bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibrational spectra of β‐LiVOPO4 and NaVOPO4
Authors: Baran Enrique J. , Vassallo Marta B. , Lii Kwang‐Hwa 
Published: May 2005

AbstractThe infrared and laser Raman spectra of β‐LiVOPO4 and NaVOPO4 were recorded and are briefly discussed with the aid of factor group analyses, based on recently reported structural data. Some spectroscopic features related to the characteristics of the VO and PO bonds in these compounds are also commented upon.
Vibrational spectra for purine and its 15N‐ and D‐substituted analogues. Assignment of normal modes from ab initio 3–21G force fields
Authors: Majoube M. , Henry M. , Vergoten G. 
Published: May 2005

AbstractFourier transform (FT) IR and FT‐Raman spectra for purine and its N‐, C8‐ and N‐ and C8‐deuterated analogues and for that 15N‐substituted on the pyrimidine ring are reported. Experimental data are interpreted by reference to ab initio‐calculated wavenumbers for normal modes of both N7H‐ and N9H‐purines. The latter were obtained from normal coordinate analyses carried out on the basis of ab initio 3–21G force fields using the optimized geometry. The effect of hydrogen bonding on the discrepancy between calculated and observed wavenumbers for normal modes was analysed. Considering the solid N7H‐purine, the observed 15N shifts for FT‐IR bands often agree with those calculated for the corresponding normal modes. Several weak bands are tentatively assigned to the N9H tautomer, presumably present in small amounts in solution and also in the solid in the case of deuterated purines.
Vibrational spectral analysis of Eosin Y and Erythrosin B—intensity studies for quantitative detection of the dyes
Authors: Narayanan V. Anantha , Stokes David L. , Vo‐Dinh Tuan 
Published: May 2005

AbstractThe complete vibrational spectra of Eosin Y and Erythrosin B were recorded using Fourier transform Raman and Fourier transform infrared spectroscopy. The surface‐enhanced Raman scattering (SERS) spectra of these two dyes were also studied using an intensified charge‐coupled detector (ICCD) Raman spectrophotometer operated with 5 mW laser power. The intensities of the intense alternating CC bond wavenumbers of the aromatic ring at 1333 cm−1 in Eosin Y and 1317 cm−1 in Erythrosin B were measured as a function of the analyte concentration of these dyes. Calibration graphs of concentration of the dyes in ethanol solution against photon counts are presented. The limits of detection of these two bands in the SERS spectra were determined.
Deconvolution of lorentzian Raman Linewidth: Techniques of polynomial fitting and extrapolation
Authors: Singh Ranjan K. , Singh S. N. , Asthana B. P. , Pathak C. M. 
Published: May 2005

AbstractA simple, convenient and precise technique for deconvolving the Lorentzian (true) Raman linewidth, ΓL, from the observed Raman linewidth, (Δ1/2)R [the FWHM (full width at half‐maximum) of the Raman line in question], through polynomial fitting, was developed. The precision of this technique is a consequence of the fact that the values of ΓL/(Δ1/2)R (= Y), obtained by exact numerical evaluation of the Voigt profiles for the Raman bands, were flitted to third‐ and fourth‐degree polynomials in S/(Δ1/2)R (= X), S being the spectral slit width measured as the linewidth (FWHM) of a narrow spectral line recorded at the same slit settings as the Raman line. The procedure of obtaining ΓL, from the knowledge of S,(Δν1/2)R and X, which yields better results, is discussed. Another technique of deconvolution is described and discussed, involving the measurement of Raman linewidths of a particular Raman line for about five or six different slit widths. The measured linewidths (Δ1/2)R, when extrapolated to S → 0, give the value of ΓL directly. A careful comparison with the other deconvolution techniques reveals that the method of polynomial fitting is relatively more precise than other semi‐analytical deconvolution techniques, and the extrapolation technique also gives reasonably good results. The applicability of both methods was tested by taking some selected Raman lines.
Optical and resonance Raman scattering study of two ‘bisazo’ pigments derived from substituted benzene‐2′‐azonaphthols
Authors: Sourisseau C. , Maraval P. 
Published: May 2005

AbstractThe UV‐visible (300–800 nm), Raman and resonance Raman (900–1700 cm−1) spectra of two bisazo scarlet RN and brown 5R pigments have been investigated in the solid state at 300 K. A detailed analysis of the resonance Raman spectra and excitation profiles of various fundamentals in the 900–1700 cm−1range is reported through the visible absorption spectrum region: the vibrational assignments confirm that both substituted benzene‐2′‐azonaphthol derivatives are stabilized in their hydroxyazo form; the excitation profiles (EPs) established for many modes in each dye indicate interferences between two overlapping electronic manifolds. Taking account of multistate interference phenomena and inhomogeneous broadening effects, the observed EPs compare well with the calculated ones under the assumption of weakly displaced harmonic oscillators; this interpretation is supported by the observation of weak overtone and combination bands in the 1700–3000 cm−1range.Finally, conclusions are drawn about the scattering mechanisms and the nature or degree of mixing of the first electronic excited states, which appear to be quite sensitive to the substituent (Cl or NO2) on the benzene rings. Such information can be helpful for the design and synthesis of new azo dyes with desirable properties.
A resonance Raman polarization study of the mode‐specific subpicosecond photodissociation of the NO2 22B2 state
Authors: Fan R. , Ziegler L. D. 
Published: May 2005

AbstractVibronically specific subrotational period lifetimes of the predissociated 22B2 state of NO2 vapour (250–235 nm) have been determined by spontaneous resonance Raman scattering polarization measurements. The lifetimes of the vibronic symmetric stretching, ν1′, (100), bending, ν2′, (101), and asymmetric stretching, ν3′, (002), overtone levels are 75 ± 10 fs, 2.5 ± 05 ps and 155 ± 15 fs respectively. When one quantum of bending (ν2,′) is excited in combination with one quantum of totally symmetric stretching (ν1′), the lifetime increases from 75 ± 10 to 125 ± 15 fs (110). The 22 B2 state electronic origin lifetime has been previously shown to be 42 ± 5 ps independent of angular momentum quantum numbers. These results are interpreted in terms of the shape of the potential energy surface intersections in the region and the results of earlier quantum yield measurements.
Adsorption of 4‐hydroxybenzoic acid on silver investigated by surface‐enhanced Raman scattering
Authors: Kwon Yong Joon , Park Sung Soo , Kim Kwan , Kim Myung Soo 
Published: May 2005

AbstractSurface‐enhanced Raman scattering (SERS) of 4‐hydroxybenzolc acid (4HBA) was investigated in a silver sol and at a silver electrode. The adsorption behaviour of 4HBA on the sol surface appeared different from that on the electrode surface. It was concluded that the molecule binds to the sol particle surface as either oxidobenzoate or hydroxybenzoate assuming a flat orientation. The former species that was bonded to silver via both the lone pair electrons of the oxido group and the π orbitals of the carboxylate group was more stable in a basic environment On the electrode surface, the molecule seemed to bind as hydroxybenzoate mainly through the oxygen lone pair electrons of the carboxylate group, with the hydroxyl group being pendent to the surface. From the pH dependence of the SER spectral pattern, the acid strength of the hydroxyl group was estimated to become 104 times stronger on the sol surface in comparison with that in the bulk. The nature of the different adsorption mechanisms observed on the sol and electrode surfaces is not yet certain. Tentatively, the difference was attributed to the different surface morphology along with the intrinsic difference in the nature of SERS active sites on the two surfaces.
Vibrational spectroscopic studies of aqueous dextran sulphate
Authors: Siew Diana C. W. , Cooney Ralph P. , Taylor Michael J. , Wiggins Philippa M. 
Published: May 2005

AbstractThe interaction between water and polyelectrolytes was investigated using aqueous dextran sulphate systems. The results indicated that the hydrogen‐bonding network of water in the system is affected by the presence of a highly charged polyanion with both surface hydrophobic and hydrophilic sites. This is reflected in the spectral profile of the OH stretching mode of water in the region 3000–4000 cm−1. Comparison with aqueous sodium methyl sulphate and sodium sulphate systems suggests that two regions of water are present in the dextran sulphate system. Water in the region associated with the hydrophobic carbohydrate skeleton appears to be more strongly hydrogen bonded than bulk water whereas that in the vicinity of the hydrophilic SO3 − groups is more weakly hydrogen bonded. Variations in the vibrational spectra were dependent on the extent of the different populations of water present and can be explained by invoking the concepts of long‐range intermolecular coupling. Analysis of the dextran skeletal bands in the region 750–1850 cm−1 confirmed that the SO3 − sites play an important role in the hydration of dextran sulphate. The presence of two symmetric SO3− stretching modes in the Raman spectra of these systems, both of which are sensitive to the hydration state of the molecule, has been explained in terms of a model based on non‐equivalent SO3 − sites.
Raman excitation profiles of metal dithiolenes: Comparison between the transform method and time‐dependent theory
Authors: Ribeiro M. C. C. , Barreto W. J. , Santos P. S. 
Published: May 2005

AbstractThe time‐dependent theory of the resonance Raman effect was employed for the calculation of the Raman excitation profiles and optical absorption spectra of the meial dithiolene species [Zn(dmit)2]2− and [Ni(dmit)2]2− (dmit = 4,5‐dimercapto‐1,3‐dithiolc‐2‐thionc) The model adopted takes into account the three normal modes notable for their enhancement at resonance, and embodies the linear non‐Condon coupling contribution. Previous calculations for these species using the transform method lead to estimates of the relative displacements of potential surface minima for the three modes considered, while the present calculations led to absolute values for such displacements. The metal‐sulphur bond length is increased by 0.016 and 0.027 Å in the zinc and nickel complexes, respectively.
Raman spectroscopic study of ion association in aqueous magnesium sulphate solutions
Authors: Rull F. , Balarew Ch. , Alvarez J. L. , Sobron F. , Rodriguez A. 
Published: May 2005

AbstractA Raman spectroscopic study of aqueous solutions of MgSO4as function of concentration and temperature was performed. From the analysis of the band profile of the internal vibrations of the sulphate ion, the spectroscopic ionic association constant was calculated at different temperatures. It was found that the association is solvent separated in the ranges of concentration and temperature studied. The large differences observed between the values obtained for the spectroscopic association constant and those obtained from macroscopic measurements were interpreted on the basis of a four‐step solvent‐separated dehydration mechanism. It is, assumed that the Raman spectra reflect only the short‐distance force acting on the sulphate anions. The contribution of the long‐range forces for the consecutive steps were calculated using the Bjerrum equation. Good agreement between the overall association constant thus calculated and the macroscopic value was found in the concentration and temperature ranges studied.
Analyse Vibrationnelle et Structurale en Série Aliphatique Saturée. X—Spectres de Vibration de l'Acide Adipique et de ses Sels Alcalins de Potassium en Solution Aqueuse
Authors: Ramsis H. , Monmouton P. , Delarbre J. L. , Maury Et L. 
Published: May 2005

AbstractLes spectres infrarouge et Raman de l'acide adipique et de ses sels de potassium en solution aqueuse ont été analysés. Une attribution des fréquences fondamentales est proposée. L'analyse de l'état de polarisation des raies Raman montre que les deux sels appartiennent au groupe de symétrie Cs tandis que l'acide répond au groupe de symétrie C1. A l'état cristallin, le sel acide est de type A selon la classification de Speakmann. Une comparaison des conformations avec celles déterminées en série alcanedioique a été réalisée.
Dispersion of the oblique phonons in tetragonal BaTiO3 and Ce: BaTiO3
Authors: Wang Rong‐Ping , Jiang Yi‐Jian , Zeng Ling‐Zhi , Liu Yu‐Long , Zhu Yong 
Published: May 2005

AbstractRaman spectra of oblique phonons in tetragonal BaTiO3 and Ce : BaTiO3 single crystals were obtained for different values of the angle θ which the phonon wavenumber q̄ makes with the c‐axis. On the basis of Merten's equation, the directional dispersion curves were fitted and plotted. The results show that the A1(TO) phonons of BaTiO3 at 275 and 514 cm−1 come from first‐order scattering, which is evidence for the order—disorder model of the ferroelectric phase transition. The Raman spectra of Ce : BaTiO3 are reported for the first time and the results indicate that Ce atoms have little effect on the structure of BaTiO3.
Molecular reorientation in liquid acetonitrile studied by depolarized light scattering experiments
Authors: Giorgini M. G. , Morresi A. , Mariani L. , Cataliotti R. S. 
Published: May 2005

AbstractTime correlation functions from depolarized light scattering experiments at several temperatures were examined by biexponentials that simultaneously account for the unique axis molecular reorientations (on the picosecond time‐scale) and collisional processes (on the subpicosecond time‐scale). The first are found to be systematically slower than those obtained in previous studies. The important role played by dipolar interactions on the molecular organization in the liquid is confirmed. Comparison with dieletric relaxation times indicates that rotational diffusion provides only an approximate description of molecular reorientation in liquid acetonitrile. Application of the J‐diffusion model shows that the exponential decay of the observed orientational correlation functions cannot be taken as evidence of rotational diffusion in liquid acetonitrile.
High‐resolution coherent anti‐stokes Raman spectroscopy of ethane
Authors: Bican T. H. S. , Jonuscheit J. , Lehner U. , Schrötter H. W. 
Published: May 2005

AbstractA continuous‐wave CARS spectrometer was equipped with a new frequency‐stabilized argon ion ring laser and better stabilization for the tunable dye laser was introduced. Special quartz sample cells with Brewster angle windows were placed in the focal region of the argon ion ring laser. A new data acquisition system was installed which allows the simultaneous recording of CARS signals and calibration spectra and the subsequent evaluation of the data. An instrumental resolution of less than 0.001 cm−1 and a wavenumber accuracy of about ± 0.006 cm−1 were achieved. As an example of the performance of the spectrometer, the CARS spectrum of ethane was measured in the region of the CH vibrations at pressures between 95 and 1.9 kPa. The spectra were compared with the stimulated Raman spectrum published recently.
Application of continuous extended scanning techniques to the simultaneous detection of Raman scattering and photoluminescence from calcium disilicates using visible and near‐infrared excitation
Authors: Dyer Chris , Smith Brian J. E. 
Published: May 2005

AbstractA novel method of data acquisition is described for spectrographs employing charge‐coupled device (CCD) detection. The technique, called continuous extended (CE) scanning, allows data collection over the full spectral range of the spectrograph, rather than a limited window determined by the wavelength, spectral dispersion, spectrograph focal length and detector dimensions. The CE method removes the need to sacrifice resolution for spectral range or the need to record and splice many spectral segments to reproduce a full‐range spectrum. The advantages of this method are discussed and the capability is demonstrated with respect to several calcium disilicate minerals, recently shown to exhibit intriguing behaviour under near‐infrared (NIR) excitation, including intense photoluminescence. Data obtained using both visible (514.5 nm) and NIR (779.1 nm) excitation are presented and the results are briefly discussed in the light of recent Fourier transform Raman studies using 1064.1 nm excitation.
The Raman spectrum of toluene vapour
Authors: Bican T. H. S. , Schrötter H. W. , Grošev V. Mohaček 
Published: May 2005

AbstractThe rovibrational Raman spectrum of toluene vapour at a pressure of 3 kPa was recorded photoelectrically at medium resolution. The sample was contained in a Brewster angle cell in the cavity of the argon ion ring laser of a CARS spectrometer, the scattered light being transferred to the Raman spectrometer by a fibre‐optic bundle. Nine fundamental bands, eight a1′ and one a2″, and some overtone bands were observed and assigned.
Specific molecular interactions of acridine drugs in complexes with topoisomerase II and DNA. SERS and resonance Raman study of m‐AMSA in comparison with o‐AMSA
Authors: Chourpa Igor , Manfait Michel 
Published: May 2005

AbstractMolecular interactions of a potent DNA‐topoisomerase II (Topo II) inhibitor, m‐AMSA [4′‐(9‐acridinylamino)methanesulphon‐m‐anisidide] and of its less active isomer o‐AMSA in complexes with plasmid DNA, Topo II and Topo II‐mediated ternary cleavable complexes were studied by means of surface‐enhanced Raman scattering (SERS) spectroscopy. Models for the participation of these drugs in the complexes were proposed according to the analysis of the main vibrational modes of the acridine chromophores in the SERS and resonance Raman (RR) spectra of m‐AMSA in comparison with the structurally close derivatives o‐AMSA and 9‐aminoacridine (9AA). It was found that, under the conditions used, the adsorption on the silver colloid does not perturb the Raman spectra of acridine chromophores. The SERS data indicate the intercalation of the planar acridine moiety within DNA for 9AA and for both o‐AMSA and m‐AMSA, without pronounced differences for the meta and ortho isomers. The DNA intercalation is likely to involve a μ‐μ interaction between the acridine and DNA base pairs, but without contacts via the nitrogen of the acridine ring. This is because the spectral changes observed in the drug‐DNA complexes of m‐and o‐AMSA are different from those observed on acridine deprotonation. In fact, it is the NH group of the side‐chain of the drug that we propose to interact with the negatively charged phosphates or edges of DNA and stabilizes the arrangement of the external anilino ring in the minor groove of DNA. The DNA intercalation seems to be present for the acridine moiety of both isomers in the ternary cleavable complexes. However, in the latter the side‐chain of m‐AMSA, but not of o‐AMSA, has been found additionally to participate in specific (enzymatic activity‐dependent) interactions with Topo II. The SERS data indicate the ability of m‐AMSA to interact specifically with the enzyme alone. The specific m‐AMSA‐Topo II interactions on formation of the cleavable ternary complex and/or directly with the enzyme should play a key role in the Topo II inhibition and therefore in the anti‐tumour activity of the drug.
Non‐exponential dephasing of molecular vibrations in liquids, directly observed by ‘magic’ femtosecond CARS
Authors: Lindenberger F. , Rauscher C. , Purucker H.‐G. , Laubereau A. 
Published: May 2005

AbstractUsing ‘magic’ polarization geometries in time‐resolved coherent anti‐Stokes Raman spectroscopy, the isotropic (purely vibrational) scattering contribution was investigated. Non‐exponential dephasing was observed on the subpicosecond time‐scale, described in the Anderson‐Kubo formalism by the correlation time τc. Experimental data are reported for the neat liquids CH2BrCl and (CH3)2SO in the CH stretching region. Values of τc = 330 fs and 240 fs, respectively indicate, homogeneous line broadening for the dephasing processes. The time‐domain data are supported by a novel analysis of spontaneous Raman data.
UV resonance Raman spectroscopy of cis—‐amides
Authors: Jordan Trace , Spiro Thomas G. 
Published: May 2005

AbstractUV resonance Raman (UVRR) spectroscopy with 210 nm excitation was used to study the cis‐amide bonds of caprolactam (CAP) and cis‐N‐methylacetamide (NMA) in aqueous solution. The UVRR spectrum of CAP is dominated by an intense stretching mode at 1492 cm−1, designated amide cII, which is assigned to a localized CN stretching vibration. The amide cI mode, described as a C=O stretch, can be located at 1621 cm−1 using Fourier transform IR spectroscopy. Photoisomerization of NMA with high laser power, followed by subtraction of the trans‐NMA spectrum, is used to generate the isolated UVRR spectrum of cis‐NMA and its (C)CD3, (N)CD3 and (C,N)CD3 methyl isotopomers. The spectrum of cis‐NMA is also dominated by an intense amide cII band at 1495 cm−1, and a weak band at 1623 + 3 cm−1 can be assigned to amide cI. The amide cII mode is strongly mixed with vibrations of the (N)CH3 group, as revealed by its 24 cm−1 downshift upon (N)CD3 substitution, but no isotopic sensitivity is observed for (C)CD3 substitution. Studies of CAP in various solvents show linear correlations between amide cI and cII wavenumbers and the solvent acceptor number, where amide cI downshifts and amide cII upshifts in hydrogen bonding solvents. However, the slope of the wavenumber dependence for the cis‐amide modes of CAP is smaller than for the corresponding trans‐amide modes of NMA and cannot be attributed to the differences in mode composition. This behavior is ascribed to different orientations of the ground‐state dipole for amides in trans and cis configurations. Finally, the selective enhancement of cis‐amide modes at 210 nm excitation was applied to monitor the increase in equilibrium population of cis‐NMA with increasing temperature. A Van't Hoff plot of the spectral data to calculate ΔH for cis‐trans isomerization yielded values of 1.9 + 0.2 kcal mol−1 from peak heights and 1.7 + 0.2 kcal mol−1 from peak areas (1 kcal = 4.180 kJ), which are in good agreement with previously published theoretical and experimental results.
New assignment of crystalline and ion‐irradiated graphite phonon spectra
Authors: Compagnini Giuseppe , Baratta Giuseppe A. , Cataliotti Rosario Sergio , Morresi Assuntina 
Published: May 2005

AbstractA comparison was made between the Raman spectra of virgin and ion‐irradiated highly oriented pyrolytic graphite, relating them with their infrared spectra. Structural modifications, after ion beam irradiation at moderate ion fluences (0.2 eV per carbon atom, average deposited energy), were detected and a careful vibrational analysis was made in the light of the correlation between site and factor group symmetries of the graphite infinite crystal. This allows a new proposal for the assignment for the so‐called G and D lines of the Raman phonon spectra. Interaction effects, of the type projectile‐target, are envisaged to explain spectroscopic modifications of ion‐irradiated graphite.
Polarized Raman spectra and intensity analysis of Na4P2O7. 10H2O and PO stretches in (VO)2P2O7
Authors: Kanesaka Isao , Ozaki Kenichi , Matsuura Ikuya 
Published: May 2005

AbstractThe polarized Raman spectra of Na4P2O7 .10H2O and the infrared and Raman spectra in the polycrystalline state were recorded at room temperature. A normal coordinate analysis of Na4P2O7.10H2O and Raman and infrared intensity analyses in the P—O stretching region were carried out and the force field and the intensity parameters for the P2O ion obtained. These results were transferred and used to analyse the P—O stretches in (VO)2P2O7, whose infrared spectrum depends largely on the preparation method. It is concluded that α‐(VO)2P2O7 corresponds to the Gorbunova and Linde structure, while the γ‐form probably has disordered (VO) sites.