bluuebunny/crossref_metadata_2025 huggingface dataset:
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

A 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

The 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

The 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

Model 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

Raman‐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

Model 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

The 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

The 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

The 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

Tellurc 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

A 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

The 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

The 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

The 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.
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

The 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

The 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

The 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

Resonance 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

Carboxylate 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

Raman 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

The 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

Starting 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

The 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

Tetradesmethyl‐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

The 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

The 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

Explicit 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

The 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

The 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

Polarized 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

The 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

The 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

Raman 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

The 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

IR 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

The 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

The 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

Raman 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

Raman 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

The 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

The 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.
Accurate spectroscopic constants of nitrogen determined from stimulated Raman spectra of the fundamental and first hot bands
Authors: Tabyaoui A. , Lavorel B. , Millot G. , Saint‐Loup R. , Chaux R. , Berger H.
Published: May 2005

Nitrogen spectra of the Q‐branch of the fundamental and the first hot bands were recorde with a high‐resolution stimulated Raman spectrometer at atmospheric pressure and ca. 1300 K. The absolute frequencies of the Raman lines were measured with high accuracy, leading to a refinement of spectroscopic constants. A temperature estimation was also performed from the Raman intensities.
Comparison of different phase conjugate and backscattering arrangements in non‐linear Raman spectroscopy
Authors: Pfeiffer M. , Lau A. , Werncke W.
Published: May 2005

A theoretical and experimental comparison of coherent anti‐Stokes Raman scattering (CARS) and Raman‐induced phase conjugation (RIPC) techniques has been carried out. In most cases the RIPC techniques are much more sensitive than CARS to deviations from the phase‐matching conditions, from which it follows that for RIPC much higher accuracy of the alignment and optical homogeneity are necessary. In practice, only one RIPC variant with nearly copropagating pump waves and contrapropagating Stokes waves is applicable to obtain complete spectra. A CARS reflection technique is discussed for the investigation of highly absorbing samples.
Excitation profile study of the resonance CARS spectrum of pyrene in the S1 state for elucidating vibronic coupling
Authors: Akamatsu Naotoshi , Kamisuki Toshio , Adachi Yukio , Hirose Chiaki , Maeda Shiro
Published: May 2005

Resonance CARS excitation profiles of b3g vibrations of pyrene‐h10 and pyrene‐d10 in the lowest excited singlet (S1) state were obtained in the S10, S11 ← S1 transition absorption region. Analysis of the results showed that the vibrational mode at 1433 cm−1 is the major participant in the vibronic coupling between the higher resonant states S10(Ag) and S11(B3g) (B term), while the vibronic coupling of the lower S1(B2u) and S2(B1u) states (C term) makes a significant contribution to the resonance of the mode at 1553 cm−1. The electronic configurations of the higher excited states are discussed on those bases.
High‐precision femtosecond CARS of simple liquids
Authors: Fickenscher M. , Laubereau A.
Published: May 2005

A novel non‐degenerate CARS spectrometer is described with an 80‐fs time resolution, improved measuring accuracy of ca. 1% for the vibrational dephasing time and adjustable frequency positions of the input pulses. Experimental data are reported for CH stretching vibrations of acetone, acetonitrile and bromoform. Negligible inhomogeneous broadening (<4%) is deduced from the observed exponential decay for the vibrational transitions. The effect of orientational motion on the dephasing observations is discussed.
Vibrational studies and molecular motions in tetramethylammonium perchlorate
Authors: Mylrajan M. , Srinivasan T. K. K.
Published: May 2005

Infrared and single‐crystal Raman spectra (20–5000 cm−1) of (CH3)4NClO4 were studied in the temperature range 90–320 K. Low‐temperature vibrational studies at 90 K indicated freezing out of the disorder of the anions with an increased number of molecules.
Polarized Raman and infrared spectra of OH stretching vibrations in the sucrose crystal
Authors: Giermańska J. , Szostak M. M.
Published: May 2005

The bands corresponding to the eight OH stretching vibrations of the sucrose molecule in the crystal were identified using polarized IR and Raman spectra. They were assigned to the individual vibrations on the basis of the dichroic ratio calculations and evaluation of force constants by the Lippincott‐Schroeder model for seven hydrogen‐bonded OH groups. An explanation of the Raman activity of OH vibrations is proposed. A relationship between the anharmonicity of two OH oscillators and the gyrotropy of the crystal is suggested.
Raman and infrared spectra, barriers to internal rotation, vibrational assignments and ab initio calculations on 2‐fluoropropane
Authors: Durig J. R. , Nanaie H. , Guirgis G. A.
Published: May 2005

The Raman (3500‐20 cm−1) and infrared (3500‐50 cm−1) spectra of gaseous and solid 2‐fluoropropane, (CH3)2CFH, the corresponding trideuterated molecule, (CH3)(CD3)CFH, and heptadeuterated species, (CD3)2CFD, were recorded. Additionally, the Raman spectra of the pure liquids were recorded and qualitative depolarization values were obtained. All 27 of the normal vibrational modes were assigned for all three isotopic species based on infrared band contours, depolarization values, isotopic shifts and group frequencies. The vibrational assignment is supported by an ab initio calculation utilizing the 3‐21G basis set to obtain the force constants and potential energy distribution. Additionally, ab initio calculations were carried out utilizing the 6‐31G* basis set to obtain structural parameters and barriers to internal rotation. All of these results are compared with the experimentally determined values and with the corresponding results for some related molecules.
Vibrational spectroscopic study of L‐arginine phosphate monohydrate (LAP), a new organic non‐linear crystal
Authors: Dhanaraj G. , Srinivasan M. R. , Bhat H. L.
Published: May 2005

L‐Arginine phosphate monohydrate (LAP) is a recently discovered organic non‐linear crystal which has the potential to replace a conventional crystal such as potassium dihydrogen phosphate. The polarized Raman and infrared spectra of a single crystal of LAP have been recorded to determine the symmetries of the molecular vibrations. The lattice lines are fairly strong compared with the others and show pronounced intensity variations with the orientation of the crystal. The high‐frequency lines are assigned to the vibrations of the various molecular groups such as NH3+, NH2+, NH2, CH2, CH, COO−, H2O and H2PO4− present in the crystal.
Dinucleotide binding to RNase probed with UV resonance Raman spectroscopy
Authors: Molina Marina , Wang Y. , Purrello R. , Spiro Thomas G.
Published: May 2005

Raman spectra are reported for ribonuclease and its complexes with the dideoxynucleotides dCpdC, dCpdA and dCpdG, using 240–250‐nm excitation to enhance the purine and pyrimidine modes, as well as tyrosine and phenylalanine modes of the protein. Spectral perturbations associated with binding were examined via difference spectroscopy. Consistent with the crystal structure of CpA* bound to RNase, the 3′‐cytidine was inferred to be hydrogen bonded to a protein donor via the N‐3 ring atom, but not via the carbonyl O atom, since the 1526 cm−1 band shifts up on binding, as it does when aqueous CMP is protonated, and the CO stretch shifts from 1655 to 1670 cm−1, an effect attributable to polarization via the N‐3 hydrogen bond. The effect of binding on the spectra of the 5′‐purine rings is limited to intensity changes, an augmentation of the adenine 1578 cm−1 band and a diminution of the guanine 1330 cm−1 band, consistent with only weak interactions with the protein. Binding of dCpdC intensifies the 1615 cm−1 protein band, suggesting environmental changes for tyrosine or phenylalanine residues. No spectral perturbation was observed on mixing RNase with dGpdC or dGpdG, consistent with weak or non‐specific binding of dinucleotides lacking a pyrimidine in the 3′‐position.
Effect of doping on the Raman modes in MgO‐doped lithium niobate crystals
Authors: Hu L. J. , Chang Y. H. , Hu M. L. , Chang M. W. , Tse W. S.
Published: May 2005

Raman spectra of a series of MgO‐doped congruent LiNbO3 crystals were obtained with MgO concentrations up to 30 mol.%. Single crystals were successfully grown and no precipitates were discovered. The intensity, frequency and line width of the Raman phonons were studied as a function of doping percentage. An abrupt change was observed near the composition of 7.5 mol.% of MgO‐doped LiNbO3 crystal. From the spectral changes it is proposed that Mg2+ replaces the mis‐sited Nb5+ cation at Li sites first. When these mis‐sited Nb5+ cations have been completely replaced, the Mg2+ cation then replaces the Li+ cation and creates vacancies at Li+ sites.
Raman scattering investigations of KY3F10
Authors: Mortier M. , Gesland J. Y. , Rousseau M. , Pimenta M. A. , Ladeira L. O. , Da Silva J. C. Machado , Barbosa G. A.
Published: May 2005

Single crystals of the fluoride compound KY3F10 (Oh5) were studied by Raman scattering from 40 to 950 K. Group theory analysis predicts 3A1g + 4Eg + 6F2g Raman‐active modes, but the experimental spectra show two F2g modes missing. Over the whole temperature range the frequency shifts are negligible whereas the line widths show a strong increase with temperature. Both reversible and irreversible line width behaviour are exhibited for different temperature runs, indicating a complex microscopic phenomenon underlying the creation of defects responsible for these line widths and their interaction with the different phonon modes. An approximate activation energy for defect creation of ΔE ≈︁ 0.3 eV can be obtained from the temperature behaviour of the line widths. This activation energy may be connected with the high‐temperature ionic conduction mentioned previously for this crystal.
Raman and infrared spectra of NH4H2(IO3)3 and KH2(IO3)3
Authors: Santha N. , Isaac M. , Nayar V. U. , Keresztury G.
Published: May 2005

Raman and infrared spectra of NH4H2(IO3)3 and KH2(IO3)3 were recorded and analysed. The observed splittings of the stretching modes of IO3− are due to the distortion of the IO6 octahedra. In NH4H2(IO3)3, the ammonium ion can rotate freely and the NH4+ group forms only weak hydrogen bonds with the oxygen atom. Owing to Fermi resonance, three stretching bands are observed for the OH vibration in both compounds. The hydrogen bonds are slightly shorter in KH2(IO3)3 than in NH4H2(IO3)3.
Raman and IR spectra of β‐alanine and sarcosine monophosphates
Authors: Joe I. Hubert , Philip Daizy , Aruldhas G. , Botto I. L.
Published: May 2005

The IR and Raman spectra of the monophosphates of β‐alanine and sarcosine were recorded and analysed. The carboxylic group is found to exist as COO− and the orthophosphate as H3PO4 in β‐alanine monophosphate. In sarcosine monophosphate these groups seem to exist as COOH and H2PO4−, respectively.
Resonance Raman spectral studies on the vibrational frequencies of some azo dyes in the solid state and in alkaline solution
Authors: Chattopadhyay S. , Kastha G. S. , Brahma S. K.
Published: May 2005

Resonance Raman spectra of two azo dyes, 2‐hydroxy‐2′‐carboxy‐5‐methylazobenzene and 2‐hdroxy‐2′‐carboxy‐5‐methoxyazobenzene, in the solid state and in 0.1 M NaOH solution were investigated. For comparison, their infrared absorption spectra were also recorded in the solid state and in solution in chloroform. Characterization of the Bands in the Raman spectra of the alkaline solution and their assignments to different hybridized modes were made on the basis of the deprotonated azo and quinonoid molecular forms (in resonance) in alkaline solution.