bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman and infrared spectra, normal coordinate calculations and vibrational assignment for 1,1,1,3,3,3‐hexafluoro‐2‐propanimine
Authors: Durig J. R. , Lindsay N. E. , Sheehan T. G. 
Published: May 2005

AbstractThe Raman (4000–10 cm−1) and infrared (4000–50 cm−1) spectra of gaseous and solid 1,1,1,3,3,3‐hexafluoro‐2‐propanimine, (CF3)2 CNH, were recorded. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. A complete vibrational assignment for the normal modes utilizing Cs symmetry is proposed based on band contours, depolarization values and group frequencies. The assignment is supported by a normal coordinate calculation utilizing a modified valence force field to calculate the frequencies and potential energy distribution of the normal modes. A CF3 torsional mode was observed in the Raman spectrum of the liquid at approximately 60 cm−1, from which a periodic barrier of 5.0 kcal mol−1 (1 kcal = 4.184 kJ) was calculated. The results are compared with similar data for some corresponding molecules.
Vibronic couplings in vibrational spectra of the non‐centrosymmetric 2‐naphthol crystal. Comparative study of IR, Raman and inelastic incoherent neutron scattering spectra
Authors: Szostak M. M. , Natkaniec I. 
Published: May 2005

AbstractThe polarized IR and Raman spectra of 2‐naphthol as a single crystal, in solution and as a KBr pellet or powder, and the inelastic incoherent neutron scattering spectra of the powder were measured and compared with the corrresponding naphthalene spectra. The previous assignments of fundamental vibrations were confirmed, except for the in‐plane and out‐of‐plane OH bending modes in the crystal. The medium‐dependent relative intensities and frequencies of the vibrational bands are interpreted in terms of the competition between an intramolecular charge transfer interacting with vibrations (vibronic coupling) and hydrogen bonding.
Raman and far‐infrared study of crystalline 1,1,1‐trichloroethane and 1,1,1‐trichloroethane‐d3
Authors: Prystupa D. A. , Anderson A. , Torrie B. H. 
Published: May 2005

AbstractThe lattice vibrations of the low‐temperature phase of CH3CCl3 and CD3CCl3 have been observed by Raman and far‐infrared techniques. The results are compared with the predictions of group theory, and the peaks are assigned on the basic of their frequency shifts on deuteration. Low‐temperature Raman and far‐infrared spectra of the internal modes are also presented.
Resonance Raman excitation profile of cobalt phthalocyanine at room temperature and 10 K
Authors: Bartholomew C. R. , McConnell A. A. , Smith W. E. 
Published: May 2005

AbstractResonance excitation profiles have been obtained for cobalt phthalecyanine at both room temperature and 10 K using a compressed disc of silver and the phthalocyanine. Low‐frequency vibrations are shown to be influenced mainly by displacements on the bonding nitrogen, but high‐frequency vibrations show a more complex pattern with some evidence that the vibrations v3 and v28 depend on Cα displacements. By comparison with copper, there appears to be a greater degree of scattering from 0–0 and 0–1 transitions and there is a shift towards increase 0–0 scattering in the sharper low‐temperature profiles. It is concluded that a distortion, dynamic at room temperature and static at low temperature, plays a key role in determining the relative scattering and this distortion is larger for copper phthalocyanine than for cobalt phthalocyanine.
Ultraviolet resonance Raman enhancement of the carboxylate and guanidinium groups in amino acids
Authors: Hildebrandt Peter , Czernuszewicz Roman S. , Grygon Christine A. , Spiro Thomas G. 
Published: May 2005

AbstractCarboxylate and guanidinium groups of amino acids have been studied by ultraviolet resonance Raman (UVRR) spectroscopy. On near‐resonant excitation (192 nm) into the allowed π–π* transition of the carboxylate chromophore, the vibrational spectrum of aspartate displays only one band originating from the COO− symmetric stretching mode, consistent with an A‐term enhancement mechanism. The UVRR spectra of the guanidinium ion reveals a complex vibrational pattern, and the bands have been assigned with the aid of a normal coordinate analysis. UV enhancement is observed for both asymmetric (E′) and totally symmetric (A1′) modes, and also for the overtone of the out‐of‐plane CN3 bending mode, Γ(A2″). The E′ enhancement is suggested to reflect Jahn—Teller splitting in the first allowed electronic transition A2″ ← E″, whereas the 2Γ(A2″) enhancement requires a lowering of the force constant for out‐of‐plane bending in the excited state, consistent with its expected tendency toward pyramidalization. Similar enhancement patterns are seen in the UVRR spectra of the guanidinium chromophore in methylguanidinium and arginine, which show, in addition, splittings and intensity redistribution due to the substituents. The excitation profiles of guanidinium and arginine reveal a complex structure that may arise from an excited‐state Jahn—Teller effect. The Raman enhancements are too low to permit detection of guanidinium or carboxylate in the UVRR spectra of proteins, even at wavelengths as low as 192 nm.
The Raman spectrum of ammonium metavanadate
Authors: Park Y. S. , Shurvell H. F. 
Published: May 2005

AbstractRaman spectra of polycrystalline NH4VO3 and ND4VO3 were recorded at various temperatures. Splittings were observed for most fundamentals and the external mode region contains at least eleven bands. The spectra are interpreted in terms of a group theoretical analysis based on the molecular symmetry and the known crystal structure.Wavenumber vs temperature curves for several internal and external modes show minor anomalies near 150 K, which might be due to an order–disorder phase transition. The bands assigned to ammonium ion librations are observed at room temperature, which implies that the onset of ‘free’ rotation of the NH4+ ion (on the vibrational time scale) occurs at a much higher temperature in NH4VO3 than it does in other ammonium salts.
Further assessment of reduction procedures for Raman spectra
Authors: Murphy W. F. , Brooker M. H. , Nielsen O. Faurskov , Praestgaard E. , Bertie John E. 
Published: May 2005

AbstractThe origin of reduction procedures used to transform (or normalize) relative Raman intensities is reviewed and discussed in detail in order to clarify the difference between an approach based on the frequency domain representation of Placzek and that based on the time domain representation of Heisenberg as developed by Gordon. These procedures are not designed to replace standard methods for the measurement of accurate absolute Raman scattered intensity. However, they do provide a practical method for a first‐order comparison of Raman spectra for samples measured under different conditions of phase, concentration and temperature and for samples measured with different excitation frequencies. Especially for the low‐wavenumber region, reduced spectra allow analyses of significant spectral features: a linear baseline may be more easily defined, which in turn permits easier measurement of peak maxima, band shapes and relative intensities. Further, certain forms of the reduced Raman spectrum may be compared directly with the corresponding infrared absorption spectrum.
Preparation and properties of fluorocarbonylsulphenyl bromide, FC(O) SBr
Authors: Della Védova C. O. 
Published: May 2005

AbstractStarting from trimethylsilyl bromide and fluorocarbonylsulphenyl chloride, the compound fluorocarbonylsulphenyl bromide, FC(O)SBr, has been prepared. The IR, Raman, UV, mass, 19F‐ and 13C‐NMR spectra have been obtained and interpreted. The vibrational data point to the existence of planar trans and cis conformers (with respect to the halogens), the trans conformer being by far the more abundant at room temperature. For the trans conformer an approximate force field has been calculated for the A′ modes. General results agree with reports for other carbonylic FC(O)SX compounds.
Improved polarizability tensor derivative for the ν2 mode of hydrogen sulphide
Authors: Bouachir M. , Perrot M. , Lascombe J. , Bribes J.‐L. , Gaufrés R. 
Published: May 2005

AbstractThe polarized rovibrational Raman spectra of the ν2 band of hydrogen sulphide in the gaseous phase, at a pressure of 2 atm, were recorded in order to redetermine the relative components of the polarizability tensor derivative associated with the Q2 normal coordinate of this molecule. For the computation of the rovibrational levels entering the simulation of the depolarized spectrum, a Watson's A‐reduced hamiltonian was used. A determination of the Rba ratio of the components of the tensor more accurate than that of previous workers was possible. The results are discussed and compared with the bond polarizability theory predictions.
Resonance Raman studies on tetradesmethyl‐β‐carotene aggregates
Authors: Okamoto Hiromi , Hamaguchi Hiro‐O , Tasumi Mitsuo 
Published: May 2005

AbstractTetradesmethyl‐β‐carotene is found to form aggregates in a mixed solvent of methylcyclohexane and isopentane at temperatures below 180 K. The absorption band around 470 nm (0–0 transition) of the monomer splits into a pair of absorptions (exciton bands) on aggregation, one around 400 nm and the other around 500 nm. Four Raman bands are observed at about 1520 (ν1), 1130 (ν2), 1600 (νa) and 1570 (νb) cm−1 for the aggregate, two of them (ν1 and ν2) being observed with strong intensities also in the Raman spectrum of the monomer. The ν1 and ν2 bands are observed with exciting radiation in resonance with either one of the two absorptions of the aggregate, whereas the intensities of the other two Raman bands (νa and νb) are enhanced only in resonance with the absorption around 400 nm. These results are discussed in terms of vibronic coupling involving a forbidden singlet state in the near‐ultraviolet region.
Spectra and structure of small ring compounds. Part LV–Conformational stability of bromocyclobutane from Raman and far‐infrared spectra of the gas
Authors: Durig J. R. , Little T. S. , Lee Min Joo 
Published: May 2005

AbstractThe Raman (3200 to 10 cm−1) and far‐infrared (375 to 80 cm−1) spectra of gaseous bromocyclobutane, c‐C4H7Br, have been recorded. A series of Q‐branches observed in both of these spectra, beginning at 149 cm−1 with successive transitions falling to lower frequencies, have been assigned to the ring‐puckering vibrations of both the low‐energy equatorial and high‐energy axial conformers. These data have been fit to an asymmetric potential function of the form V(cm−1) = (6.58 ± 0.21) × 105X4 − (3.27 ± 0.04) × 104X2 × (4.59 ± 0.19) × 104X3 with a reduced mass of 214 amu. Utilizing this potential, the difference between the puckering angles for the two conformers is calculated to be 6°, with the equatorial conformer having the larger value of 20°. Also from this potential function, the energy difference between the equatorial and axial forms is found to be 361 ± 20 cm−1 (1.03 kcal mol−1), with a barrier of 636 ± 20 cm−1 (1.82 kcal mol−1) to interconversion. Experimental values for the enthalpy difference between the two conformers have been determined for both the liquid (297 ± 27 cm−1) and gas (∼ 350 cm−1) from relative intensities of a pair of Raman lines over 90 and 58 °C temperature ranges respectively. These results are compared to the corresponding quantities for some similar molecules.
Line‐scanned micro Raman spectroscopy using a cooled CCD imaging detector
Authors: Bowden Michael , Gardiner Derek J. , Rice Graham , Gerrard Don L. 
Published: May 2005

AbstractThe design of a line‐scanned micro Raman spectrometer is described which uses a cooled, slow‐scan, chargecoupled device imaging detector to obtain sequences of Raman spectra from a ca. 100‐μm long line on a sample. The prototype design has a spatial resolution of <10 μm and a spectral resolution of 4 cm−1. Applications of the instrument to the analysis of mixed TiO2 powders and the components of a zircon mineral are reported.
Raman tensors for AB3C molecules
Authors: Nikiel L. , Wrzalik R. , Bródka A. 
Published: May 2005

AbstractExplicit expressions for the Raman tensor of AB3C molecules are reported in terms of the bond polarizability parameters. By considering Fermi resonance between the ν1, 2ν5 and 2ν2 modes of CH3Cl, CH3Cl, CH3Br, CH3I and CH3F molecules, the relationships between the mean values of the polarizability derivatives with respect to dimensionless normal coordinates of these modes have been found.
Enhancement of sensitivity in high‐resolution stimulated Raman spectroscopy of gases: Applicaion to the 2ν2 (1285 cm−1) band of CO2
Authors: Saint‐Loup R. , Lavorel B. , Millot G. , Wenger C. , Berger H. 
Published: May 2005

AbstractThe application of a multiple‐pass gas cell to quasi‐cw stimulated Raman scattering is demonstrated to be a powerful method for significantly increasing the sensitivity. As a consequence, such a device offers the possibility of working in the 0.1–1 Torr pressure range for weak bands. As a striking example, experimental results are given for the 2ν2 band of CO2 at 1285 cm−1. The band is almost completely resolved with a very good signal‐to‐noise ratio. The Raman frequencies and the collisional broadening coefficients are determined as a function of quantum number J. Moreover, the possibility of auto‐stimulated Raman effect on CO2 at moderate pressure via the sharp ν1 band (1388 cm−1) is demonstrated. The first Stokes signal has been measured with a very narrow line width.
Raman spectra of tetramethylammonium–trimethylammonium mixed ion vermiculite clay intercalation compounds
Authors: Solin S. A. , Jiang H. X. , Kim H. , Pinnavaia T. J. 
Published: May 2005

AbstractThe composition dependence of the Raman spectra of the mixed ion vermiculites [(CH3)4N+]1‐x [(CH3)3NH+]x‐V (V = vermiculite) have been studied in the range 0 ⩽ x ⩽ 1. The torsional mode frequencies exhibit a small shift (ca. 2 cm−1) to lower energy with increasing x and their composition dependence is distinct from that shown by the corresponding modes of Cs1‐xRbx‐V. These differences are attributed to a variation of the guest‐host force constants and in particular to the interactions between the guest ions and the basal oxygens, which depend strongly on the size difference,ΔD, between the guest ion pairs. Using a van der Waals‐type force model and the nearest neighbor approximation, the torsional mode frequencies of the pure end‐member compounds of the two mixed ion systems discussed above have been successfully accounted for.
Infrared and Raman spectra of benzimidazole
Authors: Suwaiyan A. , Zwarich R. , Baig N. 
Published: May 2005

AbstractPolarized IR spectra of partially oriented benzimidazole crystals grown from the melt pressed between salt plates were recorded. The depolarization ratios of the Raman bands in the melt and polarized Raman spectra of a single crystal in all possible orientations were measured. The experimental assignment of the fundamental vibrational bands is compared with a set of calculated values.
Classification of symmetry species of Raman modes of molecular units having different point group symmetries adsorbed on metal surfaces: Symmetry of pyrazine on Ag(111) and Ag(110) surfaces
Authors: Bhattacharjee R. 
Published: May 2005

AbstractThe symmetry species of Raman modes of molecular units belonging to all important and frequently encountered symmetry point groups adbsorbed on metal surfaces are classified into AI, AII, AIII, DIAI(μ), DIAII(μ), etc., and tabulated (DIA = distortion‐induced activity). An example of symmetry species classification of D2h symmetry is discussed. In another example, the Raman spectra of the pyrazine molecule adsorbed on silver surfaces, viz. (111) and (110), are discussed in order to demonstrate the importance of the classification in the study of surface Raman spectroscopy. It is concluded that this molecule attains a polar type of distortion of C1 symmetry on these surfaces.
Effects of inhomogeneous environmental Gaussian broadening on the resonance Raman excitation profiles of tetradesmethyl‐β‐carotene
Authors: Zakaraya Merab G. 
Published: May 2005

AbstractThe effect of static inhomogeneous environmental broadening of resonance Raman excitation profiles was investigated. The roles of diagonal and non‐diagonal terms in the two‐fold sum over the local mode vibrational states in the excited intermediate electronic state are discussed. The theoretical considerations are illustrated by an analysis of published experimental data for tetradesmethyl‐β‐carotene in isopentane solution.
Excited‐state electronic Raman scattering of alexandrite
Authors: Hui Wang , Li‐Ren Lou , Chao‐Shu Shi 
Published: May 2005

AbstractRaman scattering is used to investigate the electronic excited‐states of alexandrite at low temperature (13 K). The Raman spectra of Cr3+ ions in two non‐equivalent types of crystal field sites, one having mirror symmetry Cs the other having inversion symmetry C1, are reported. With λe = 514.5 nm excitation, the Raman transitions of the metastable state 2A′ (Rm1) → 2A″(Rm2) and 2A′(Rm1) → 2A″(2T1) of Cr3+ in the Cs site are 36 cm−1 and 600 cm−1, respectively; with λe = 488.0 nm excitation, the Raman transition between 2Ag(R11) and 2Ag(R12) of Cr3+ in the C1 site is 116 cm−1.
Intra‐ and inter‐molecular interactions in non‐centrosymmetric and centrosymmetric phases of crystalline m‐nitrophenol as studied by polarized Raman and IR spectra. Comparison with internal vibrational spectra of m‐nitroaniline, m‐aminophenol and α‐resorcinol
Authors: Giermańska J. , Wójcik G. , Szostak M. M. 
Published: May 2005

AbstractThe polarized Raman and IR spectra of m‐nitrophenol (mNPh) crystals in two modifications and of mNPh and its deuterated analogue powders in a KBr pellet, nujol mull and CCl4 solution have been measured in the region 200–4000 cm−1. The results are discussed and compared with earlier published data for α‐resorcinol, m‐nitroaniline and m‐aminophenol (mAPh). For the last compound new results, i.e. the IR spectra of the deuterated analogue, are presented, and reinterpretation of some previous assignments is proposed. The assignments of the bands in the mNPh spectra and the re‐examination of the mAPh spectra were facilitated by ordering the spectra of the four compounds into two classes exhibiting common features.It has been found that the differences between the spectra of two phases of the mNPh crystal are small and reflect the differences in interactions between the chains of molecules linked by hydrogen bonds. These interactions perturb particularly the NO2 group vibrations which cannot be treated using the oriented gas model. On the basis of INDO/CI calculations of electronic absorption spectra vibronic couplings in the IR and Raman spectra of the mNPh crystals have been proposed to account for many intensity enhancements.
IR and polarized Raman spectra of Na4P2O7 · 10H2O
Authors: Philip Daizy , George Bini Lizbeth , Aruldhas G. 
Published: May 2005

AbstractIR and polarized Raman Spectra of Na4P2O7 · 10H2O were recorded and analysed. From the spectra it is inferred that the P2O ion has C2ν symmetry in the crystal. The δPOP band is found to belong to the A2 species. Multiple bands observed for the stretching and bending modes of water are probably due to hydrogen bonds of different strengths and the correlation field effect.
Frequencies of HOH, HOD and DOD bending fundamentals in liquid water
Authors: Falk Michael 
Published: May 2005

AbstractThe bending fundamentals ν2 of the three isotopic species of water, H2O, D2O and HDO, were examined in the infrared spectra of liquid water at 0–99.9% D. The peak positions of the three bands vary linearly with the molar fractions of the three isotopic species. The half‐widths of ν2 of H2O surrounded by D2O and of D2O surrounded by H2O, which are largely free from vibrational coupling, have been whown to reflect the distrbution of instantaneous hydrogen‐bond strengths in liquid water. The contribution to the ν2 band width from dynamic processes is relatively small. Vibrational coupling, in the spectra of isotopically pure H2O or D2O, leads to additional broadening and to a sizable shift of the band center to lower frequencies. Small band shifts confirm that weak vibrational coupling also occurs between HDO and H2O and H2O and between HDO and D2O.
Vibrational spectra and conformational behavior of cyclohexylphosphine
Authors: Pai Tain‐Hen , Kalasinsky V. F. 
Published: May 2005

AbstractThe Raman spectra (4000–100 cm−1) of liquid and solid cyclohexylphosphine were recorded, together with the infrared spectra (4000–400 cm−1) of the vapor and solid. Both the Raman and infrared spectra indicate the existence of axial conformers, presumably with gauche and trans orientations of the PH2 group, in addition to the more stable equatorial form. The likelihood of the existence of two equatorial forms of cyclohexylphosphine is discussed, although such a result has not been confirmed experimentally. Variable‐temperature experiments monitoring the very weak Raman lines for the axial conformers give enthalpy differences in the range 1.6–1.8 kcal mol−1· A complete set of vibrational assignments is proposed based on data from the PD2 species and analogy with related substituted cyclohexanes.
Surface‐enhanced Raman spectroscopy of 1,5‐dimethylcytosine on silver and copper sols
Authors: Sánchez‐Cortés S. , García‐Ramos J. V. 
Published: May 2005

AbstractRaman spectra of 1.5‐dimethylcytosine (DMC) as the solid and in aqueous solution are reported. A tentative assignment of Raman bands is made. Surface‐enhanced Raman spectra obtained on silver and on copper colloids show appreciable differences from the normal unenhanced Raman spectra. The geometry of DMC–metal interactions is discussed.
Raman and infrared spectra of the solid chlorofluorocarbons. I—chlorotrifluoromethane
Authors: LeBlanc L. M. , Anderson A. 
Published: May 2005

AbstractRaman and infrared spectra of solid chlorotrifluoromethane have been recorded in both the internal and lattice mode regions at temperatures between 20 K and its melting point. The spectra are compared to the predictions of a group theoretical analysis based on the known molecular and unit cell symmetries. The absence of a centre of inversion is confirmed. Plausible assignments of all main spectroscopic features are presented.
An observation of resonance Raman in the near‐infrared
Authors: Bennett R. , Cutler D. J. , Mould H. M. , Chapman D. 
Published: May 2005

AbstractThe NIR FT Raman spectrum of bacteriorhodopsin is reported. By comparison with previously published spectra it appears that there is some degree of resonance enhancement. Also reported is the spectrum of a sample of blue dyed cotton. Resonance enhancement is proposed to explain strong features in the spectrum not present in either undyed or red dyed material.
Raman intensities near second‐order transitions. Part II‐tris‐(sarcosine)calcium chloride
Authors: Chen Ting , Scott J. F. 
Published: May 2005

AbstractThe theory of light‐scattering intensities originally discussed by Fleury and developed recently by the present authors for LaP5O14 was applied to the second‐order ferroelectric phase transition in tris(sarcosine)calcium chloride, (CH3NHCH2COOH)3CaCl2· It was found that the combination of critical exponents 2β‐γ′ = +0.05 ± 0.002; this is in good agreement with mean field theory, which predicts exactly zero, and sets strict limits on the intensity (small) of any dynamic central mode near the Curie temperature Tc. To′, the transition temperature extrapolated from soft‐mode frequency squared vs. temperature, was found to be 131.5 ± 0.1 K, about 1 K above Tc, demonstrating weak acousto‐optic coupling.