of the two rotational diffusion constants, D⊥ and D∥, were compared with the predictions of several current theories. It was observed that the Hynes–Kapral‐Weinberg (HKW) theory is superior to both the microviscosity–free rotor and Hu–Zwanzig ‘slip’ models of reorientational diffusion. Calculated values of D⊥ and D∥ for TFB in solution using the HKW model are in excellent agreement with the experimentally measured diffusion constants.
Fourier transform Raman spectra of deeply coloured inorganic species. I–The permanganate ion
Authors: Hendra P. J. , Le Barazer P. , Crookell A. 
Published: May 2005

AbstractThe literature contains only very poor Raman spectra on several deeply coloured ions. In this paper, new spectra of high quality are given for the permanganate ion, obtained using Fourier transform Raman techniques and nearinfrared excitation. Several other tetraoxo compounds have also been studied by these techniques as a comparison.
Analyse Vibrationnelle et Structurale en Série Aliphatique Saturée. IX—Spectres de Vibration de l'Acide Pimelique et de ses Sels Alcalins en Solution Aqueuse
Authors: Delarbre J. L. , Fabrègue E. , Maury L. , Bardet L. 
Published: May 2005

AbstractThe Raman and infrared spectra of pimelic acid, (CH2)5[COOH (D)]2, and its potassium salts in aqueous solution were recorded from 4000 to 200 cm−1. The two salts belong to the Cs symmetry point group whereas the acid has C1 symmetry. These results are similar to those found previously for lower alkanedloic acids with an odd number of carbon atoms, namely glutaric acid, (CH2)3(COOH)2, and malonic acid, CH2(COOH)2.
Vibrations of the tetrahedral AlCl4− ion in crystals: An estimation of crystal environmental effects on the spectra of the chloroaluminate ion in crystals
Authors: Narayanan V. Anantha 
Published: May 2005

AbstractForce constans for AlCl4− in a series of alkali metal compound crystals were calculated using an orbital valence force field. The calculated force constants were utilized to estimate, by empirical methods, the spreads in AlCl bond lengths and ClAlCl angles caused by crystalline environmental effects. They are of the order of few hundredths of an ångstrom and a few degrees, respectively. These variations are compared and correlated with the structure details available in the literature for these ions in crystals.
A readily assembled triple spectrometer for pulsed laser‐excited Raman scattering with multichannel detection: Resonance Raman spectra in solution of a bridged species, [CuI(4,4′ ‐bipyridyl)(PPh3)2 ClO4]m, and of photogenerated transients in metal carbene complexes, (CO)5WC(OR)R′
Authors: Bell Steven E. J. , Gordon Keith C. , McGarvey John J. 
Published: May 2005

AbstractA simple two‐stage spectrometer for multichannel Raman spectroscopy is described which permits detection by an intensified diode array of Q‐switched laser‐excited Raman scattering at frequencies ≥200 cm−1 from the laser line. It is assembled from a double grating spectrometer operated in subtractive dispersion and coupled to a 0.5 m spectrograph with a 1200 grooves mm−1 grating. Excitation is by means of Q‐switched Nd/YAG laser in tandem with an H2 or CH4 Raman wavelenth‐shifting cell.Raman spectra are reported for two types of metal‐centred system. Solutions in CH2Cl2 or MeOH of a yellow solid (A) formed by reacting the copper (I) salt [Cu(PPh3)4]+[ClO4−] with the ligand 4,4′‐bipyridine (L) exhibit Raman spectra which are dominated by bands in the range 750‐1620 cm−1. The bands are assignable to modes of L enhanced in resonance with a CuI → L charge‐transfer transition. When an excess of PPh3 is added the UV absorption of A shifts to shorter wavelengths and the enhanced modes of L virtually disappear, leaving non‐resonant PPh3 features, consistent with the probe laser lines being off‐resonance with the CuI → L charge‐transfer transition. The findings are consistent with a tentative proposal that A has a chain structure with L as a bridging ligand.Resonance Raman spectra are also reported for solutions in CCl4 of the metal carbene complex (CO)5 WC(OCH3)CH3 at excitation wavelengths of 354.7, 396 and 416 nm. Changes with λexc in the relative intensities of vibrational bands show that the spectra are due to a laser‐generated transient, possibly a solventcoordinated fragment, (CO)4W[S]C(OCH3)CH3, formed following CO photodissociation. Studies using increasing beam focus at 416 nm suggest that solvent substitution at the metal centre causes only minor changes in the vibrational spectrum. Preliminary low‐frequency spectra for a laser‐generated transient in the analogous complex (CO)5WC(OCH3)Ph are described.
Spectra and structure of organophosphorus compounds. XXXV—Raman and infrared spectra, conformational stability, and ab initio calculations of trivinylphosphine
Authors: Durig J. R. , Zhao Wenyun , Little T. S. 
Published: May 2005

AbstractThe Raman spectra (3600 to 10 cm−1) of gaseous, liquid and solid and the infrared spectra (3600 to 30 cm−1) of gaseous and solid trivinylphosphine, P(CHCH2)3, have been recorded. Additonally, qualitative depolarization ratios of the Raman lines for the liquid have been obtained. From these data it is concluded that at least two and possibly as many as four conformers are present in the fluid phases; however, it has not been possible to identify specific spectral bands to individual conformers. An ab initio Hartree–Fock gradient calculation employing the 3–21G* basis set was carried out and the results indicate that there are four different conformers of low energy, i.e. with an energy difference of less than 2 kcal mol−1 among them. A complete vibrational assignment is proposed based on depolarization values, infrared band contours and group frequencies. The number of lattice modes in the Raman spectrum of the solid indicate that there are at least two molecules per primitive cell. The results of this study are compared with the corresponding data for some similar molecules.
Laser Raman and infrared spectra of silylgermane and its vibrational analysis
Authors: Mohan S. , Prabakaran A. R. , Payami Feridoun 
Published: May 2005

AbstractThe laser Raman and infrared spectra of silylgermane were recorded on a Cary Model 82 grating spectrophotometer with an argon laser source and on a Perkin‐Elmer 983 double‐beam grating spectrophotometer, respectively. The spectra were analysed on the basis of fundamentals, combinations and overtones and the frequencies were assigned to various modes of vibration, assuming C3ν point group symmetry. Further, based on the present assignments, a complete vibrational analysis was carried out for this molecule and the results are briefly discussed.
Modelling of absorption and non‐linear vibronic spectra of polyatomic molecules
Authors: Kircheva P. P. , Pfeiffer M. , Lau A. , Werncke W. 
Published: May 2005

AbstractModel calculations of the absorption and the four quantities representing third‐order non‐linear susceptibility [the real and imaginary part of the excitation profile and of the resonance background component for resonance coherent anti‐Stokes Raman scattering (CARS), R, J, b′ and b″, respectively] were carried out for polyatomic molecules. Comparison with previously acquired experimental data for bisdimethylaminoheptamethine perchlorate shows satisfactory agreement, except for b′ and b″. Some molecular parameters (the shift parameter of the active vibrations and the vibronic relaxation constant) were estimated. It is concluded that the resonance background is more sensitive to the model than the absorption and the excitation profile.
Raman‐induced kerr effect spectroscopy of solutions
Authors: Borysow Jacek , Taylor Roger H. , Keto J. W. 
Published: May 2005

AbstractRaman‐induced Kerr effect spectroscopy (RIKES) as a tool for the investigation of species in solution is presented. RIKES has proved to be a particularly useful probe for Raman modes of molecules in solution because control of the polarizations of the interacting laser fields allows non‐resonant solvent contributions to the background to be minimized. New techniques to subtract laser power fluctuations from the signal have further increased the sensitivity of RIKES. Spectra of carbon tetrachloride, benzene and the hydroxide ion are presented to show the utility of RIKES for investigating solutions. The ability to decrease background noise by controlling the polarization of the pump laser was demonstrated by studying the 459 cm−1 carbon tetrachloride resonance. Concentration studies on benzene in carbon tetrachloride showed a narrowing of the 992 cm−1 mode of benzene as its concentration was decreased. The sensitivity of the technique is demonstrated with spectra recorded on 0.01 M benzene in carbon tetrachloride. The 3620 cm−1 OH− resonance is presented for a 10 M solution of NaOH in water. A nearby water resonance makes the OH− mode difficult to see at lower concentrations. Polarization tuning was not able to improve the RIKES sensitivity in this case.
Refined analysis of Raman excitation profiles for cis‐(CH)x and ‐(CD)x polymers
Authors: Tarr Allan W. , Siebrand Willem 
Published: May 2005

AbstractModel calculations are reported aimed at interpreting the Raman excitation profiles observed by Lichtmann et al. They refine earlier calculations by Siebrand and Zgierski based on displaced harmonic oscillators. A distribution of conjugation lengths is introduced and the dependence of the model parameters, in particular the resonant state energy, on this length is investigated. This, together with an allowance for vibrational frequency changes and non‐Condon effects, yields a much improved fit to the observed profiles. The results suggest a narrow distribution of relatively short conjugation lengths (⩽20 double bonds), contrary to most earlier reported distributions based on the dispersion of Raman bands, but comparable to a distribution based on isomerization kinetics.
Normal modes calculation for benzene in a local symmetry force field
Authors: Hamdache F. , Vergoten G. , Lagant P. , Benosman A. 
Published: May 2005

AbstractThe GF matrix method has been applied to the analysis of the aromatic ring and the benzene molecule. A normal coordinate treatment based on the local symmetry force field was performed. A set of the elements of the F matrix was obtained that gives vibrational frequencies of these molecules in agreement with the observed values.
Raman polarizabilities of the ν1, ν4 bands of methyl iodide
Authors: Santos J. , García Hernández M. 
Published: May 2005

AbstractThe Raman spectrum of methyl iodide was recorded in the 3000 cm−1 region with a resolution of 0.25 cm−1. The range measured includes the ν1, ν4 bands of symmetry species A1 and E, respectively. Using published vibrational–rotational constants, a computer simulation of the band contour was carried out, yielding relative values of Raman polarizability derivatives for these bands. Further, from previous measurements of the scattering cross‐section the moduli of the Raman tensor components related to ν1 and ν4 vibrational modes were determined.
Raman and infrared spectra, conformational stability and Ab initio calculations for n‐propylamine
Authors: Durig J. R. , Beshir Wafaa B. , Godbey S. E. , Hizer T. J. 
Published: May 2005

AbstractThe Raman (3500–10 cm−1) and infrared (3500–50 cm−1) spectra of gaseous and solid n‐propylamine, CH3CH2CH2NH2, and its deuterated analog, CH3CH2CH2ND2, were recorded. Additionally, the Raman spectra of the liquids were measured and qualitative depolarization values were obtained. From the fact that several distinct Raman lines disappear on goning from the fluid phases to the solid state, it is concluded that the molecule exists as a mixture of several conformers, with the trans–trans conformer being the most stable form in the solid. The first term indicates the position of the methyl group relative to the CN bond, whereas the second term indicates the position of the lone electron pair on the nitrogen relative to the central CC bond. Relying mainly on group frequencies, depolarization data and relative intensities of Raman and infrared bands, a complete vibrational assignment is proposed for the trans–trans conformer. Ab initio calculations were carried out on these molecules, employing both 3–21G and 6–31G* basis sets. The results obtained using these basis sets are compared, and used in normal coordinate calculations. The results of the ab initio calculations support the vibrational assignment, and also indicate that it is the trans–trans and trans–gauche conformers which are the more stable forms of n–propylamine and have nearly equal energies.
Vibrational spectroscopic studies of phase transition in ferroelectric TAAP
Authors: Shashikala M. N. , Raghunatha Chary B. , Bhat H. L. , Narayanan P. S. 
Published: May 2005

AbstractTellurc acid ammonium phosphate (TAAP) is a new class m ferroelectric with a transition temperature of 45°C. Structural data and preliminary spectroscopic studies confirmed the presence of NH…O hydrogen bonds. Raman spectroscopic studies on this crystal were carried out in the temperature range 20–80 °C to look for possible spectral changes as a result of phase transition. A detailed analysis of the line width and frequencies was carried out across the phase transition in order to understand the nature of the phase transition. From the spectral features of the bands in different regions it is inferred that the groups TeO6, PO4 and NH4 do not undergo changes that could trigger the phase transition. On the other hand, the broadening of the bands in the range 2600–3400 cm−1 suggests the possibility of an order–disorder type of transition phenomenon involving hydrogen bonds. This is further supported by the shift of the transition temperature from 45 to 87°C on deuteration.
Halogen‐substituted amides. IX—Normal coordinate analysis of out‐of‐plane vibrations of some fluoro‐ and iodo‐substituted acetamides
Authors: Krishna Murthy E. , Ramana Rao G. 
Published: May 2005

AbstractA symmetrized valence force field was employed for a normal coordinate analysis of the out‐of‐plane vibrations of 2‐fluoroacetamide, 2‐iodoacetamide and trifluoroacetamide. The force constants were refined using an Overlay least‐squares technique for 2‐fluoroacetamide and 2‐iodoacetamide. The potential energy distributions were calculated and unambiguous vibrational assignments made.
Study of the fermi doublet ν1‐2ν2 in the Raman spectrum of liquid carbon disulphide by the solvent variation method and the modified winther method
Authors: Bertran José Fernández , La Serna Boris 
Published: May 2005

AbstractThe Fermi doublet ν1–2ν2 in the Raman spectrum of liquid CS2 at 22 °C and in the pressure range 1 bar–10 kbar was studied by the solvent variation method and the modified Winther method. The values of the parameters W122 and K122 are discussed and compared with values reported in the literature.
Resonance Raman study of the structures of trans and cis isomers and the CC stretching frequencies of N,N′‐derivatives of indigo
Authors: Itoh Shinichi , Ohno Shinji , Hasegawa Nobuhiro , Takahashi Hiroaki 
Published: May 2005

AbstractThe CC stretching frequencies of N,N′‐derivatives of indigo reveal that although these compounds, with the exception of N,N′‐oxalylindigo, are considerably twisted about the central CC bond owing to steric repulsion, the deviation from the coplanarity of the two halves of the molecule is not very different between the trans and cis isomers: the cis isomers are not always more twisted than the corresponding trans isomers. In contrast to the commonly accepted interpretation, the large hypsochromic shifts brought about by the trans → cis isomerization of N,N′‐derivatives of indigo cannot be explained as being due to a departure from coplanarity in the cis configuration.
Raman and infrared spectra of 2‐amino‐6‐nitrobenzothiazole, normal coordinate analysis and vibrational assignments
Authors: Mohan S. , Prabakaran A. R. , Payami Feridoun 
Published: May 2005

AbstractThe infrared and Raman spectra of 2‐amino‐6‐nitrobenzothiazole were recorded. The observed frequencies were assigned to different modes of vibrations on the basis of normal coordinate calculations assuming Cs point group symmetry.