bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface‐induced substitution reaction on cobalt(III) and manganese(III) tetrakis (4‐N‐methylpyridyl)porphyrins probed by surface‐enhanced Raman spectroscopy
Authors: Ha Jong‐Seo , Song Ok‐Keun , Yoon Minjoong , Kim Dongho 
Published: May 2005

AbstractThe Surface‐enhanced Raman spectra of Co(III)TMPyP(4)Cl and Mn(III)TMPyP(4)Cl [where TMPyP(4) = tetrakis (4‐N‐methylpyridyl)porphyrin] demonstrate the formation of Ag(II)TMPyP(4) on the silver surface. The reaction is not photon assisted but is dependent on the sol activity and time. The effect of NaCl on the sol activity and the surface‐induced reaction was investigated. It was observed that the metal substitution reaction of Mn(III)TMPyP(4)Cl was more efficient than that of Co(III)TMPyP(4)Cl.
Determination of molybdenum–oxygen bond distances and bond orders by Raman spectroscopy
Authors: Hardcastle Franklin D. , Wachs Israel E. 
Published: May 2005

AbstractA correlation is developed for relating Raman stretching frequencies of molybdenum–oxygen (MoO) bonds to their respective bond distances in molybdenum oxide compounds. MoO bond orders are also related to stretching frequencies. The MoO correlation is expected to offer invaluable insight into the structures of molybdate species in chemical systems which are not amenable to analysis by diffraction or other spectroscopic techniques. In the present study, the correlation is used to predict stretching frequencies for perfect MoO4 and MoO6 structures, and to determine MoO bond distances of the MoO6 octahedron in Ba2CaMoO6 as well as the dehydrated surface molybdate species in MoO3/Al2O3.
The MCGA (multiple cubic gradient approximation) method for the analysis of Raman spectra
Authors: de Mul F. F. M. , ten Have H. B. G. , Otto C. , Greve J. 
Published: May 2005

AbstractAn easily accessible interactive method for the analysis of Raman spectra consisting of many overlapping peaks is presented. A combination of a three‐ or four‐dimensional grid and gradient searching is applied. The method can handle spectra with up to about 50 lines, based on a broad background. Analytical and user‐defined or tabulated basic functions can be included. The merits of the method are discussed with both artificial and real spectra.
Preresonance Raman spectra of methylpyridines
Authors: Kosmidis C. , Bolovinos A. , Tsekeris P. 
Published: May 2005

AbstractPreresonance Raman spectra of methylpyridines (picolines) are presented for different incident laser wavelengths. A strong intensity variation of the non‐totally symmetric vibration 10α is observed, which implies a vibronic coupling of the lowest nπ* excited state with the next ππ* (B2u and B1u) states. In addition an intensity increase of some totally symmetric vibrations is observed and their possible implications for the geometry of the excited ππ* states are discussed.
IR and polarized Raman spectra of KIO3 · Te(OH)6
Authors: Santha N. , Nayar V. U. 
Published: May 2005

AbstractThe IR and polarized Raman spectra of the addition compound KIO3 · Te(OH)6 were recorded and analysed. Bands indicate that the IO3− ion is distorted in this crystal and its symmetry is less than its free ion symmetry, C3ν. The TeO6 ion occupies a lower symmetry, C1, than its free ion symmetry, Oh.
High‐resolution non‐linear Raman spectroscopy in gases
Authors: Schrötter H. W. , Berger H. , Boquillon J. P. , Lavorel B. , Millot G. 
Published: May 2005

AbstractThe resolution in the Raman spectra of gases has been greatly improved by the development of the different methods of non‐linear Raman scattering. When two laser beams, one of which has a tunable frequency, are focused in a sample, a stimulated Raman process occurs as soon as the frequency difference between the two lasers is equal to a Raman‐active rovibrational or rotational transition frequency. The Raman resonance can be detected in different ways: by coherent anti‐Stokes Raman scattering (CARS) or the corresponding Stokes process (CSRS), by a gain in one of the beams (stimulated Raman gain spectroscopy, SRGS) or a loss in the other (inverse Raman spectroscopy, IRS), or even by detection of a photoacoustic signal (photoacoustic Raman spectroscopy, PARS). The selective ionization of the excited molecules by a third ultraviolet laser (ionization‐detected stimulated Raman scattering, IDSRS) has considerably increased the sensitivity in special cases.The instrumental resolution is determined by the convoluted line widths of the lasers used for excitation. The narrowest line widths can be achieved with stabilized continuous‐wave lasers. Their relatively low power has been compensated for either by intracavity excitation of CARS spectra or by injection locking of dye laser amplifiers which are pumped by pulsed lasers or by flashlamps. Examples of investigations of the structure of rovibrational bands and of line‐width measurements as a function of pressure are reviewed.
Measurments of collisional line widths in the stimulated Raman Q‐branch of the ν1 band of silane
Authors: Millot G. , Boutahar A. , Lavorel B. , Wenger C. , Saint‐Loup R. , Berger H. 
Published: May 2005

AbstractSelf‐broadened widths of 28SiH4 in the ν1 Q‐branch have been measured at room temperature (295 K) using high‐resolution stimulated Raman Spectroscopy. These collisional widths have been obtained by fitting a super‐position of Voigt profiles to the experimental spectra in the pressure range 28–154 Torr. No evidence for line mixing within the tetrahedral components of a Q(J) line has been found. The line broadening coefficients for J up to 13 depend weakly on the rotational quantum number. The mean value is 103.7 × 10−3 cm−1 atm−1.
Raman spectroscopy of coexisting phases in TbP5O14
Authors: Chen Ting , Scott J. F. 
Published: May 2005

AbstractAt temperatures above the monoclinic‐orthorhombic P21/c‐Pcmn phase transition at 180°C in terbium pentaphosphate, the presence of a third phase was observed spectroscopically, identified as a C2/c monoclinic structure. Two lines at 12 and 17 cm−1 were observed to grow in intensity as the temperature was raised from 180 to 240°C; they would be described as acoustic modes at the Brillouin zone boundary in the Pcmn phase, made Raman‐active by the doubling of the unit cell along the c‐axis in the C2/c phase. The interpretation of these lines resolves a question concerning the asymmetry (‘shoulder’) of the soft optic mode at the P21/c‐Pcmn ferroelastic transition raised long ago.
Etude en Microspectrometrie Raman de l'Efficacite de Detection en Fonction de l'Epaisseur des Echantillons: Determination de la Profondeur de Champ et Consequences pour le Couplage avec un Microscope Electronique en Transmission
Authors: Dhamelincourt P. , Delhaye M. , Truchet M. , da Silva E. 
Published: May 2005

AbstractLa faisabilité du couplage d'une sonde Raman avec une microsonde de Castaing ou un microscope électronique à transmission a été étudiée dès 1986. Dans ce dernier cas, l'épaisseur d'échantillon est très faible et une série de tests a été effectuée sur un matériau modèle, le polystyrène, afin de déterminer expérimentalement la profondeur de champ, ou résolution axiale, d'un microspectrométre Raman à détection multicanale utilisé dans les conditions d'éclairement de l'échantillon et de collection de la lumière diffusée aussi proches que possible de celles correspondant au systéme Raman implanté dans le microscope électronique. Les résultats obtenus montrent que la résolution axiale observée est de l'ordre de 2 μm et qu'un spectre Raman non résonnant de bonne qualité est encore obtenu pour une épaisseur d'échantillon de 50 nm et une résolution latérale de 0.7 μm soit 2 × 10−14 g de matériau analysé. Par des traitements numériques bien connus des signaux, il parait possible d'effectuer des mesures jusqu'à des épaisseurs de 10 nm.
Multimode analysis of depolarization ratio dispersion and excitation profiles of seven Raman fundamentals from the haeme group in ferrocytochrome c
Authors: Schweitzer‐Stenner Reinhard , Bobinger Ulrich , Dreybrodt Wolfgang 
Published: May 2005

AbstractExperimental data for depolarization ratio dispersion (DPD) and resonance excitation profiles (REPs) with high spectral resolution (20 cm−1) are provided for seven Raman fundamentals in the region between 1150 and 1650 cm−1 of the haeme spectrum from ferrocytochrome c. They cover the resonant region of the Q‐band and the preresonant region of the B‐band. A self‐consistent analysis of the depolarization ratio dispersion (DPD) and resonance excitation profiles (REPs) of these Raman lines is carried out by explicit consideration of multimode mixing. This is achieved by first formulating the Raman tensor in Loudon's formulation to fifth order for each mode, thus restricting the contribution of the fifth‐order term to the vibration itself and omitting multimode contributions. By fitting this expression to the DPDs and REPs of each Raman mode, one obtains coupling parameters which in the next step are inserted into the fifth‐order term of each mode. Thus one takes account of their contributions to multimode mixing. To account for contributions of lower frequency modes, an effective ‘helping rest mode’ was added to the multimode contributions. This procedure yields satisfactory fits to all data sets. The respective fits to the DPD and REP of the oxidation marker line at 1363 cm−1 reproduce also the corresponding REP and DPD in the resonant region of the B‐band reported by Champion and Albrecht with a high degree of accuracy. The vibronic coupling parameters obtained are consistent with the weak coupling limit. Further, they confirm the validity of Gouterman's four‐orbital model for ferrocytochrome c.
Determination of aromatic composition of fuels by laser Raman spectroscopy
Authors: Clarke R. H. , Chung W. M. , Wang Q. , DeJesus S. , Sezerman U. 
Published: May 2005

AbstractThe application of Raman spectroscopy to the determination of the aromatic content of gasolines and aviation fuels is reported. Since aromatic components have very high Raman cross‐sections owing to large polarizability changes under laser excitation, bands from these components will dominate specific Raman spectral regions. It is expected, therefore, that Raman scattering will be a particularly useful approach to broadly characterizing the fuel hydrocarbon makeup for aromatic content and the properties of fuels which are influenced by aromatic content.
Raman and infrared spectra, conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment of dichloroacetyl fluoride
Authors: Durig J. R. , Bergana M. Mamula , Phan H. V. 
Published: May 2005

AbstractThe Raman spectra (3200‐10 cm−1) of dichloroacetyl fluoride (CHCL2CFO) of the gas, liquid (with qualitative depolarization ratios) and solid were recorded. The infrared spectra (3200‐30 cm−1) of the gas and solid were also obtained. All of these data indicate a trans/gauche equilibrium in the gas and liquid whereas only the gauche conformation remains in the solid. A complete vibrational assignment is proposed for both conformers based on the Raman depolarization data, infrared band contours, group frequencies and normal coordinate calculations. From the studies of the Raman spectra at various temperatures, the enthalpy difference between the stable conformers was determined to be 315 ± 68 cm−1 (0.90 ± 0.19 kcal mol−1) (1 kcal = 4.184 kJ) and 180 ± 4 cm−1 (0.51 ± 0.01 kcal mol−1) for the gas and liquid, respectively, with the trans conformer being more stable in the gas but the gauche conformer more stable in the liquid. These experimental results are compared to those obtained from ab initio Hartree‐Fock gradient calculations with the RHF/3‐21G* and RHF/6‐31G* basis sets, and to the corresponding quantities obtained for some similar molecules.
Silver colloid surface Raman spectra of phenylpropanolamine and its derivative
Authors: Li Ying‐Sing , Lee Arthur S. , Wang Yu 
Published: May 2005

AbstractThe silver colloid surface‐enhanced Raman scattering (SERS) spectrum of phenylpropanolamine (PPA) and the surface‐enhanced resonance Raman scattering (SERRS) spectrum of the PPA‐ninhydrin reaction product were studied. It was found that the spectral intensity varied with time, and the rate of the variation was related to the PPA concentration. From scanning electron microscopic photographs taken at different times, the SERS intensity appeared to be correlated with the coagulation of silver particles. Temperature was found to be another factor that would change the kinetic rate of the coagulation. Addition of potassium chloride served effectively to activate the surface‐enhanced effect and to reduce the time required to reach maximum intensity. The rate of activation was found to be dependent on the concentration.
Raman spectrum of Sr0.61Ba0.39Nb2O6
Authors: Wilde Richard E. 
Published: May 2005

AbstractThe Raman spectra of a single crystal of strontium barium niobate were recorded in the temperature range–193 to 140°C. The configurations studied were X(ZZ)Y, X(YZ)Y, X(YX)Y, Z(XX)Y, Z(YZ)Y and Z(XZ)Y. The behavior of integrated reduced intensities, band widths and band centers with temperature indicated that the ferro‐electric transition temperature was near 65°C. The Raman data were not consistent with a classical Landau transition. Disorder‐induced first‐order spectra were observed and attributed to the disordered nature of the crystal Evidence was found for a possible phase transition near 120°C.
Raman scattering of α‐toluenethiol adsorbed on silver sol
Authors: Lee Tae Geol , Kim Kwan , Kim Myung Soo 
Published: May 2005

AbstractSurface‐enhanced Raman scattering (SERS) of α‐toluenethiol adsorbed on a silver surface has been investigated. The controversial vibrational assignment of the molecule was refined by comparing the SERS spectra with the ordinary Raman spectra of α‐toluenethiol, α‐toluenethiolate, benzyl chloride and their deuterated species. Based on the assignment and the SERS selection rule, it is proposed that α‐toluenethiol is adsorbed as a thiolate on silver via its sulphur atom with both the methylene group and benzene ring oriented approximately parallel to the metal surface.
Raman spectroscopic study on ZrO2–TiO2 using MoO3 as a molecular probe
Authors: Li Ying‐Sing , Lu Weijie , Collins W. Eugene 
Published: May 2005

AbstractThe surface interaction between ZrO2 and TiO2 in physical mixtures was studies using laser Raman spectroscopy (LRS). The characteristic peaks of ZrO2 disappeared after mixing ZrO2 and TiO2 with a loading ZrO2 of less than 25 wt.% and calcination at 773 K for 12 h. Surface polyhedrally coordinated Zr on TiO2 could not be detected by LRS. Therefore, MoO3 was used as a molecular probe to detect the nature of the interactions between ZrO2 and TiO2. The results revealed that ZrO2 could disperse on the surface of TiO2 and its interaction with TiO2 is different from that of MoO3 and TiO2.
Vibrational characterization and gas chemisorption of solid films and monolayers of dysposium and holmium bisphthalocyanines
Authors: Souto J. , Aroca R. , DeSaja J. A. 
Published: May 2005

AbstractEvaporated thin solid films and Langmuir‐Blodgett monolayers of dysprosium and holmium bisphthalocyanine complexes were prepared and characterized using Raman scattering (RS), surface‐enhanced (resonance) Raman scattering, infrared and visible absorption spectroscopy. The spectroscopic evidence for molecular organization and molecular aggregation in the films is discussed. An empirical vibrational assignment of the observed fundamentals is proposed. Spectroscopic data on chemically oxidized films and films exposed to NOx(NO2/N2O4) were collected to determine the nature of the interaction between the MPc2 molecule and the NO2.
Rotational relaxation of nitrogen in argon: Collisional broadening of Q‐branch components in coherent Raman spectra of cooled gas
Authors: Kozlov D. N. , Pykhov R. L. , Smirnov V. V. , Vereschagin K. A. , Burshtein A. I. , Storozhev A. V. 
Published: May 2005

AbstractA high‐resolution (0.003 cm−1) coherent anti‐Stokes/Stokes Raman spectrometer has been used for recording the resolved rotational structure of the Q‐branch of nitrogen in argon‐nitrogen mixtures. Spectra were obtained at pressures of 50‐760 Torr and temperatures of 295 and 140 K with the object of determining argon collisional‐broadening coefficients of nitrogen rotational lines. Semi‐classical calculations of these coefficients, employing a number of model potentials, were carried out. the experimental and theoretical data are compared and discussed.
Raman studies of structural phase transition in [NH2(CH3)2]3Sb2Cl9 (DMACA)
Authors: Miniewicz A. , Lefebvre J. , Jakubas R. 
Published: May 2005

AbstractTris(dimethylammonium) nonachlorodiantimonate (DMACA) is a ferroelectric with a transition temperature Tc = 242 K. Low‐frequency Raman spectroscopic studies were carried out on this crystal within the temperature range 100‐300 K to look for possible spectral changes resulting from the phase transition. A detailed analysis of frequencies, line widths and intensities was made through the phase transition in order to understand its nature. It follows from the analysis that pseudo‐spin‐phonon interactions of higher order are effective in this case.
Vibrational spectra and assignments of diethyl sulfide, 2‐chlorodiethyl sulfide and 2, 2′‐dichlorodiethyl sulfide
Authors: Christesen Steven D. 
Published: May 2005

AbstractRaman and infrared (IR) spectra of diethyl sulfide (CH3CH2SCH2CH3), 2‐chlorodiethyl sulfide (ClCH2CH2SCH2CH3), and 2,2′‐dichlorodiethyl sulfide (mustard gas) (ClCH2 CH2SCH2CH2Cl) were measured and their vibrational frequencies were compared to calculated frequencies reported by Sosa et al. the calculated frequencies were used to make probable assignments of the vibrational bands to normal modes of the molecules. Raman depolarization ratios for diethyl sulfide and 2‐chlorodiethyl sulfide also aided in their vibrational assignments. Good agreement of the calculated frequencies with the experimental values was found except for the CS and CCl stretching frequencies, which were consistently calculated to be lower than the experimentally found values. The experimental spectra also provide evidence for the presence of more than one stable molecular conformation in the liquid phase for each of the three sulfides. This has been observed for diethyl sulfide in previous studies.
Surface‐enhanced near‐infrared fourier transform Raman scattering of tetrathiafulvalene adsorbed on silver powder
Authors: Nie Shuming , Yu Nai‐Teng 
Published: May 2005

AbstractThis report describes the use of an efficient and convenient silver substrate in the development of surface‐enhanced near‐infrared Fourier transform (FT) Raman scattering as a useful analytical technique that compliments the bulk FT‐Raman method. The SERS‐active material, prepared in the form of solid silver powder by means of chemical precipitation, is particularly well suited for surface Raman enhancement in the near‐IR region. To demonstrate the unique features of surface‐enhanced FT‐Raman, a detailed spectroscopic study of the charge‐transfer donor molecule tetrathiafulvalene (TTF) adsorbed on the silver powder is also reported. The advantages of near‐IR FT‐SERS over bulk FT‐Raman include the ability to analyze dilute solution samples, the acquisition of Raman spectra for near‐IR fluorescent compounds and new vibrational information concerning the mixed‐valence behavior of surface‐bound TTF molecules.
Raman and infrared spectra and photochemical behaviour of acetaldehyde isolated in matrices
Authors: Védova C. O. Della , Sala O. 
Published: May 2005

AbstractAs part of a general study on the behaviour of acetaldehyde as an atmospheric pollutant, the Raman and infrared spectra are presented of acetaldehyde isolated in argon and nitrogen matrices. Using the observed frequencies, the thermodynamic functions were calculated. By obtaining the vibrational spectra at low temperature, it was possible to assess the results of the photochemical studies that have been done in matrices with both argon and nitrogen gases. The main products in the photochemical decomposition of acetaldehyde under the conditions adopted are methane and carbon monoxide.
Preparation of substrates for surface‐enhanced Raman microprobe spectroscopy
Authors: Sutherland W. S. , Winefordner J. D. 
Published: May 2005

AbstractThe results obtained using a variety of new solid supports for the preparation of surface‐enhanced Raman‐active substrates via direct chemical reduction of silver salts and by vacuum vapor deposition of metallic silver are presented. These supports include two small pore size cellulose filter papers and frosted glass slides. These supports yield silver substrates with a much more uniform silver particle size and distribution than observed on previously used supports such as Whatman No. 1 and No. 5 filter papers. Results obtained using a solid silver membrane filter are also presented. These substrates provide metal particle morphology which is uniform on a submicrometer scale. This degree of uniformity is necessary for enhancing the reproducibility of SERS using a Raman microprobe since the area probed by this microprobe is 5–10 μm2. By using filter papers and glass slides, coupled with the vapor deposition and chemical reduction techniques, the resulting substrates are also fast, simple, and inexpensive, making them ideal candidates for routine analysis.
Raman spectra of Li(I), Na(I), K(I), Ba(II) and Cd(II) Salts of Uridine 5′‐monophosphoric acid
Authors: Carmona P. , Molina M. , Escobar R. 
Published: May 2005

AbstractRaman spectra were obtained for crystalline Li(I), Na(I), K(I), Ba(II) and Cd(II) salts of uridine 5′‐monophosphoric acid. Assignments were made based chiefly on a comparison of the vibrational data observed for these compounds with those of uracil and D‐ribose‐5‐phosphate and on normal coordinate calculations. Some Raman spectral features, mainly in the 1420‐1350 and 700‐600 cm−1 ranges, seem to reflect the conformational structure of the uridine residue.
Electrochemical synthesis and in situ Raman spectroscopy of thin films of titanium dioxide
Authors: Arsov Lj. D. , Kormann C. , Plieth W. 
Published: May 2005

AbstractRaman spectra of thin films of the TiO2 crystal modifications anatase and rutile are reported. The oxides are easily synthesized by electrochemical oxidation of titanium electrodes under controlled conditions. Evidence for the formation of a third crystal modification, possibly brookite, is presented.
Raman microscopy of a small uniaxial crystal: Tetragonal aspartame
Authors: Tsuboi Masamichi , Ikeda Teruki , Ueda Toyotoshi 
Published: May 2005

AbstractA general method is presented for determining the shape and orientation of the Raman tensor of a molecule in a uniaxial crystal using a Raman microscope. First, equations are derived to connect the Raman tensor components (αxx, αyy, etc.) of a molecule to the Raman tensor components (αaa, αcc, etc.) of a crystal that is composed of molecules in a uniaxial arrangement, with an orientation specified by the two angles χ and θ. Next, a method is presented to obtain a correct set of values of the intensity ratios Iac/Iaa and Icc/Iaa from observed values of the intensity ratios measured with a Raman microscope. To augment the experimental data, the depolarization ratio ρ (for a completely random molecular orientation) is plotted as a function of r1 = αxx/αzz and r2 = αyy/αzz, so that a possible set of r1 and r2 values can be found from an observed value of ρ. The method has been applied to an aspartame IIA crystal (P41). A set of values of r1, r2, χ and θ has been determined for each of the following Raman fundamentals: 1741 cm−1 (ester CO stretch), 1667 cm−1 (amide I), 1275 cm−1 (amide III) and 1204 cm−1 (CCphenyl stretch), excited at 488.0 nm.