bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automated interpretation of Fourier transform Raman spectra of complex polymers using an expert system
Authors: Claybourn M. , Luinge H. J. , Chalmers J. M. 
Published: May 2005

AbstractThe feasibility of applying an expert system for the interpretation of Raman spectra of complex acrylic and styrenated acrylic copolymers was demonstrated. The rules for the interpretation were generated automatically within the expert system from peak tables of the relevant homopolymer spectra. Application of these rules to copolymers gave excellent interpretation results without giving false negatives or false positives. Although the sensitivity limit for detection was not determined for the structural fragments characterized, components in copolymers were identified with very high probabilities down to theca. 15% (w/w) level, indicating that the lower limit is much less than this.
Relative SERS enhancement factors for pyridine adsorbed on a silver electrode. The chemical effect in SERS as a product of charge‐transfer and active‐site mechanisms
Authors: Kudelski A. , Bukowska J. , Jackowska K. 
Published: May 2005

AbstractThe relative SERS (surface‐enhanced Raman scattering) enhancement factors for pyridine adsorbed on a silver electrode were determined as a function of the laser wavelength and applied potential. The charge‐transfer (CT) effect on Raman intensity, GCT, was determined by analysing the relative Raman intensity as a function of the potential, taking into account voltage‐dependent coverage of the silver electrode. The total chemical effect was defined as a product of GCT and the so‐called ‘active‐sites’ effect and was estimated as equal to about 50.
Raman and far‐infrared spectra of formamide at temperatures down to 20 K
Authors: Torrie B. H. , Brown B. A. 
Published: May 2005

AbstractThe Raman and infrared wavenumbers of solid HCONH2 and DCOND2 were measured at 20 K and high temperatures. More peaks were observed in both the lattice and internal mode regions than were expected from the known structure, so the structure was redetermined. The resulting structure is in agreement with earlier determinations, so the extra peaks are attributed to second‐order effects produced by a large anharmonicity associated with the hydrogen bonds. Attempts to model the structural details and the lattice dynamics had only a limited success, which may again be attributed to anharmonic effects and to the basic inadequacies of the models.
Surface‐enhanced Raman spectra using silver‐coated paper substrates
Authors: Lee Arthur S. L. , Li Ying‐Sing 
Published: May 2005

AbstractBecause of the importance of developing an active substrate for surface‐enhanced Raman (SER) spectroscopic applications, a silver‐coated filter‐paper substrate was prepared for surface‐enhanced Raman scattering (SRS) by using a chemical reduction method at room temperature. Optimization of the silver deposition time was achieved by using p‐nitrophenol (PNP) as an analyte. Its performance as an SERS‐active substrate was tested using PNP, p‐chlorobenzoic acid, m‐chlorobenzoic acid and o‐chlorobenzoic acid. To overcome the problem of low enhancement when a dipping method was adopted for sample applications, a silver‐coated alumina‐based substrate was prepared. The new substrate was found to exhibit strong SERS with both the solution and the dipping methods for sample applications of PNP. Using the new substrate, the limit of detection for methyl red was estimated to be 3 ng ml−1.
Micro‐Raman study of BaTiO3 thin films prepared by the metallo‐organic decomposition technique
Authors: Ching‐Prado E. , Katiyar R. S. , Santiago‐Aviles J. J. 
Published: May 2005

AbstractA micro‐Raman probe was used to characterize thin films of barium titanate synthesized by metallo‐organic decomposition and rapid thermal annealing techniques. All films were found to be polycrystalline aggregates with perovskite as the primary phase. The optimum film processing procedure as evidenced by the micro‐Raman probe was a combination of rapid thermal annealing at 950°C in an oxygen or argon atmosphere. Fourier transform infrared spectra indicated that samples annealed in a vacuum show higher carbon contamination than those receiving the same heat treatment in an oxygen or argon atmosphere.
Construction of third and fourth rank tensors for the triclinic, monoclinic and orthorhombic crystal classes
Authors: Leuchs M. , Kiefer W. 
Published: May 2005

AbstractA simple method is described for constructing symmetry‐allowed polar tensors for n‐photon processes of rank three and four by using polar tensors of rank one and two. The consideration is restricted here to the triclinic, monoclinic and orthorhombic crystal classes and intrinsic symmetry is not taken into account. Expansion to higher order tensors is possible.
Solid‐phase transitions in TlHSO4 crystal
Authors: Le Calve N. , Pasquier B. , Romain F. , Taffin A. 
Published: May 2005

AbstractPolycrystalline TlHSO4 was investigated by calorimetry (253–423 K) and by infrared (10–300 K) and Raman (10–420 K) spectroscopy. Two phase transitions are detected at 320 and 388 K. A complete assignment of the spectra of the room‐temperature phase (III) is given and the spectroscopic results are consistent with infinite chains of hydrogen bonds. This structure appears disordered above 320 K (phase II). The high‐temperature phase (I) presents the characteristic features of a plastic phase according to the spectroscopic manifestations of an increasing orientational disorder of sulphate ions. Above 360 K, a metastable phase (I′) showing a complex hydrogen‐bonded framework is identified.
Instrument for natural and magnetic Raman optical activity studies in right‐angle scattering
Authors: Hecht Lutz , Barron Laurence D. 
Published: May 2005

AbstractA simple computer‐controlled instrument for natural and magnetic incident circular polarization Raman optical activity (ICP ROA) measurements in right‐angle scattering is described. The key spectral elements consist of a fast single‐stage monochromator equipped with a holographic notch filter, a highly efficient holographic diffraction grating and a thinned back‐illuminated, thermoelectrically cooled charge‐coupled device (CCD) detector. A temperature‐stabilized longitudinal electro‐optic modulator is employed to switch between orthogonal circular polarization states in the incident laser radiation. A polaroid film together with a mica half‐wave retardation plate are used to select particular linear polarization states in the Raman scattered radiation with the same instrumental response. High‐quality depolarized and polarized Stokes and depolarized anti‐Stokes ICP ROA spectra of (R)‐(−) and (S)‐(+)‐phenyloxirane and depolarized magnetic resonance ICP ROA spectra of copper(II) tetrabromide are presented as typical examples of the excellent performane characteristics.
Resonance CARS studies on acridine in the electronic excited T1 state
Authors: Bischof T. , Kiefer W. 
Published: May 2005

AbstractCARS measurements were carried out on acridine to investigate the resonance behaviour of the totally symmetric vibration in the lowest excited triplet electronic state. The lineshapes of the observed vibrational mode were analysed for different pump laser wavenumbers by means of the transform theory in the Condon approximation. Under this condition the experimentally determined CARS excitation profile was compared with that calculated from the measured Tn ←T1, absorption spectrum.
Vibrational spectra and conformations of isopropyl thiocyanate and its d6 and d7 deuterated analogues
Authors: Jozwiak R. N. , Karlsson A. , Klaeboe P. , Nielsen C. J. 
Published: May 2005

AbstractThe Raman and IR spectra of isopropyl thiocyanate, isopropyl‐1,1,1,3,3,3,‐d6 thiocyanate and isopropyl‐d7 thiocyanate were recorded as vapours, liquids and amorphous and crystalline solids. IR matrix isolation spectra were recorded in argon and in nitrogen matrices at 14 K, using the hot nozzle technique. Two conformers with Cs, symmetry (anti) and C1, (gauche) were present in the vapour and liquid states whereas only one conformer (anti) existed in the crystal. The enthalpy difference was measured to be ΔH° (gauche‐anti) = 2.4 ± 0.2 kJ mol−1 in the liquid from variable‐temperature Raman spectra. In argon matrices a value of 2.3 ± 0.3 kJ mol−1 was obtained in the temperature range 300–600 K, similar to the value in nitrogen matrices, both assumed to be valid for the vapour phase. Annealing experiments indicated the barrier of gauche–anti conversion to be around 9 kJ mol−1. Quantum chemical calculations with the basis sets STO–3G, 3–21G* and 6–31G* were carried out The energy difference between the conformers was calculated and scaled ab initio force constants were employed in normal coordinate calculations. Complete assignments of Raman and IR bands belonging to the anti conformer of the parent molecule and the isotopomers were carried out. Only a limited number of bands characteristic of the gauch conformer were observed since most of its Raman and IR bands overlapped those of the anti conformer.
Assignment of adenine ring in‐plane vibrations in adenosine on the basis of 15N and 13C isotopic frequency shifts and TUV resonance Raman enhancement
Authors: Toyama Akira , Hanada Naoki , Abe Yoshiharu , Takeuchi Hideo , Harada Issei 
Published: May 2005

AbstractInfrared, Raman and UV resonance Raman spectra of adenosine and its 1,3‐15N2, 2–13C, and 8–13C isotopic analogues were measured in neutral aqueous solution (Raman and UV Raman) and in the crystalline state (infrared and Raman). The observed isotopic wavenumber shifts are useful in distinguishing adenine ring vibrations from ribose vibrations. In‐plane modes of the adenine ring are selectively enhanced in UV resonance Raman spectra, which facilitates the assignment of the in‐plane vibrations. In addition to the in‐plane modes, a ribose vibration coupled with adenine in‐plane vibrations was identified in the UV resonance Raman spectra. The fundamental wavenumbers for 22 in‐plane normal modes of the 9‐substituted adenine ring of adenosine in the 1700–250 cm−1 region are proposed. Although the fundamental wavenumbers of adenosine correspond well with those of adenine above 1350 cm−l and below 800 cm−1 the vibrations in the 1350–800 cm−1, region are appreciably affected by the presence of the N‐9—C‐1′ glycosidic bond and the couplings between ribose and adenine ring vibrational motions. The adenosine fundamental wavenumbers and their isotopic shifts reported here may be useful in analysing vibrational spectra of adenine nucleosides and nucleotides and in improving the force field of the 9‐substituted adenine ring.
Application of near‐infrared‐Fourier transform Raman spectroscopy in medical research
Authors: Keller Stefan , Schrader Bernhard , Hoffmann Andreas , Schrader Wolfgang , Metz Klaus , Rehlaender Achim , Pahnke Jörg , Ruwe Markus , Budach Wilfried 
Published: May 2005

AbstractUsing NIR–FT Raman spectroscopy we have obtained useful spectra of many kinds of biomaterials. These spectra contain—with only simple sample preparation—information that can be used both for component analysis and for tissue identification. In addition, pathological changes in the spectra of eye lenses and of brain, liver and colon tissues are observed, demonstrating the usefulness of the technique as a tool of medical diagnosis.
Vibrational conformational analysis of ethyl formate
Authors: Maes I. I. , Herrebout W. A. , van der Veken B. J. 
Published: May 2005

AbstractInfrared (4000–50 cm−1) spectra of gaseous, amorphous and crystalline ethyl formate, HCOOCH2CH3, were recorded. Raman spectra of the gaseous, liquid and solid phases were investigated from 3500 to 25 cm−1. Additionally, qualitative depolarization ratios were obtained from the Raman spectra of the liquids. Ab initio calculations were carried out using a 4–21G basis set and show that the compound can occur as four possible conformers, s‐cis trans, s‐cis, gauche, s‐trans trans and s‐trans, gauche. Their optimized structural parameters, their force field and the vibrational wavenumbers and potential energy distributions were calculated for each conformer. Additionally, the potential function governing internal rotation from the s‐trans, trans to the s‐cis trans conformation was calculated. Both the s‐cis conformers were identified in the vibrational spectra of the gaseous, amorphous and fluid phases, and there are strong indications that a weak band at 623.5 cm−1 in the Raman spectrum of the fluid phases is due to one of the s‐trans conformers. From a temperature study of the Raman spectrum of the liquid, the enthalpy difference between the cis, trans and s‐cis gauche conformers was determined to be 1.4 ± 0.4 kJ mol−1 with the trans conformer being the more stable rotamer. Vibrational spectra of the crystalline solid, which consists only of the s‐cis, trans conformer, showed that ethyl formate can crystallize in two different forms. A complete assignment of the vibrational fundamentals from the infrared and Raman spectra is proposed.
Confocal three‐dimensional scanning laser Raman–SERS–fluorescence microprobe. Spectral imaging and high‐resolution applications
Authors: Sharonov Sergey , Nabiev Igor , Chourpa Igor , Feofanov Alexey , Valisa Paolo , Manfait Michel 
Published: May 2005

AbstractA multi‐purpose instrument which allows the recording of confocal micro‐Raman, micro‐SERS and micro‐fluorescence spectral images of sample areas from 5 × 5 to l50 × l50 μm with a lateral resolution of ca. 0 3 μm and an axial resolution of ca. 1 μm was developed. The instrument is a combination of two spectrometers both coupled to the same microscope, motorized sample stage, confocal entrance chamber, macro‐sample chamber and CCD detector. The first spectrometer includes a double monochromator coupled with a spectrograph and exhibits the properties of a typical high‐resolution Raman instrument permitting measurements of the low‐wavenumber regions of the spectra. The second spectrometer includes a Notch filter and a spectrograph equipped with two interchangeable low‐dispersion gratings and exhibits the properties of a high‐luminosity spectrometer, suitable for low resolution, over a wide spectral range and highly sensitive micro‐Raman and microfluorescence measurements. The choice of spectrometer most suitable for a particular application can be made automatically without additional prealignment of the system. The system of optical scanners operating in the confocal mode and two‐dimensional CCD detection allow the accumulation of spectra from hundreds of points of the sample under the microscope simultaneously. A computer‐controlled scanning sample stage and a system using a ‘scanning line’ of the laser beam allow fast recording of well resolved confocal spectral images (CSI) without sample degradation. Conventional images of species could be recorded with a TV–CCD camera through the microscope optics. The software supports all stages of CSI recording and allows the combined treatment of conventional and spectral images including their spatial calibration and conversion of spectral image into a conventional image, to assign point‐by‐point the spectral data to the conventional image. The applicability of the instrumentation and techniques to the study of polymeric materials, industrial samples and fluid inclusions in minerals was demonstrated. Spectral images based on the micro‐SERS analysis of an antitumour drug adsorbed on the hydrosol were recorded and are discussed in terms of their application to the micro‐SERS imaging studies of living cells.
Crossing of anisotropic and isotropic Raman components in the intermolecular resonance coupling of vibrations. II—LiClO4 and LiI solutions in acetone
Authors: Kecki Zbigniew , Sokolowska Anna 
Published: May 2005

AbstractChanges in the wavenumbers of the anisotropic and isotropic components of the CO stretching band in the Raman spectrum of LiClO4 and Lil solutions in acetone were investigated. The non‐coincidence values defined as Δν = νaniso – viso of the CO band in LiCIO4 solutions were positive for bulk acetone and negative for the acetone‐shared ion pairs. In LiI solutions, where the separation of bulk acetone was not possible, the non‐coincidence values changed from positive to negative with increasing concentration of LiI. A mechanism for the non‐coincidence changes is proposed.
Raman and infrared spectra, conformational stability, barriers to internal rotation, vibrational assignment and ab initio calculations of 3‐bromo‐2‐methylpropene
Authors: Durig J. R. , Eltayeb Saadia , Guirgis Gamil A. 
Published: May 2005

AbstractThe Raman (3200–20 cm−1) and infrared (3200–35 cm−1) spectra of 3‐bromo‐2‐methylpropene, H2CC(CH3)CH2Br were recorded for the gas and solid. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. The fundamental asymmetric torsional mode for the gauche conformer is observed at 81.5 cm−1 with one excited state falling at a lower wavenumber but the asymmetric torsion is not observed for the higher energy s‐cis conformer. Utilizing the gauche observed torsional wave numbers, the gauche dihedral angle, the enthalpy difference between conformers and the calculated torsional fundamental wavenumber for the s‐cis conformer, the potential function governing the interconversion of the rotamers was estimated. This potential function gives values of 170 cm−1 (486 cal mol−1) (1 cal = 4.184 J), 2659 cm−1 (7.60 kcal mol−1) and 725 cm−1 (2.07 kcal mol−1) for the s‐cis to gauche, gauche to gauche and gauche to s‐cis barriers, respectively, and it is compared with tht obtained with the RHF/STO‐3G* basis set. From the methyl torsional wavenumber of 172 cm−1 for the gauche conformer, the threefold barrier of 695 cm−1 (1.99 kcal mol−1) was calculated for the methyl group. A complete vibrational assignment is proposed based on Raman : depolarization data, group wavenumbers and relative infrared and Raman intensities. The conformational energy difference and optimized geometries of both conformers were also obtained from ab initio calculations with the RHF/STO‐3G*, RHF/LANL1DZ and MP2/LANL1DZ basis sets. Normal‐coordinate analyses were also performed with force fields determined from both the RHF/STO‐3G* and RHF/LANL1DZ basis sets. The calculated wavenumbers support the proposed vibrational assignment. These data are compared with the corresponding data for some similar molecules.
Quantitative study of self‐absorption in near‐infrared Fourier transform Raman spectroscopy
Authors: Everall N. 
Published: May 2005

AbstractSelf‐absorption occurs in near‐infrared Fourier transform (NIR‐FT) Raman spectroscopy when the absolute frequency of a Raman band coincides with an NIR absorption band of the scattering material. This is manifested by selective attention of specific Raman bands, the degree of which depends on the sample pathlength, concentration and position in the laser beam. These factors can introduce serious errors in quantitative FT Raman applications unless care is taken. This paper describes a simple analysis which allows quantitative predictions of the effects of varying sample concentration and collection optics geometry. The predictions for concentration variation have been validated by experiment. A consideration of the experimental design required to minimize self‐absorption indicates that this will also reduce instrument sensitivity and ease of alignment; therefore, there is a trade‐off between optimizing instruments for quantitative applications whilst maintaining sensitivity and ease of use.
Low wavenumber Raman scattering in viscous liquids
Authors: Zwick A. , Landa G. 
Published: May 2005

AbstractLow‐wavenumber depolarized Raman spectra (−400 to 400 cm−1) for dioxane, water and glycerol are presented. Stokes and anti‐Stokes spectra (−400 to 400 cm−1), are used to define a reduced spectrum, in which the effects of temperature and also flat backgrounds and symmetric central components are removed, without knowledge of these parameters. Comparison with the usual reductions shows that (i) all inelastically scattered photons must be considered as ‘true’ Raman signals, due to processes involving Boson‐like excitations, (ii) if central scattering exists, then its intensity also depends on the population factor, (iii) the low‐wavenumber Stokes signal is more intense than expected for a factor of n + 1 only, owing to non‐linear effects, and (iv) the systematic use of reduced spectra is not essential, and can be hazardous in some cases.
Lattice dynamic analysis of Raman data from tin tetrabromide: Chains at high pressures
Authors: Ghrist R. W. , Lee S. A. 
Published: May 2005

AbstractA lattice dynamic model of chains of SnBr4 molecules is developed to analyze previously published Raman data at high pressures. This model is used to evaluate both the intra‐ and intermolecular bonding in SnBr4 up to about 10 GPa. The effective force constant associated with the intramolecular SnBr bond is found to increase in an approximately linear manner with pressure. The effective force constant of the intramolecular BrBr bond shows a dramatic decrease of about 30% near 6 GPA, the pressure at which chains of molecules begin to form in SnBr4. The effective force constant associated with the intermolecular BrBr bond rises linearly with pressure after the chains begin to form.
Resonance Raman and time‐resolved resonance Raman studies of ruthenium(II) complexes of 2,2′‐bipyridine and 5‐monomethyl‐2,2′‐bipyridine. Evidence for polarization of the 3MLCT state electron density in the asymmetric ligand
Authors: Treflert‐Ziemelis Shelly M. , Kincaid James R. 
Published: May 2005

AbstractThe resonance Raman and time‐resolved resonance Raman (TR3) spectra of ruthenium(II) complexes containing the asymmetric (RR)(5‐methyl‐2,2′‐bipyridine) ligand, Ru(5‐mmb), and its methyl‐deuterated analogue, Ru(5‐d3‐mmb), are reported. The spectra are compared to those of tris(2, 2′‐bipyridine)ruthenium(II), Ru(bpy), and tris(5,5′‐dimethyl‐2,2′‐bipyridine)ruthenium(II), Ru(5,5′‐dmb), and its deuterated analogue, Ru(5,5′‐d6‐dmb). The ground‐state spectrum for the asymmetric chelate is interpretable in terms of vibrationally isolated fragments with the exception of the modes involving the inter‐ring and adjacent bonds. In addition, the TR1 spectra are shown to be consistent with slight polarization of the (triplet) metal‐to‐ligand charge‐transfer, 3MLCT, excited‐state charge distribution toward the pyridinc fragment of the chelated anion.
Synthesis and polarized Raman studies of rhombohedral LuOCl single crystals
Authors: Burns J. B. , Stump N. A. , Peterson J. R. 
Published: May 2005

AbstractThe polarized Raman spectra of SmSI‐type rhombohedral LuOCl were recorded at various polarization orientations. The polarized spectra were analyzed to determine the symmetry assignments of the Raman‐active transitions. The Raman spectra of polycrystalline and single‐crystal LuOCl are characterized by five features. Analysis of the intensity enhancements of the three lattice vibrations at 139, 272 and 496 cm−1 indicate an Eg symmetry, whereas those at 86, 139 and 473 cm−1 exhibit intensity enhancements which indicate an A1g symmetry.