bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of homogeneous and inhomogeneous broadening on resonance CARS excitation profiles
Authors: Materny A. , Kiefer W. 
Published: May 2005

AbstractThe influence of broadening due to intrinsic molecule and ensemble properties (homogeneous and inhomogeneous broadening) on resonance CARS excitation profiles (CEPs) was investigated by means of a theoretical model. The non‐linear susceptibility χ(3) of a homogeneous ensemble of molecules was derived from perturbation theory using a Franck—Condon model and applying a crude Born—Oppenheimer approximation. Then it was assumed that these molecules are situated in an inhomogeneous environment which changes their electronic energies. The CARS intensity for this inhomogeneous ensemble was obtained from the homogeneous CARS intensity taking into account a distribution of energies. The influence of homogeneous and inhomogeneous broadening on CEPs was demonstrated by model calculations and compared with results obtained for resonance Raman excitation profiles. Possible applications are discussed.
Surface Raman scattering of an azo dye in acidic solutions
Authors: Xi Kang , Sharma Shiv K. , Muenow David W. 
Published: May 2005

AbstractThe Raman scattering of azo dye adsorbed on silver sols in acidic solution was investigated and its surfaceenhanced Raman scattering (SERS) spectra and excitation behavior are reported. It was found that different tautomeric species of the azo dye show different SERS enhancements when excited with laser on‐ and off‐resonance frequencies. These observations can be explained by a charge‐transfer model rather than an electromagnetic model.
Normal coordinate treatment of Leu5‐enkephalin in the crystal state
Authors: Lagant P. , Vergoten G. , Shi S. , Zeng G. , Aubry A. , Laureyns J. 
Published: May 2005

AbstractVibrational studies on the neuropentapeptide Leu5‐enkephalin were performed for the crystal state where different specific conformations can arise. In the present case, the peptide adopts a double fused folded conformation (β‐turn), the presence of which in the crystal state is directly related to the nature of the solvent used for its crystallization. This study completes other work relating to similar conformations of isolated molecules. It can be seen that specific interactions in the crystal state perturb to a large extent the vibrational relationships between the amide frequencies and the specific sets of dihedral angles characteristic of the particular type of turn. The tyrosyl moiety and its frequency dependence on its hydrogen bond state was especially investigated both for the Fermi resonance and the hydroxyl bending modes.
Vibrational spectra, ab initio calculations and normal coordinate analysis for 3‐methyl‐3‐vinylcyclopropene
Authors: Baranović Goran , Eckert‐Maksić Mirjana , Golić Mirta , Durig James R. 
Published: May 2005

AbstractThe Raman spectra (3400–10 cm−1) of liquid and solid 3‐methyl‐3‐vinylcyclopropene, C3H2(CH3)CHCH2, and its isotopomer C3D2(CH3)CHCH2 were recorded. The temperature dependence of some band intensities and qualitiative depolarization ratios show that the thermodynamically preferred conformation is s‐trans. The structural parameters and conformational stability of s‐trans and gauche rotamers were obtained from ab initio calculations by employing both 3–21G and 6–31G* basis sets. Barriers to internal rotation and fundamental vibrational frequencies were calculated utilizing the 3–21G basis set. The ab initio results are consistent with the experimentally indicated greater stability of the s‐trans relative to the gauche conformer.
Spectroscopic investigation of lattice vacancies in hexaborides
Authors: Yahia Z. , Turrell S. , Mercurio J.‐P. , Turrell G. 
Published: May 2005

AbstractRaman microprobe and diffuse‐reflectance Fourier transform IR spectra of a series of seven metal hexaborides show that the basic cubic symmetry of these systems is lowered owing to lattice vacancies. The resulting wave vector is oriented along the C4 axis of the first Brillouin zone. Studies of enriched boron samples indicate that the vacancies in the B6 structure are located at boron sites.
Spectroscopic characterization and Langmuir–Blodgett monolayers of N,N′‐unsymmetrical dialkyl‐3,4:9,10‐perylenebis(dicarboximide)s
Authors: Aroca R. , Maiti A. K. , Nagao Y. 
Published: May 2005

AbstractThe spectroscopic characterization of N‐pentyl‐N′‐R‐unsymmetrical dialkyl‐3,4:9,10‐perylenebis(dicarboximide)s (R = CH3, C2H5 and C3H7) is reported. Langmuir monolayers of all three non‐amphiphilic molecules were successfully prepared and transferred to solid substrates. The absorption and fluorescence spectra of solutions and Langumuir–Blodgett (LB) films were studied. Vibrational fundamental frequencies were observed using surface‐enhanced resonance Raman scattering and transmission and reflection–absorption Fourier transform infrared spectroscopy. The formation of aggregates in the ground and excited states (excimer formation) is also discussed.
Spectres de Vibration et Transition de Phase des Complexes Formés Entre l'Acide Oxalique et la Pyridine
Authors: Belabbes Y. , Lautié A. 
Published: May 2005

AbstractRaman and infrared spectra (4000–20 cm−1) of polycrystalline pyridine–oxalic acid complexes were investigated between 80 and 300 K and an assignment in term of group frequencies is given. The 2:2 and 2:3 compounds are spectroscopically identified and the OH…︁O and NH…︁O hydrogen bonds characterized. The spectroscopic results are consistent with crystallographic data. With the deuterated oxalic acid, only one 1:1 complex is obtained and its crystalline structure is different. From spectroscopic analysis, it is found to be built of infinite chains of hydrogenoxalate ions with strong OD…︁O hydrogen bonds (νOD about 1300 cm−1 and estimated Ro…︁o = 2.53 Å). The pyridinium moiety (C5H5ND+) forms ND…︁O hydrogen bonds characterized by a νND frequency of 2130 cm−1 and an N…︁O distance of 2.75 Å. Further, in this compound, one second‐order phase transition is observed at 235 K and the structural modifications are discussed.
Raman and far‐infrared spectra, conformational stability, barriers to internal rotation, vibrational assignment and ab initio calculations of 2‐bromo‐3‐fluoropropene
Authors: Durig D. T. , Guirgis G. A. , Zhen Mengzhang , Durig J. R. 
Published: May 2005

AbstractThe far‐infrared spectrum (375–30 cm−1) of gaseous 2‐bromo‐3‐fluoropropene, CH2C(CH2F)Br, was recorded at a resolution of 0.10 cm−1. The fundamental asymmetric torsional mode is observed at 112.6 cm−1 with four excited states falling to lower frequency for the s‐cis (fluorine atom eclipsing the doubel bond) conformer. For the higher energy gauche conformer, the asymmetric torsion is tentatively assigned to a very weak band at 93.0 cm−1. From these data the asymmetric torsional potential was calculated. The potential function coefficients are calculated to be V1 = 306 ± 5, V2 = −120 ± 4, V3 = 928 ± 6, V4 = 118 ± 2 and V6 = 83 ± 2 cm−1, with an enthaply difference between the more stable s‐cis and higher energy gauche conformers of 200 ± 30 cm−1 [572 ± 86 kcal mol−1 (1 kcal = 4.184 kJ)]. This function gives values of 1009 cm−1 (2.88 kcal mole−1), 1024 cm−1 (2.93 kcal mol−1) and 799 cm−1 (2.88 kcal mol−1), for the s‐cis to gauche, gauche to gauche, and gauche to s‐cis barriers, respectively. From the relative intensities of the Raman lines of the gas at 548 cm−1 (gauche) and 678 cm−1 (s‐cis) as a function of temperature, the enthalpy difference is found to be 196 ± 23 cm−1 (560 ± 66 cal mol−1), and a similar study of the liquid gives a value of 66 ± 4 cm−1 (189 ± 11 cal mol−1) with the s‐cis conformer the more stable rotamer in both of these phases. The s‐cis conformer is the rotamer present in the crystalline solid. The Raman spectrum of the gas was recorded from 3500 to 70 cm−1 and, utilizing these data and previously reported infrared data, a complete vibrational analysis is proposed for both conformers. The conformational stability, barriers to internal rotation and fundamental vibrational frequencies, which were determined experimentally, are compared with those obtained from ab initio gradient calculations employing the RHF/LANL1DZ basis set and/or this basis set with electron correlation at the MP2 level, and with the corresponding quantities for some similar molecules.
Spectroscopic characterization and Langmuir–Blodgett films of N,N‐symmetrical dialkyl‐3,4:9,10‐perylenebis(dicarboximide)s
Authors: Maiti A. K. , Aroca R. , Nagao Y. 
Published: May 2005

AbstractThe electronic and vibrational spectra of N‐R‐N′‐R‐symmetrical dialkyl‐3,4:9,10‐perylenebis(dicarboximide)s (R = C5H11, C6H13 and C8H17) are reported. Langmuir monolayers were prepared and surface pressure–area isotherms were measured for three non‐amphiphilic molecules. Langmuir–Blodgett (LB) films of mixed layers only were fabricated on solid substrates. Fundamental vibrational frequencies were observed using surface‐enhanced resonance Raman scattering, transmission and reflection–absorption (RAIRS) Fourier transform infrared spectroscopy. The molecular orientation in the LB films was established from the transmission and RAIRs spectra. Molecular aggregation is reduced by the presence of bulky alkyl substituents. The adsorption of electron acceptor molecules and its effect on the fluorescence yield are also reported.
Raman spectroscopic determination of boroxol and borate ring contents in lead borate glasses
Authors: Witke K. , Hübert Th. , Reich P. , Splett Ch. 
Published: May 2005

AbstractGlasses in the systemxPbO·(100 –x)B2O3(0 ≤x≤ 30 mol.%) were studied by Raman spectroscopy. The conversion of boroxol rings into borate rings containing one or two BO4groups due to the transformation of threefold to fourfold coordinated boron with increasing content of lead oxide was determined from the intensities of the Raman peaks at 805 and 770 cm−1. Quantitative measurements were carried out on highly finished spherical samples to allow different reflection losses of the samples to be taken into account.
Total internal reflection Raman spectroscopy as a method to study water structure near Langmuir–Blodgett films
Authors: Nickolov Z. S. , Earnshaw J. C. , McGarvey J. J. 
Published: May 2005

AbstractA single‐pass total internal reflection (TIR) Raman technique for studying the stretching modes of water close to Langmuir–Blodgett (LB) films of amphiphilic molecules is described. The method is based on efficient collection of the 458 nm (argon ion laser) excited Raman scattering from water layers adjacent to a sapphire prism coated with LB films. The experimental arrangement permitted comparison between scattering from vicinal water and that from bulk water. Polarized TIR Raman spectra for D2O of reasonable signal‐to‐noise ratio were obtained at moderate laser excitation powers (50–100 mW). However, the levels of parasitic scattering from the prism compromised the collection of corresponding spectra of good quality for H2O. Comparisons were made between the OD Raman band for D2O layers adjacent to the prism coated with LB films of ω‐tricosenoic acid with that for D2O near the uncoated prism. Small but well defined increases in the intensity of the low‐frequency shoulder of the OD band near 2400 cm−1 for the coated compared with the uncoated case are discussed in terms of possible structuring of the vicinal water by the hydrophobic film. Refinements to the experimental set‐up to increase further the sensitivity for probing water layers near surfaces are briefly considered.
Simple cell for microscale capillary solution and supercritical fluid Raman spectroscopy
Authors: Howdle Steven M. , Best Stephen P. 
Published: May 2005

AbstractA microscale capillary Raman solution flow cell has been developed utilizing conventional high‐performance liquid chromatographic capillary tubing. This cell is suitable for both liquids and gases over a wide range of pressures. The introduction of a liquid flow along the capillary allows the collection of Raman spectra of intensely coloured and highly absorbing solutions, e.g. I2CCl4, using 514.5 nm excitation. The application of this cell to the examination of supercritical fluids is demonstrated. The use of small cross‐section capillary tubing (ca 10−5 cm2) allows high linear flow‐rates to be maintained with comparatively small solution volumes.
Resonance Raman spectroscopic study of polypyrrole in CuZSM‐5
Authors: Blanking James R. , Millar Graeme J. , Bowmaker Graham A. , Cooney Ralph P. 
Published: May 2005

AbstractRaman spectroscopy was employed to study the polymerization of pyrrole over a selection of copper‐exhanged ZSM‐5 zeolites. No polymerization occurred on catalysts of low copper content, which suggested that a critical concentration of copper(II) cations was required for reaction. On ZSM‐5 materials with low Si/Al ratios, bands were detected which were characteristic of partially oxidized polypyrrole and monomeric pyrrole. The polymer was degraded in the presence of residual oxygen. It was shown that the polymer incorporated both aromatic‐ and quinoidal‐type structures. Further, resonance Raman spectroscopy suggested that the charge carrier present in the oxidized polymer was associated with the quinoid arrangement.
Polarized Raman and infrared studies of single crystals of orthorhombic modification of polyoxymethylene and its linear oligomer: Crystal structures and vibrational assignments
Authors: Kobayashi Masamichi , Adachi Toshihisa , Matsumoto Yoshitake , Morishita Hirofumi , Takahashi Takehito , Ute Koichi , Hatada Koichi 
Published: May 2005

AbstractIn order to make vibrational assignments of the metastable orthorhombic modification of polyoxymethylene (o‐POM), polarized Raman and infrared spectra of a single crystal of deca(oxymethylene) diacetate, CH3COO(CH2O)10COCH3 (POMAc10), a linear oligomer of POM, were measured and compared with previous results obtained using a micron‐sized single crystal of o‐POM. On the basis of the orientation of the o‐POM sublattice in the POMAc10 crystal, assignments of the zone‐centre modes of o‐POM was established and the unit cell orientation in the micron‐sized o‐POM single crystal was decided. The morphology‐dependent frequency shifts of the parallel infrared bands (B1 modes) in the POMAc10 crystal, which has a specific morphological structure different from the lamellar crystal of high‐molecular‐weight o‐POM, were investigated on the basis of the transition dipolar coupling theory.
Raman studies of intact and sodium doped 13C‐substituted poly‐p‐phenylene
Authors: Furukawa Yukio , Ohtsuka Hirofumi , Tasumi Mitsuo , Wataru Isao , Kanbara Takaki , Yamamoto Takakazu 
Published: May 2005

AbstractThe Raman and infrared spectra of 13C‐substituted poly‐p‐phenylene (PPP) and the Raman spectra of Na‐doped PPP excited at 488.0 and 1064 nm were observed and compared with the corresponding spectra for the ordinary (12C) polymer. 13C substitution is shown to be useful for characterizing not only the bands of intact PPP but also those of polarons and bipolarons generated in Na‐doped PPP. The number of Raman bands observed for bioplarons (and also for polarons) is greater than that for intact PPP. This observation is explained as the result of the loss of translational symmetry in the regions of these local excitations.
Double‐resonant Raman scattering by LO‐phonons in quantum wells in a magnetic field
Authors: Govorov A. O. 
Published: May 2005

AbstractOne‐LO‐phonon resonant Raman scattering in quantum wells in the presence of the magneto‐polaron effect was investigated theoretically. The cross‐section of Raman scattering involving uncorrelated electron–hole pairs as intermediate states was calculated using the parabolic model of valence bands. An analysis showed that the magneto‐polaron effect plays an important role in double‐resonant Raman processes. The Raman intensity under double‐resonant conditions in a magnetic field is strongly increased by α−1 times, where α is the electron–phonon coupling constant. The Fröhlich and deformation‐potential electron–phonon interactions are considered for different scattering configurations in a model of confined phonons.
Raman scattering study of (NH4)3−xRbxZnBr5 single crystal
Authors: Krylov A. S. , Schäfer A. D. , Vtyurin A. N. 
Published: May 2005

AbstractThe lattice dynamics of a recently synthesized crystal of (NH4)3−xRbxZnBr5 were studied by Raman spectroscopy. The spectra were found to be in good agreement with the crystal structure. Clear evidence of NH4 group disorder was found. Ordering of these groups at low temperatures was observed.
Micro‐Raman study of ion‐irradiated oxidized silicon surfaces
Authors: Tripathi R. , Kar S. , Bist H. D. 
Published: May 2005

AbstractMicro‐Raman studies were performed on ion‐irradiated oxidized silicon surfaces with different ion energies, ion fluences and subsequent hydrogenation to determine the efficacy and sensitivity for obtaining information on the degree of ion beam‐induced damage in very thin (ca. 100 Å) layers of silicon subsurface and the top oxide. The variations in the Raman spectra were interpreted in terms of the degree of amorphization produced in the silicon sub‐surface by the ion beam and depolymerization of the top SiO2 layer.
Broad background bands in Raman spectra of alumina studied by both visible and near‐infrared excitation
Authors: Mortensen A. , Christensen D. H. , Nielsen O. Faurskov , Pedersen E. 
Published: May 2005

AbstractRaman spectra were obtained for two different samples of alumina. One is usually used as a support for hydro‐treating catalysts in heterogeneous catalysis and the other was synthesized in the laboratory. Different excitation wavelengths were used: 457.9, 488.0, 514.5, 647.1 and 1064 nm. The commercially available alumina showed an intense broad background with excitation in the near‐infrared region, whereas no significant background was observed with visible excitation. The synthetic alumina showed a broad background band with laser excitation in the visible region. It is shown that the appearance of these backgrounds is not due to fluorescent impurities (e.g. iron, chromium or organic compounds). Tentative explanations of the spectral features are provided in terms of density of states (alumina A) or bulk hydroxyl groups (alumina B).
Infrared reflectance and Raman spectra of lithium triborate single crystal
Authors: Xiong Guisheng , Lan Guoxiang , Wang Huafu , Huang Chaoen 
Published: May 2005

AbstractInfrared reflectance and Raman spectra of LBO crystals were recorded at room temperature and liquid nitrogen temperature. The vibrational modes are classified by the factor group analysis method and the spectral bands are assigned to vibrations of the (B3O6)3− ring and BO4 tetrahedra.
Enhancement factor of surface‐enhanced Raman scattering on silver and gold surfaces upon near‐infrared excitation. Indication of an unusual strong contribution of the chemical effect
Authors: Hildebrandt Peter , Keller Stefan , Hoffmann Andreas , Vanhecke Franck , Schrader Bernhard 
Published: May 2005

AbstractSurface‐enhanced Raman (SER) spectra of the xanthine dyes rhodamine 6G (R6G) and oxazine 1 (OX1) were measured with near‐infrared excitation employing Fourier transform Raman spectroscopy. Both dyes exhibit strong SER signals on Ag and Au surfaces. The enhancement factors were evaluated based on the determination of the number of adsorbed molecules. In the absence of additional electrolyte, the enhancement factors for R6G on Ag and Au sols are 1.3 × 104 and 1.6 × 104, respectively. This enhancement is operative for all adsorption sites and is ascribed to the classical electromagnetic mechanism. On activation of the Ag sol by chloride ions, the enhancement factors for R6G and OX1 are 4.3 × 107 and 7.6 × 105, respectively. This increased enhancement which occurs at a small number of specific adsorption sites is ascribed to the charge‐transfer mechanism. For R6G this enhancement mechanism is stronger by a factor of 47 than for visible excitation. The electrolyte‐induced activation is not possible for Au sols or precipitates of Ag or Au on filter‐papers. These metal‐coated filter‐papers may provide appropriate SER‐active surfaces for analytical applications of the SER effect in combination with Fourier transform Raman spectoscopy.
Raman scattering study of phase transitions in undoped and rare earth ion‐doped BaCeO3 and SrCeO3
Authors: Scherban T. , Villeneuve R. , Abello L. , Lucazeau G. 
Published: May 2005

AbstractPolycrystalline samples of perovskite‐structured BaCeO3 and SrCeO3 were studied by Raman scattering spectroscopy in the temperature range 77–983 K. Changes in the spectra of BaCeO3 with temperature are explained in terms of a second‐order phase transition (D2h → D4h) at T0 = 427 K. Analysis of the temperature dependence of soft modes suggests a partial displacive character. A dramatic decrease in band intensity above 1000 K indicates a transition to the cubic (Oh) structure, for which no Raman bands are expected. The Raman spectra of SrCeO3 indicate that no phase transitions occur in the temperature range 77–983 K. Room temperature spectra of BaCeO3 doped with various rare earth ions (Nd3+, Gd3+, Yb3+) are compared. Doping with 5 and 10 mol.% Nd stabilizes the high‐temperature tetragonal and cubic phases, respectively. The crystal structure is a sensitive function of Nd dopant concentration.
Photodissociation of (DMSO)2Fe(II)PPIX to form a transient five‐coordinate complex as studied using transient resonance Raman spectroscopy
Authors: Nalliah R. E. , Findsen E. W. 
Published: May 2005

AbstractResonance Raman spectra of iron(II) protoprophyrin IX [Fe(II)PP] in dimethyl sulfoxide (DMSO) and deuterated DMSO were obtained at high and low photon densities using 10 ns laser pulses. At low photon density, comparison of the Raman spectra of the complex with those of carbonmonoxy‐hemoglobin indicates that a low‐spin, six‐coordinate (DMSO)2Fe(II)PP complex exists; at high photon density, spectral comparisons with deoxyhemoglobin and the 2‐methylimidazole heme complex (2‐MeIm)Fe(II)PP indicate that a transient high‐spin, five‐coordinate complex is formed by photodissociation of a DMSO ligand. This phenomenon is reversible and observable on a 10 ns time‐scale.
Raman spectra of piperazine hexahydrate and N–D stretches by polarons
Authors: Kanesaka Isao , Kuwano Kazuhiko , Ishioka Tsutomu 
Published: May 2005

AbstractThe Raman spectrum of deuterated piperazine hexahydrate shows a new band that is red shifted from the main ND stretch by 38 cm−1. The intensity of this band increases at low temperatures. It is proposed that this band arises from polarons. Although the corresponding new band is not resolved in the NH stretch region of the hydrogenated system, the band width increases on cooling, which suggests the appearance of a new band due to polarons. The less resolved spectral feature in the hydrogenated system is discussed.
Nafion‐supported metal complexes: a resonance Raman and UV–visible spectroscopic study
Authors: Maclean Angela L. , Armstrong Robert S. , Kennedy Brendan J. 
Published: May 2005

AbstractResonance Raman and UV–visible spectra of cobalt tetraphenylporphyrin and cobalt phthalocyanine in Nafion were recorded. The spectroscopic measurements show that the porphyrin is incorporated into the hydrophobic regions of the polymer whilst the phthalocyanine is associated with the ionic domains. The macrocycles undergo a change in geometry in Nafion, the porphyrins exhibiting a decreased core size in the membrane.