bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of lasers on experimental and theoretical studies of second order Raman spectra
Authors: Hardy J. R. , Karo A. M. 
Published: May 2005

AbstractThe history of experimental and theoretical studies of second order Raman spectra is illustrated by studies that have been made on sodium chloride. It is shown how the introduction of polarized laser sources radically transformed the experimental situation by demonstrating that the observed spectra are highly sensitive to scattering geometry and drastically different from previous results obtained using unpolarized mercury are sources. This necessitates abandonment of previous interpretations of these spectra as simple maps of the two‐phonon joint density of states. Results are presented which show how the inclusion of the Raman polarizability in the scattering calculations, using a simple phenomenological model, also dramatically alters the predicted spectra. Moreover, it does so in such a way as to produce the same degree of agreement between theory and experiment as existed between the earlier spectra and the joint density of states. A short overview of attempts to refine the theory further is presented. It is concluded that subsequent extensions of phenomenological and semi‐phenomenological theories, amied at producing a precise fit to the observed spectra, are not satisfactory. It is therefore argued that attempts be made in the future to derive the Raman polarizabilities from first principles.
Normal mode determination in crystals
Authors: Rousseau D. L. , Bauman R. P. , Porto S. P. S. 
Published: May 2005

AbstractThe group theoretical methods by which the symmetries of normal modes in crystals may be determined are outlined, and a series of tables are presented to facilitate rapid determination of the selection rules for vibrational transitions. Emphasis is placed on the method of nuclear site group analysis in which the number of infrared and Raman active modes of each symmetry may be obtained without detailed analysis of the symmetry elements in the crystallographic unit cell or the construction of tables. By using the tables presented here for most cases identification of the crystallographic space group is sufficient information to allow determination of the vibrational mode selection rules by inspection. Several examples are included in which crystals are analyzed by each of the methods.
Raman intensity de‐enhancement in nontotally symmetric vibrations of copper(II) acetate by forbidden ligand‐field transitions
Authors: Schick G. Alan , Bocian David F. 
Published: May 2005

AbstractThe Raman spectrum of the binuclear transition metal complex copper(II) acetate monohydrate is examined with various excitation wavelengths in the spectral range 17 500 to 25 000 cm−1. Nontotally symmetric vibrations are predominant in the Raman spectrum, and the depolarized Raman bands observed at 320 and 948 cm−1 exhibit marked intensity de‐enhancement as the excitation wavelength approaches the dimer‐associated, Laporte‐forbidden ligand‐field transition at 26 500 cm−1. The intensity de‐enhancement observed for the nontotally symmetric vibrations of copper(II) acetate is in contrast to that observed for other centrosymmetric transition metal complexes studied thus far in which only the totally symmetric vibrations exhibit antiresonance effects. The excitation profiles are calculated for the Raman bands of copper(II) acetate using a model in which the scattering intensity arises from two terms Iα|Be+Bf|2, where Bf couples two charge‐transfer states at 35 000 and 40 000 cm−1 respectively, and Be couples the ligand‐field state to the charge‐transfer state at 35 000 cm−1. The calculated profiles are in good agreement with those observed and predict that the system origin for the ligand‐field transition is located near 21 000 cm−1.
Raman spectra of gases: 23‐Trichloroacetaldehyde
Authors: Durig J. R. , Natter W. J. 
Published: May 2005

AbstractThe Raman spectrum of gaseous trichloroacetaldehyde (chloral) has been recorded from 20 to 3200 cm−1. A series of three transitions (83, 76, 69 cm−1) has been observed for the low frequency torsional mode. The barrier to internal rotation has been calculated to have a value of 1.17 kcal mol−1 (409 cm−1) in the gaseous phase. This value is compared to the corresponding quantity in similar molecules.
Resonance Raman studies of transition metal peroxo complexes: 4‐The potassium μ‐Peroxo‐bis[pentacyanocobaltate(III)], K6[(CN)5CoO2Co(CN)5]·H2O and μ‐superoxo‐bis‐[pentacyanocobaltate(III)], K5[(CN)5CoO2Co(CN)5]·H2O complexes
Authors: Hester R. E. , Nour E. M. 
Published: May 2005

AbstractResonance Raman spectra for the peroxide K6[(CN)5CoO2Co(CN)5]·H2O and superoxide K5[(CN)5CoO2Co(CN)5]·H2O complexes have been determined using several different excitation wavelengths. The peroxide spectrum shows a number of strong resonance bands at 141, 174, 408, 602, 804, 1594 and 2369 cm−1 which are assigned to the vibrational modes of the central unit CCoO2CoC (C of the axial CN) as δ(OCoC), δ(CoO2), ν(CoC), ν(CoO), ν(OO), 2ν(OO) and 3ν(OO), respectively. This is confirmed by the measurements of the 18O‐enriched complex. Intensity excitation profiles of these bands demonstrate that the resonance effect is associated with a CT transition of the type O22− ‐Co3+ assigned at 327 nm and that the carbon atoms of the two trans axial cyanides are involved in this electronic transition. The ν(OO) harmonic frequency (ω1) and anharmonicity constant (X11) are shown to be 818 and −7 cm−1, respectively. The superoxide spectrum shows a band at ∼1100 cm−1 assigned to the ν(OO) mode. The resonance effect of this band is shown to be associated with the O2− ‐Co3+ CT transition assigned at 485 nm. For both complexes, plots of [IJcorr]1/2 against the Shorygin function [1+ (νexc/νe)2]/[‐(νexc/νe)2]2 give straight lines from which the value of α′ for OO band in the superoxide is calculated to be twice as big as that in the peroxide complex. This is in agreement with the calculated force constants which show that the superoxide link is ∼1.93 times stronger than the peroxide link, while the CoO is ∼1.4 times weaker in the superoxide complex. Infrared absorption measurements show no bands that are related to ν(OO) or ν (CoO) in either of the complexes.
Etude, par Spectroscopie de Vibration, du Composé 4HNO3·H2O dans les Etats Cristallisé, Vitreux et Liquide Mise en Evidence du Trihydrogénotétranitrate d'Oxonium
Authors: Thi M. Pham , Herzog‐Cance M. H. , Potier A. , Potier J. 
Published: May 2005

AbstractThe IR and Raman spectra of the mixture 4HNO3 · H2O in crystal, glassy and liquid states have been investigated in the frequency range 4000–50 cm−1. The crystal is the oxonium trihydrogentetranitrate where the oxonium ion is practically free (ν(OH) = 3480 and 3385 cm−1). In the trlhydrogentetranitrate ion the charge is not localized. In the glassy and liquid states, four species have been characterized: (1) the oxonium trihydrogentetranitrate; (2) the free molecular association H2O …︁ (HONO2) (νOH(H2O)= 3550 cm−1 and ν OH(HNO3)=2930 cm−1); (3) the free ionic pair (H2OH)+…︁(ONO2)− (ν(OHO)= 2700 cm−1, ν1(NO3−)=1030 cm−1) and (4) free HNO3 molecules (ν(NOH)=926 cm−1).
The Raman band shape and vibrational relaxation of the ν1 mode of SO42− in Na2SO4 and (NH4)2SO4 aqueous solutions
Authors: Fujita Kazuyoshi , Kimura Masao 
Published: May 2005

AbstractThe Raman band of the ν1 vibrational mode of SO42− has been measured in aqueous solutions of Na2SO4 and (NH4)2SO4 at 5–80°C, and analysed from the stochastic point of view. The band shape is approximately symmetric, but cannot be reproduced by a Lorentzian curve. The vibrational relaxation is caused by a random modulation of very low frequency from surrounding water. The vibrational correlation time for the ions is not sufficiently long to make allowance for the Markovian process of relaxation, compared with the correlation time for the bath, that is water. The vibrational correlation function appropriate for these ions is proposed.
Etude Vibrationnelle de trans ‐Dicyano‐4,5 Cyclohexènes: 1—Spectres Raman et IR de Dicyano‐4,5 Cyclohexènes; Spectres Raman de Monocristaux
Authors: Davidovics G. , Gedoux B. , Aycard J. P. , Pourcin J. 
Published: May 2005

AbstractComparison of Raman and IR spectra of D0; ‐4,5 D2; ‐3,3,6,6 D4 trans‐4,5 dicyano cyclohexenes and study of polarized Raman spectra of D0 and D4 single crystal varieties allowed to classify in the A and B symmetry classes the 48 normal modes of these molecules specifying those which originate from (HCCN)2 sequence. A conformational effect was found from the dissolved molecules spectra investigation.
Raman spectra of the rare earth orthophosphates
Authors: Begun G. M. , Beall G. W. , Boatner L. A. , Gregor W. J. 
Published: May 2005

AbstractRaman spectra of anhydrous crystalline samples of all of the lanthanide orthophosphates (with the exception of PmPO4) have been obtained. These data were interpreted in a systematic manner based on the known structures of these compounds. Assignments and correlations have been made for many of the observed bands.
The vibration‐rotation Raman spectrum of P4
Authors: Brassington N. J. , Edwards H. G. M. , Long D. A. 
Published: May 2005

AbstractThe vibration‐rotation Raman spectrum of the ν2 fundamental band of P4 has been recorded photographically using a spectrograph with a reciprocal linear dispersion of 1.36 cm−1 mm−1. Analysis of the spectrum gave the following values for the vibration and rotation constants and the PP bond length: magnified image
The temperature dependence of the low frequency modes in the Raman spectra of ammonium perrhenate and potassium perrhenate
Authors: Korppi‐Tommola J. , Brown R. J. C. , Shurvell H. F. , Sala O. 
Published: May 2005

AbstractThe temperature dependence of the Raman spectrum of potassium perrhenate is reported. Some new detailed results on the temperature dependence of the low frequency Raman bands of ammonium perrhenate are also presented. The frequency versus temperature plots for both internal and external modes of the ReO4− ion in KReO4 appear to be linear over the temperature range from 20 to 300 K. This is in contrast to the non‐linear behaviour of the external modes of the ReO4− ion in NH4ReO4. A crossing of the frequencies of the Ag and Eg librational modes of the ReO4− ion in NH4ReO4 occurs near 200 K, the temperature at which anomolies have been observed in the temperature dependence of several physical properties of this salt. The apparent discontinuities near 200 K in the slopes of the wavenumber versus temperature curves reported earlier1 are now shown to be shoulders on smooth curves. Extrapolation of the frequency versus temperature plots of the Eg and Bg translational modes of the ReO4− ion in KReO4 indicates that a crossing of the curves would occur at about 500 K, while for NH4ReO4 the crossing of the frequencies of these modes is observed near 200 K. The significance of these observations with respect to the structure and a possible higher order phase transition in the NH4ReO4 crystal is discussed.
Composition of a gaseous mixture in chemical equilibrium as studied by Raman spectroscopy: Gas phase acetic acid
Authors: Gaufrès Robert , Maillols Jacques , Tabacik Vlado 
Published: May 2005

AbstractAn experimental method for the determination by Raman spectroscopy of the composition of a gas mixture in which a chemical equilibrium occurs, and the related processing of the data are discussed. Acetic acid vapour, for which none of the components of the equilibrium can be isolated, is chosen as an example. The intensities of the ν(CC) bands are taken as monitors for the concentrations of monomer and dimer species. The mixture has been studied at 120°C and 155°C, in the pressure of c. 0.2–1.5 atm. Using gas density data, a treatment in terms of molal concentrations leads to consistent results, the ratio of Raman scattering cross‐sections at the wavenumbers corresponding to the ν(CC) vibrations (dimer/monomer) being found the same for both isotherms and equal to 1.64. The other significant results are: Kc app = 0.48 atm. at 120°C and 2.67 atm. at 155°C. ΔH (dissociation of one mole of dimer) = 16.3 kcal (range 120–155°C). An alternative treatment in which an ideal behaviour of the gas phase is assumed shows that Raman measurements are accurate enough to emphasize the inadequacy of this approximation in the temperature and pressure range considered. The Raman spectrum of gaseous acetic acid (range 100–3700 cm−1) at ∼220°C and ∼2 atm is presented.
Reorientational dynamics of liquid CH3CCl3 by Raman spectroscopy
Authors: Tsai Nora H. , Baglin Frank G. 
Published: May 2005

AbstractSpontaneous Raman spectra of the 2940 cm−1 signal of liquid 1,1,1‐trichloroethane (TCE) were studied in order to obtain information concerning the molecular reorientation process. The reorientational correlation time was measured as a function of temperature between 255 and 298K giving an activation energy of 2.6 cal mol−1 for the tumbling motion of neat liquid TCE. Experimental results were compared with those from extended J‐diffusion model, microviscosity theory and previous work. It was found that the TCE molecules underwent small‐step rotational diffusion. The large variation of the reorientational correlation functions and rotational correlation times of TCE in dilute solutions of CCl4, CDCl3 and CD3CN suggested that the dipole moment contribution is an important factor in molecular reorientation in solutions as suggested by Larkin.
Picosecond multichannel Raman spectrometry of solids
Authors: Bridoux M. , Deffontaine A. , Delhaye M. , Rose B. , Silva E. Da 
Published: May 2005

AbstractA new multichannel Raman spectrometer has been developed and for the first time spontaneous Raman spectra of solids excited by a single laser pulse of 25 ps have been recorded.
Raman linewidth study of molecular complexes of chloroform with ether
Authors: Tanabe Kazutoshi 
Published: May 2005

AbstractLinewidths of isotropic and anisotropic Raman bands of the CD stretching mode of chloroform‐d have been measured in ether and in carbon tetrachloride, and the hydrogen bonding between chloroform and ether has been investigated from the analysis of the linewidths. Theoretical Raman linewidths due to vibrational and reorientational relaxation have been calculated for two models. One is a non‐hydrogen‐bonded model where a single chloroform molecule is surrounded by ether molecules without forming hydrogen bonds, and the other is a hydrogen‐bonded model where a chloroform‐ether complex as a solute is surrounded by ether molecules. The concentration dependences of experimental Raman linewidths are discussed in relation to these two models.
Raman spectra of ammonium sulphamate single crystal
Authors: Raj A. Sundara , Muthusubramanian P. 
Published: May 2005

AbstractRaman scattering from single crystals of ammonium sulphamate have been recorded in the region 30–3400 cm−1 with He‐Cd laser excitation. The libratory and translatory modes observed in all the six polarizations were assigned. The assignment of internal modes of ammonium ion indicates minimum distortion of the ion from the tetrahedral symmetry. The presence of medium hydrogen bonding and the range of correlation field splitting are discussed.
Infrared and Raman study of amorphous V2O5
Authors: Sanchez C. , Livage J. , Lucazeau G. 
Published: May 2005

AbstractAmorphous V2O5 can be obtained by cooling from the melt. This amorphous oxide is very sensitive to water vapour and can even be dissolved in water to give a vanadium pentoxide gel. The hydration process has been followed by infrared and Raman spectroscopy between 20 and 4000 cm−1. Short‐range order in the amorphous oxide appears to be almost the same as in orthorhombic V2O5. The amorphous phase could even be described as made of small crystallites about 100 Å in diameter. The structure of amorphous V2O5 does not seem to be modified by water adsorption, at least during the first stages of the hydration process. However, a drastic modification occurs when enough water is added to give a gel. A general shift to lower frequencies is observed, indicating a weakening of the VO bonds, presumably associated with the formation of new VOH2 bonds. Two different water species have been identified, one of which seems to be almost free of hydrogen bonding. Short‐range order in the gels seems to be quite well defined and the spectra could be interpreted either in terms of crystallites, as in amorphous V2O5, or in terms of molecular (or macromolecular) species containing V2O5, (H2O), groups.
Resonance Raman spectra of short‐lived species of photochromic 2‐ and 4‐(2′,4′‐dinitrobenzyl)pyridine
Authors: Takahashi Hiroaki , Kobayashi Yoko , Kaneko Norio , Igarashi Takashi , Yagi Ichiro 
Published: May 2005

AbstractResonance Raman spectra of photo‐activated transient blue species of 2‐(2′,4′‐dinitrobenzyl)pyridine and 4‐(2′,4′‐dinitrobenzyl)pyridine have been measured in methanol solutions using a dual beam pump/probe laser technique and a continuous flow method. Comparison of the Raman spectra with those of N‐methyl derivatives of both compounds and with those of 1‐methyl‐2‐pyridonemethide and dehydrogenated 5‐nitro‐o‐toluic acid indicates that the transient blue species of both compounds take an NH quinoid form and not an aci‐nitro form. The photo‐activated blue species of 4‐(2′,4′‐dinitrobenzyl)pyridine in the molten state is found to be identical with the transient species of the same compound in solution.
Conformation‐dependent Raman bands of phospholipid surfaces. 3—head group Ortho‐phosphate stretching vibrations
Authors: Bicknell‐Brown Ellen , Brown Kenneth G. , Person Willis B. 
Published: May 2005

AbstractVibrational frequencies of diethyl phosphate were calculated for rotamers for which the dihedral angle about the PO and CO bonds varied. The frequencies predicted for the symmetric and antisymmetric OPO stretches, the symmetric and antisymmetric ionic PO2− stretches, and the CC stretches are found to be sensitive to the PO and CO dihedral angles. The results of Raman temperature and solvent studies of diethyl phosphate are reported and are found to be in good agreement with the conclusions obtained from the normal coordinate analyses. Frequencies of diethyl phosphate rotamers having the geometries of crystalline glycerophosphorylcholine (GPC), crystalline GPC CdCCl2, and amorphous GPC CdCl2 were calculated and compared to the Raman spectra of these phospholipid head group models. The normal coordinate analyses are in good agreement with Raman spectra. These results indicate that the observed frequencies of phosphate group vibrations may be compared to the normal coordinate analyses of diethyl phosphate rotamers to monitor conformation in phospholipid head groups (and other organic ortho ‐phosphates). The Raman symmetric OPO stretch bandwidth may be used to monitor rotational freedom or broadening due to the distribution of differing conformations.
Raman and infrared studies on new anticancer inorganic ring systems. 1—hexaziridinocyclotriphosphazene N3P3(NC2H4)6
Authors: Manfait Michel , Alix Alain J. P. , Labarre Jean‐François , Sournies François 
Published: May 2005

AbstractThe Raman spectra of the new anticancer agent N3P3(NC2H4)6(MYKO 63), in the solid state and in aqueous solution, and the infrared spectra of the molecule in the solid state, are reported for the first time. All the assignments are discussed in terms of the following vibrations framework (N3P3); ligand (NC2H4); and framework‐Iigand couplings (Nendo2PNexo2). The concept of group frequencies associated with local symmetrical valence coordinates is used extensively.
Two accurate methods to obtain the spectral sensitivity of a Raman spectrometer device
Authors: Ouillon R. , Adam S. 
Published: May 2005

AbstractWe have compared the spectral transmission coefficient of a Raman spectrometer and photomultiplier device determined (a) from a continuous spectrum (calibrated tungsten lamp) and (b) from the spectrum of the rotational Raman lines of D2 molecules. The two methods give a similar sensitivity curve as a function of wavelength. However the first method is more accurate in the determination of the spectral response over a wide spectral range (˜3000 cm−1 or more); and the second method is better than the first for obtaining accurate value of the intensity of the Raman lines and their absolute scattering cross sections.
Structural conclusion on the Schiff base group of retinylidene chromophores in bacteriorhodopsin from characteristic vibrational bands in the resonance Raman spectra of BR570 (all‐trans), BR603 (3‐dehydroretinal) and BR548 (13‐cis)
Authors: Massig G. , Stockburger M. , Gärtner W. , Oesterhelt D. , Towner P. 
Published: May 2005

AbstractBacteriorhodopsin the protein of the purple membrane of Halobacteria, involves a retinylidene Schiff base as its photochemically active chromophore. Resonance Raman spectra, which selectively probe the retinylidene Schiff base chromophore, were obtained from aqueous suspensions of the purple membrane. In the unphotolysed chromophore Bacteriorhodopsin, the Schiff base nitrogen carries a proton whose reversible release during a photo‐induced cyclic process is essential for the ability of the purple membrane as a proton pump. It is expected that during this process the Schiff base group undergoes conformational and/or configurational changes, the elucidation of which is important for an understanding of the proton pump mechanism. We have looked for resonance Raman bands characteristic of the terminal group =C14HC15H=NH+‐ of the retinylidene Schiff base chromophore in BR570. Vibrational modes could be assigned on the basis of deuterium exchange at C15 and replacement of the Schiff baèe proton by a deuteron. Resonance Raman spectra of BR603, a chromophore with an additional double bond in the retinal ring (3‐dehydroretinal) but an identical terminal group, were also used for this analysis. Various types of hydrogen bending modes could be identified. From resonance Raman theory it was concluded that the intensities and frequencies of such modes reflect the conformation (bending and twisting angles) of the terminal group. A comparison of the resonance Raman spectra of BR570 (all‐trans) and the 13‐cis component BR548 from the dark‐adapted purple membrane revealed that the conformation of the protonated Schiff base is significantly different in these two chromophores. This is ascribed to variable interactions with the protein. The relation between resonance Raman spectroscopic data and the conformational structure of the terminal group is discussed on the basis of a simple model. From the results of this paper it is suggested that important structural information from resonance Raman spectroscopic data can also be obtained for retinylidene Schiff base chromophores in intermediates of the photochemical cycle.
Variable temperature and pressure Raman spectra of potassium azide KN3
Authors: Khilji M. Y. , Sherman W. F. , Wilkinson G. R. 
Published: May 2005

AbstractPolarized Raman studies have been carried out on a single crystal of potassium azide as a function of temperature and band assignments have been made. The Raman spectrum of KN3 microcrystalline samples as a function of pressure is reported.
Raman spectra of halogen‐substituted methanes in the liquid state. 2—Band widths of the totally symmetric vibration bands
Authors: Fukushi Kohji , Kimura Masao 
Published: May 2005

AbstractThe isotropic and anisotropic Raman band widths of the totally symmetric vibrations of halogen‐substituted methanes have been measured in the liquid state at room temperature. The isotropic CH and CD stretching vibration bands broaden with increasing molecular weight and this is qualitatively explained by the Fischer‐Laubereau dephasing model. The isotropic band widths of the deformation vibrations are correlated with the reorientational correlation times and are attributed to broadening due to interactions dependent on the orientation, such as the dipole–dipole interaction.