bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman spectroscopy of oxygenated amorphous CdTe films
Authors: Morell G. , Reynés‐Figueroa A. , Katiyar R. S. , Farías Mario H. , Espinoza‐Beltran F. J. , Zelaya‐Angel O. , Sánchez‐Sinencio F. 
Published: May 2005

AbstractOxygenated CdTe films prepared by r.f. sputtering have been shown to have band gap energies between 1.48 and 3.35 eV, depending on the amount of oxygen incorporated in the CdTe matrix. Samples with oxygen concentrations above 7 at.% are amorphous, whereas those with oxygen concentrations below 7 at.% are polycrystalline, as determined by x‐ray and Raman measurements. The Raman spectra of the polycrystalline samples show that there is ca. 4 at.% Te in the form of inclusions under high pressure, which is relatively easy to detect owing to the enhanced Raman cross‐section of Te. The Raman spectra of the amorphous samples is dominated by a single broad band at 159 cm −1. The fact that tellurates in general show a similar band, in spite of their different vibrational density of states, indicates that it corresponds to TeTe bonds in the amorphous matrix.
Infrared and Raman selection rules in diperiodic three‐dimensional layers
Authors: Burneau A. 
Published: May 2005

AbstractDiperiodic three‐dimensional layers are distributed among 31 orientation classes and 80 plane groups of which 43 are symmorphic. The site symmetries of these diperiodic plane groups are tabulated. Examples of applications illustrate the determination of the first‐order selection rules for the long‐wavelength normal modes of a layer. The symmetry species of these principal modes are obtained, as in triperiodic crystals, through correlations between the reduced representation of the factor group of the layer diperiodic group and the representations of nuclear site groups, on the basis of atomic motions. Emphasis is placed on the splitting of the layer modes in a layered crystal. A procedure is described to relate a typical, quasi‐isolated layer to the real sample through a real layer in the sample, whose diperiodic group is a subgroup of both space groups corresponding to the preceding structures. The method is similar to the molecular site group analysis and provides directly, for a specific type of layer motion, the correlations between equivalent layers. The quasi‐isolated layer approximation is used to study the principal vibrations of graphite intercalation compounds and of anisotropic crystal polytypes with more than one layer per unit cell.
Raman scattering in ferroelectric (CH3NH3)3Bi2Br9 single crystals
Authors: Miniewicz A. , Jakubas R. , Ecolivet C. , Girard A. 
Published: May 2005

AbstractThe Raman spectra of ferroelectric (CH3NH3)3Bi2Br9 single crystals were studied at temperatures from 80 to 300 K and in the wavenumber range 0–300 cm−1. A tentative assignment of the observed bands is proposed. The phase transitions reported at 188, 140 and 101.5 K influence the Raman spectra and the observed changes are discussed in terms of the possible mechanisms involved. The lowest phase transition at 101.5 K is directly connected with instability of the inorganic sublattice.
Molecular relaxation in dimethyldichlorosilane from Raman band shape studies
Authors: Iliescu T. , Bratu I. , Grecu R. , Veres T. , Maniu D. 
Published: May 2005

AbstractRotational and vibrational relaxation of pure liquid dimethyldichlorosilane (DMDCS) at temperatures of 279, 293, 308 and 323 K and in carbon tetrachloride, dioxane, chloroform and cyclohexane solutions at 293 K were studied by Raman band shape analysis. The activation energy for molecular reorientation of DMDCS molecules was determined. The experimental vibrational correlation functions were compared with the Kubo‐Rothschild and Oxtoby relationships.
High‐resolution stimulated Raman spectrum of ethane (12C2H6) in the region of the CH symmetric stretching
Authors: Abad L. , Bermejo D. , Cancio P. , Domingo C. , Herrero V. J. , Santos J. , Tanarro I. , Montero S. 
Published: May 2005

AbstractThe high‐resolution (ca. 0.008 cm−1) stimulated Raman spectrum of the strongly perturbed CH symmetric stretching region of 12C2H6 at room temperature and at a rotational temperature of ca. 30 K, achieved in a free supersonic jet expansion chamber, is reported. The spectrum is tentatively analysed and assigned in terms of a simplified vibration‐torsion–rotation Hamiltonian. Besides the already known strong Fermi resonance, several Coriolis torsional interactions are identified as the major perturbations in this spectral region.
Vibrational dephasing times of bis(dimethylamino)heptamethine iodide determined by CARS using incoherent light
Authors: Lau A. , Kummrow A. , Pfeiffer M. , Woggon S. 
Published: May 2005

AbstractInterferometric coherent anti‐Stokes Raman scattering (ICARS) using incoherent laser light was used for time‐resolved measurements of vibrational parameters of solutions of bis(dimethylamino)heptamethine iodide in the ground and the S1, state. The vibrations at 1124, 1195, 1285 and 1304 cm−1 have dephasing times in the range 0.3–1.1 ps. The shortest dephasing time is observed for the normal mode at 1195 cm−1 with a large amplitude for the N atoms. The coherence peak in the ICARS signal around zero delay is broadened due to coupling to the electronic transition. The same peak width of 80 fs is found using degenerate four‐wave mixing.
Fourier transform Raman study of acid—base interactions via guanosine N‐7 in solid complexes and in strongly acidic solutions
Authors: Bertoluzza A. , Fini G. , Tosi M. R. , Tugnoli V. 
Published: May 2005

AbstractAmong the nucleosides, guanosine shows an anomalous behaviour which has been related to various factors (conformation, H‐bonding, self‐association, etc.), which characterize this nucleoside in relation to the others. It also easily forms a gel, the structure of which is well known. This work concerns the Raman vibrational spectroscopic characterization of the reactivity of guanosine N‐7, which is one of the main factors responsible for the anomalous behaviour of guanosine. For this purpose, some of its acid–base solid complexes and strongly acidic aqueous solutions were studied. In particular, this study considers the two Raman bands at about 1480 and 1540 cm−1, attributable to vibration modes with prevailing imidazolic character, N‐7 of free guanosine or bonded guanosine, respectively. In addition, the acid–base interaction via the H‐bond of N‐7 and the proton transfer in relation to the ΔpKa. of the interacting group were studied.
Structure, intermolecular interactions and molecular mobility in aqueous solutions of decylammonium chloride
Authors: Ferrari G. , Zerbi G. 
Published: May 2005

AbstractThe temperature‐dependent vibrational infrared and Raman spectra of 20% solutions of decylammonium chloride in H2O (D2O) were studied. According to previous work, phases SI and SII were identified in the low‐temperature range. Molecular and supermolecular structures were derived. The upper shift (Δν = 12 cm−1) of the Raman‐active antisymmetric stretching CH2 mode (d−) and its narrowness are peculiar and specific signals of a specific structure. It is proposed that the phase transition SI → SII is originated by the onset of a conformational flexibility generally described as twistons or conformational solitons. No evidence was found that the alkyl residues have librational freedom about their axes.
Pre‐resonance Raman effect of some croconates in the solid state
Authors: Gonçalves Norberto Sanches , Shamir Jacob , Santos Paulo Sergio 
Published: May 2005

AbstractThe optical and Raman spectra of several salts of croconic acid were investigated in order to obtain a better understanding of solid‐state effects. The results indicate that for the sodium and barium salts the perturbations can be ascribed to a decrease in the local symmetry of the anion. On the other hand, for the thallium and silver salts the perturbations are much more dramatic, clearly indicating the presence of charge‐transfer effects. For the silver salt, the abnormal enhancement in the Raman spectrum is ascribed to the presence of silver microparticles in the surface of the solid.
Low‐temperature order–disorder phase transition of PLZT x: 95:5 ceramics, with La Content x = 0.5–4% by weight, determined by Raman spectroscopy
Authors: El‐Harrad I. , Carabatos‐Nédelec C. , Handerek J. , Ujma Z. , Dmytrow D. 
Published: May 2005

AbstractInvestigations of the Raman spectra of lead–lanthanum–zirconate‐titanates (PLZT) x:95:5 (x = 0.5, 1, 2, 3 and 4 wt.% La2O3) ceramics over a range of temperature from 10 K to room temperature are presented. With increasing temperature the intensity of the Raman spectra, corrected for the Bose population factor, is lower above the transition temperature T0 = 130 K; this intensity lowering is characteristic of disorder‐induced spectra. This temperature dependence is interpreted by means of the theory of fluctuating clusters in the low‐temperature phase and the order parameter below T0 was determined. Associated with this phase transition, it was found that some softening effects are present in the vibrational wavenumbers.
Micro‐Raman spectroscopic study of organ cultured corneae
Authors: Siew Diana C. W. , Clover Gillian M. , Cooney Ralph P. , Wiggins Phillipa M. 
Published: May 2005

AbstractRaman spectroscopy of water was used to assess the metabolic state of fresh corneae and those which had been stored under long‐term organ culture conditions. Both human and porcine tissue were employed. The data showed a semi‐quantitative relationship between corneal hydration (determined using wet and dry weights of the tissue) and the integrated intensity of the water to collagen bands in the spectral region 2700—4000 cm−1. Variables included duration of storage, composition of culture medium and, for the human specimens, the age of the cornea. Raman assessment of hydration may provide a better measure of the functional state of the stored cornea that the density of live endothelial cells, which is a commonly used criterion. The spectra showed that the healthy cornea of low water content contained more weakly hydrogen‐bonded water than either bulk water or a swollen cornea. This is to be expected as groups on proteins and proteoglycans in the cornea form weak bonds with water. These weakly bonded surface groups are diluted when water is imbibed, hence resulting in the spectrum becoming more like that of bulk water in swollen tissue. Addition to the culture medium of dextran, which osmotically thins the cornea, converted its water spectrum back towards that of a healthy cornea.
Resonance Raman and infrared studies of the organic superconductor k‐(MDT‐TTF)2AuI2 in the normal state
Authors: Zambounis J. S. , Patsis A. P. , Kamitsos E. I. , Mayer C. W. , Papavassiliou G. C. 
Published: May 2005

AbstractResonance Raman and infrared spectra of the organic superconductor K‐(MDT‐TTF)2AuI2 were measured to identify the vibrational modes which exhibit strong electron—molecular vibration (EMV) coupling. Excitation wave‐length dependence of certain Raman modes was observed and is discussed in connection with the UV—visible absorption spectrum. Raman spectra measured at 77 K revealed a significant enhancement of a low‐wavenumber mode attributed to the organic part, while the symmetric AuI2− anion was found to be unaffected at low temperatures.
Raman and infrared spectra, conformational stability, vibrational assignment and ab initio calculations of methyl cyanoformate
Authors: Durig J. R. , Groner P. , Drew A. S. , Guirgis Gamil A. , van der Veken B. J. 
Published: May 2005

AbstractThe Raman (3100–10 cm−1) spectra of the liquid and solid and the infrared (3100—400 cm− 1) spectra of the gas and solid were recorded for three isotopic species of methyl cyanoformate, 12CH3OCOCN, 13CH3OCOCN and CH318OCOCN. Additionally, the far‐infrared (370—60 cm− 1) spectrum of the gas of the normal species was recorded. Raman depolarization ratios were obtained for the liquid phases of all three isotopic species. These data were interpreted on the basis that the only stable conformation present at ambient temperature is the s‐trans rotamer where the methyl group is trans to the cyano group. As predicted by ab initio calculations using the MP2/6—31G* basis set, the infrared intensity of the methyl torsion is very weak and, subsequently, this fundamental is not observed in the far‐infrared spectrum of the gas. Therefore, an experimental barrier to internal rotation for the methyl group could not be obtained from the vibrational data. However, the theoretical barrier to internal rotation was calculated to be 424 cm− 1 (1.21 kcal mol− 1) using the RHF/6—31G* basis set. The structure, infrared intensities, Raman activities and vibrational wavenumbers for the s‐trans conformer were also determined from ab initio calculations using the RHF/3—21G, RHF/6—31G* and MP2/6—31G* basis sets. These results are compared with those obtained experimentally and with similar quantities for some related molecules.
Infrared and Raman spectra of crystallization water in potassium N, N‐dimethyloxathioamidate monohydrate
Authors: Desseyn H. O. , Hereygers M. L. B. F. , Perlepes S. P. 
Published: May 2005

AbstractRaman and infrared measurements were performed on hydrated (H2O and D2O) and anhydrous (CH3)2NCSCOOK together with their CD3‐substituted analogues. Close scrutiny of the water fundamentals indicated that the C2v symmetry of the single water molecule is lost owing to different strengths of hydrogen bonding with the carboxylate and thioamide functional groups. The number of water fundamentals and the wavenumber and intensity changes at different temperatures are, considering the very complex structure of the water spectra, unexpectedly consistent with the predictions of a single asymmetric water molecule.
Vibrational contribution to the internal rotation potential of toluene and nitromethane
Authors: Grošev Vlasta Mohaček , Schrötter Heinz W. , Jonuscheit Joachim 
Published: May 2005

AbstractThe vibrational contribution to the internal rotation potential of toluene and nitromethane is calculated for different force fields which were constructed using permutation‐inversion group and dependent on the internal rotation angle. The assignments of Raman spectra were made using experimental data obtained for the liquid and vapour (toluene) states and supported by vibrational analysis calculation. The vibrational contribution calculated with a ρ‐independent force field represents the kinetic energy contribution to the internal rotation potential of the molecule in question. For toluene (C6H5CH3) and nitromethane (CH3NO2) the kinetic energy contribution is zero, and for C6D5CHD2 and CHD2NO2 it has a cos (2ρ) dependence. This sort of calculation may serve as a check of any force field used for assigning molecular vibrations by comparing calculated internal rotation potentials in excited vibrational states with the parameters of the potential found from the fit of vapour band contours.
End‐chain conformations of n‐alkane molecules in urea inclusion compounds: A Raman scattering study
Authors: Baghdadi Abdelkrim El , Guillaume François 
Published: May 2005

AbstractUrea inclusion compounds containing n‐alkane (CnH2n+2 with n = 8 and 19) guest molecules were investigated by means of Raman spectroscopy. Vibrational modes due to the urea confirm the structural identify of the inclusion compounds, and lattice modes of the urea host structure were assigned tentatively. Investigations of the vibrational properties of the CnH2n+2 guest molecules were focused on the longitudinal accordion mode (LAM‐1) and the methyl rocking r(CH3) vibrations. These modes were studied as a function of (i) the length (n) of the guest molecule, (ii) temperature and (iii) pressure. The vibrational bands characteristic of the end‐gauche gt‐ and tg‐defects were therefore identified. From these results, trends in the relative amounts of gauche gt‐ end‐groups for the various guest molecules were assessed in both the low‐ and high‐temperature structural phases of the compounds and found to be constant and of the order of ca. 5%. It was also shown that the amount of n‐alkane chains distorted at their ends depends markedly on the hydrostatic pressure. These results are discussed and compared with literature data.
Method for the determination of spectral shifts in Raman spectroscopy
Authors: Gaufrès Robert , Huguet Patrice , Arab Youssef 
Published: May 2005

AbstractA new method for the determination of the wavenumber shift between two bands was developed. It rests on the mathematical properties of the absolute area of a difference spectrum, previously proved by the authors. Its field of application is wider than that of the method used up to now, as it allows the determination of the shift between two bands of any profile, provided that the profiles of these bands are identical, and between bands of different profiles, provided that they are symmetrical. No approximation, unless completely justified, is involved in this method. It is exemplified by some experiments which demonstrate its accuracy. A final experiment shows the possibility of determining a Raman shift between two liquid samples using a classical device, with fair accuracy.
Analysis of polarized Raman spectra of liquids at liquid—solid interfaces
Authors: Bousquet C. , Masson M. , Harrand M. 
Published: May 2005

AbstractPolarized Raman spectra of liquids within a solid—liquid interface were analysed. The liquid, deposited on the solid surface, is illuminated by an evanescent electromagnetic wave; the penetration depth is l ≤ 100 nm. Interface liquid spectra are compared with the polarized spectra of the isotropic liquid. It is found that the changes observed in the spectra cannot be explained merely by structural changes in the molecules; the influence of changes in the main characteristics of the exciting electric field, arising from defects of the solid surface, must also be considered. With rutile surfaces, the experimental spectra are linear combinations of the isotropic liquid spectra; the electric field, partially depolarized by the surface defects, is still a long‐range field: no structural changes for the molecules are found within the illuminated part of the interface. With thin silver film‐coated surfaces, however, the spectra cannot be reduced to linear combinations of the liquid spectra. Structural changes for the molecules are also involved. The electric field is enhanced by the excitation of the surface plasmon of silver but, because of the surface defects, the field, partially depolarized, spreads over a range much shorter than l, and is strongly dependent on the defect geometry. The short‐range enhancement can mask a possible further orientation of the molecules, preventing any determination of the range of the solid—liquid interaction. Time dependence of the spectra related to an increase in the silver surface roughness leads to surface‐enhanced Raman scattering (SERS).
Raman spectroscopic studies of α‐NaVO3, β‐NaVO3 and NaVO3 · 2H2O
Authors: Kuok M. H. , Tang S. H. , Shen Z. X. , Ong C. W. 
Published: May 2005

AbstractSodium metavanadates in α (α‐NaVO3), β (β‐NaVO3) and hydrated (NaVO3 · 2H2O) forms were studied down to 10 K. All the phases were found to be stable at low temperatures. The hydrated to β transformation above room temperature was found to occur at 305 K. This transition is first order and most likely a one‐step process, rather than a two‐step process as had been suggested previously.
Accurate relative calibration of a multi‐channel Raman spectrometer
Authors: Huguet Patrice , Gaufrès Robert 
Published: May 2005

AbstractA method of restoring a given spectral position of a multi‐channel Raman spectrometer is described. With a spectrometer, the wavenumber counter of which is graduated in cm−1 and the dispersion on the detector is about 0.7—0.9 cm−1 per photodiode, the standard deviation about a mean position is shown to be 0.15 cm−1 when this method is used.
Depolarized rayleigh wing from Raman spectra and local order in pure C6H6 and C6F6 liquids and in their binary mixtures
Authors: Dayan E. , Loisel J. , Berreby L. , Dervil E. , Pinan‐Lucarré J. P. 
Published: May 2005

AbstractFrom Raman spectra, the low‐wavenumber range profile (10‐200 cm−1) of planar molecules C6H6, C6F6 and of their binary mixtures in the liquid state was recorded at intervals of 1°C from 10 to 65°C. The analysis was made using a reduced intensity ratio R involving the integrated intensity of a constructed I(v)v2 spectrum and the recorded I(v) spectrum. The study of R against a slow and gradual variation of temperature emphasized a break in the gradient for pure liquids. This effect is related to a change in the local environment of the molecules. This break did not appear in the study of a 1:1 mixture owing to its strong stability due to a face‐to‐face configuration.
SERS and SERS of Langmuir—Blodgett monolayers: Surface coverage dependence at room and low temperature
Authors: Menéndez J. R. , Martin Fernando 
Published: May 2005

AbstractSERRS intensity patterns versus surface molecular coverage, both at room temperature and at low temperature (liquid N2), were studied using mixed Langmuit‐Blodgett (LB) monolayers of tetra‐tert‐butylvanadyl‐phthalocyanine and lutetium bisphthalocyanine with arachidic acid. The role played by temperature variations in the surface coverage dependence and SERRS intensity patterns is analysed.
Raman spectroscopy of bismuth tungstates
Authors: Hardcastle Franklin D. , Wachs Israel E. 
Published: May 2005

AbstractThe Bi2O3‐WO3 system was examined using Raman spectroscopy. The Raman spectra of bismuth tungstate samples having Bi: W ratios of 2:1, 4:1 and 14:1 were used to identify the bismuth tungstate phases present at these compositions. The bismuth tungstate phases which occur were found to depend on the Bi: W ratio. The 2:1 composition consists of only the Bi2WO6 phase and the 14:1 composition consists almost entirely of the sillenite phase. The 4:1 composition, however, is multi‐phase and consists of Bi2WO6, the sillenite phase, and another phase referred to as 7Bi2O3‐2WO3. The Raman spectra were used to determine the coordination of the tungstate species as well as their WO bond lengths in each of these phases.
Study of β‐carotene by time and wavenumber domain coherent anti‐stokes Raman scattering techniques
Authors: Kummrow Andreas , Lau Albrecht 
Published: May 2005

AbstractDephasing of vibrations of all‐trans‐β‐carotene in cyclohexane was studied by resonance CARS in the wavenumber domain, using scanning CARS, and also in the time domain, by interferometric CARS (I‐CARS) applying temporally incoherent light from non‐transform limited broadband lasers. The ground‐state vibrations (1002, 1153, 1188, 1210 and 1522 cm−1) are predominantly homogeneously broadened and have dephasing times ranging from 0.6 to 0.7 ps. For broadband wavenumbers in the long‐wavelength wing of the absorption band and a Stokes laser intensity exceeding 0.5 GW cm−2, the CARS signal saturates and decreases above 1 GW cm−2. The decrease in the CARS signal is accompanied by the appearance of additional Raman lines. Taking into account all these Raman lines (solvent lines and two additional very broad lines), the features of the I‐CARS can be explained with the same parameters as for scanning CARS. Consideration of these additional lines is essential. Using excitation wavenumbers within the absorption band, power broadening of the 1522 cm−1 line is observed. In some experiments, diffraction by a laser‐induced grating strongly competes with I‐CARS.