bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman spectra of thin solid films. VII–Uranyl superphtalocyanine
Authors: Clavijo R. E. , Aroca R. , Kovacs G. J. , Jennings C. A. , Duff J. , Loutfy R. O.
Published: May 2005

Raman and infrared spectra of evaporated uranyl superphthalocyanine (UO2SPc) films are reported. Raman spectra of UO2SPc (formed by five isoindoline subunits) depart from the general spectral trends observed in metallated phthalocyanines (four isoindoline subunits), and are indicative of very low molecular symmetry. Surface enhanced Raman scattering (SERS) spectra obtained on silver island films show appreciable differences from the normal unenhanced Raman spectra. This is unlike the situation for normal metallated phthalocyanines (where the SERS is simply the enhanced version of the normal Raman spectrum) and indicates a different interaction mechanism between the UO2SPc molecule and the metal islands.
Vibrational characterization of aluminum–oxo phthalocyanine films. IR, Raman and surface‐enhanced Raman spectroscopic studies
Authors: Zeng Z. Q. , Aroca R. , Hor A. M. , Loutfy R. O.
Published: May 2005

The vibrational characterization of bis(phthalocyanatoaluminum) oxide [(PcAl)2O] was attempted using infrared, Raman, SERS, RRS and SERRS spectra of thin solid films. Vibrational fundamentals observed for microcrystallites of (PcAl)2O dispersed in KBr, evaporated thin films and at submonolayer coverage of a SERS active surface were identified with characteristic vibrational frequencies of the phthalocyanine (Pc) moiety. Evidence for a certain degree of molecular organization in the evaporated thin solid films is presented, based on IR and Raman data.
Raman difference spectroscopy in measurements of molecules and molecular groups inside proteins
Authors: Yue Kwok To , Deng Hua , Callender Robert
Published: May 2005

In order to obtain the Raman spectra of small molecules inside proteins (or other large macromolecules) and/or small molecular groups of a protein, techniques were developed to perform sensitive Raman difference spectroscopy. The macromolecule–small molecule complex Raman spectrum is taken in addition to the Raman spectrum of the macromolecule, and the two are computer subtracted. For studies on proteins, it is necessary to use optical multichannel detectors, as spectrometers employing photomultiplier detectors are too slow optically to collect signals from dilute samples. The apparatus is described and characterized in detail. A subtraction fidelity of 0.1% can be achieved for samples, such as proteins, which contain broad bands in their Raman spectra. Hence it is possible to obtain fairly good Raman spectra of very small molecular groups inside proteins. An example from recent work is presented.
Resonance Raman investigation of the interaction of benzoquinone with amino acids
Authors: Santos P. S. , Gonçalves N. S.
Published: May 2005

The interaction of p‐benzoquinone with proline, pyrrolidine, trytophan and glutathione was investigated by resenance Raman spectroscopy. The intensely coloured solutions formed show an absorption maximum around 530 nm and the excitation of the Raman spectra in resonance conditions indicated in all cases an enhancement of several benzoquinone modes. Such behaviour strongly suggests the formation of an n–π* charge‐transfer complex, as suggested previously by other workers. The ESR spectra of the coloured solutions preclude the benzoquinone anion radical as the main chromophoric species in solution.
Raman spectrum of the [SnI3]− ion and other halogenostannate(II) complexes including mixed halides
Authors: Taylor Michael J.
Published: May 2005

The complete Raman spectrum of the pyramidal triiodostannate(II) ion [SnI3]− (ν1 = 162 cm−, strong, polarized; ν2 = 61 cm−, medium, polarized; ν3 = 148 cm−, strong, depolarized; ν4 = 48 cm−, strong, depolarized) is observed in a diethyl ether extract from a solution of tin(II) iodide containing hydriodic acid. Previous reports of the frequencies of [SnCl3]− are confirmed but for [SnBr3]− ν1 is revised from 211 to 205 cm−1. The complex acids H[SnX2Y] and H[SnXYZ] (X, Y or Z = Cl, Br or I) are observed in solvent extracts of tin(II) mixed halide solutions and a set of ν(Sn—halogen) frequencies is compiled. Appreciable co‐extraction of [SnX2(H2O)] occurs at halogen acid concentrations below 3 mol l−1.
Vibrational spectra and normal coordinate analysis of crystalline 3‐(4‐chlorophenyl)‐2‐cyanopropenonitrile
Authors: Bugueno‐Hoffmann R. , Meinnel J.
Published: May 2005

The polarized Raman and infrared spectra of crystalline 3‐(4‐chlorophenyl)‐2‐cyanopropenonitrile between 3150 and 3190 cm−1 are reported. The assignments of the different modes are discussed. To check the vibrational assignment, normal coordinate analysis was carried out. The force field consists of 110 force constants, 63 of which were transferred from benzene, chlorobenzene and tetracyanoethylene. Good agreement between most observed and calculated values was found, although there were some discrepancies between calculated and observed frequencies.
Surface‐enhanced Raman scattering of the redox pair CO(sep)3+/Co(sep)2+ on silver and copper electrodes
Authors: Bertolino J. R. , Temperini M. L. A. , Sala O.
Published: May 2005

The surface‐enhanced Raman spectra of the redox pair Co(sep)3+/Co(sep)2+ (sep: sepulchrate) adsorbed on silver and copper electrodes have been obtained in the skeletal region for these compounds and the results were consistent with the redox potential of the species. The role of the anions and cations of the support electrolytes in the adsorption of the Co(sep)3+ on a silver electrode suggests that the compound is adsorbed on the electrode via ion pair formation with the anion specifically adsorbed. From the behaviour of the Raman intensity of the CH2 symmetrical stretching vibration it was possible to estimate the pKa of the Co(sep)2+.
SERS of langmuir–blodgett monolayers: N‐octyl‐3,4:9, 10‐perylenetetracarboxylic monoanhydride and monoimide
Authors: Guhathakurta‐Ghosh U. , Aroca R. , Loutfy R. O. , Nagao Y.
Published: May 2005

The vibrational spectra of n‐octyl‐3,4:9, 10‐perylenetetracarboxylic monoanhydride (Oc‐PTCDO) and of n‐octyl‐3,4:9,10‐perylenetetracarboxylic monoimide (Oc‐PTCDNH) have been studied. Langmuir‐Blodgett (LB) films of both dye pigments were prepared and transferred to glass slides and silver surfaces for spectroscopic characterization. Using mixed LB monolayers of Oc‐PTCDNH and arachidic acid, the surface‐enhanced fluorescence of the monomer and aggregates was distinguished.
Stokes and anti‐stokes Raman scattering and electronic emission studies on dysprosium‐doped YBa2Cu3O7–δ
Authors: Bist H. D. , Gurjar R. , Upadhyay P. , Khulbe P. K. , Rao C. V. N. , Agarwal S. K. , Narlikar A. V. , Little T. S. , Durig J. R.
Published: May 2005

Laser‐excited emission from YBa2Cu3O7–δ with 7.5% dysprosium nominally subsituted in place of yttrium is presented in the range 13 000–23 000 cm−1. In addition to the reported Raman lines in the CuO stretching region, a number of other spectral features were observed. These include a discrete luminescence with lines at 14 400 and 14 425 cm−1 and a broad emission with its peak position and band width varying with excitation wavelength. Additionally, an anti‐Stokes scattering, which has no apparent counterpart in the Stokes region, was observed. These observations may be of significance in the elucidation of the mechanism of high‐temperature superconductivity.
Surface‐enhanced Raman spectroscopy of biomolecules. Part I.—water‐soluble proteins, dipeptides and amino acids
Authors: Chumanov G. D. , Efremov R. G. , Nabiev I. R.
Published: May 2005

Surface‐enhanced Raman (SER) spectra of water‐soluble proteins (lysozyme and bovine serum albumin), dipeptides and amino acids were analysed. Chemisorption is a necessary condition for the appearance of SER spectra on silver electrodes and hydrosols for these compounds. The Raman cross‐section enhancement per molecule may reach a factor of 105–106, depending closely on the frequency of the vibration band considered. The mechanism of enhancement has a short‐range character and is attributed to the π‐electron complexes of the aromatic amino acids side‐chains and σ‐complexes of the molecular groups containing unshared electron pairs with the metal. The effect of induced optical activity in the visible region for aromatic amino adsorbed by silver hydrosols has been elucidated.
Fourier transform Raman spectroscopy in the near‐infrared region
Authors: Crookell A. , Hendra P. J. , Mould H. M. , Turner A. J.
Published: May 2005

A comparison of the relative optical throughput (étendue) merits of near‐infrared Fourier transform (FT) and conventional dispersive Raman spectrometers is presented. Design details of an FT Raman system are described and some examples are given to illustrate the performance of the system.
Raman spectroscopic structural studies on the stepwise dehydration of Zn(BrO3)2 · 6H2O
Authors: Srinivasan T. K. K. , Devanathan T.
Published: May 2005

Raman spectra of single‐crystal Zn(BrO3)2 · 6H2O were examined at 298, 338 and 378 K from the fully hydrated to the totally anhydrous state. At 298 K, the presence of only one set of OH stretching bands in the Raman spectrum confirmed the structural equivalence of the six water molecules. At 338 K, the spectrum of the dihydrate indicated splittings in the OH stretching region attributable to the non‐equivalent H2O groups. Thechanges in the internal modes of the BrO3− revealed lifting of degeneracy as a consequence of lowering of site symmetry. Conclusions drawn from Raman spectral investigations conformed to the change in site symmetry of BrO3− from C3 to C1.

Differential scanning calorimetric data indicated the formation of dihydrate and anhydrous compound of Zn(BrO3)2 involving a two‐step dehydration process. X‐ray powder diffraction patterns recorded at different temperatures were analysed and indexed on unit cells of cubic symmetry. The results from Raman studies with reference to change in the site symmetry of BrO3− in conjunction with x‐ray powder pattern analysis led to the deduction of the space group for the anhydrous compound. Vibrational selection rules for the anhydrous compound were determined on a proposed space group P23(T1).
Observation of morphology‐dependent resonances caused by the input field in the Raman spectrum of microdroplets
Authors: Schweiger G.
Published: May 2005

Strong peaks in the Raman spectrum of optically levitated microdroplets were observed and are caused by input resonances. These peaks are generated as the amplitude of the transmitted field is enhanced resonantly if the size of the slowly evaporating droplets fulfils the resonance condition. The spectral position of these peaks is independent of the Raman spectrum. The input resonance peaks appear in the Raman spectrum in addition to the output peaks and can be distinguished from the latter by their spectral shape.
Methyl internal rotation in the α‐, β‐ and γ‐picolines‐CHD2 in the gas phase
Authors: Cavagnat D. , Lautie M. F.
Published: May 2005

Gas‐phase infrared and Raman spectra of the three isomeric selectively deuteratedγ‐, β‐ and α‐picolines (C5ND4CHD2) were recorded in the CH stretching region. They are each characterized by a strong band and a weaker band at a lower frequency, the intensity of which increases progressively from the Para (γ‐) to the ortho (α‐) isomer. These bands exhibit simple Raman profiles but their infrared contours are of A and C type, respectively. A quantum treatment of these spectra, assuming an anharmonic coupling of the ν(CH) mode with the internal rotation of the CHD2 group, is developed in the adiabatic approximation. This model leads to a good fit of the experimental Raman band shapes and a good picture of the observed infrared spectra. The frequency of the intense band is assigned to the frequency of the ν(CH) mode during the almost free rotation of the CHD2 group; the weaker band corresponds to the frequency of the CH bond in the plane perpendicular to the pyridine ring (γ‐picoline) or in a plane tilted by about ± 120° from the pyridine ring (β‐ and α‐picoline). The frequency difference between ν∥(CH in the molecular plane) and ν⟂ (CH in the plane perpendicular to the molecular plane) is found to increase from γ‐ to α‐picoline, as does the internal rotation barrier height; the most stable conformations of the methyl group with respect to the pyidine ring are thus determined. These results provide new evidence for the importance of hyperconjugation effects in such methylated aromatic molecules.
Raman spectroscopic study of the effects of opiates on dipalmitoylphosphatidylcholine dispersions
Authors: Yova D. , Zouboulis I. , Liarokapis E. , Loukas S.
Published: May 2005

The effects of the opiates levorphanol and naloxone on the thermotropic properties of dipalmitoylphospalidylcholine (DPPC) multilamellar dispersions were studied using Raman spectroscopy. The spectra of DPPC dispersions were recorded in the CH stretching mode region. By examining the intensity ratios I2880/I2850 and I2930/I2880 as a function of temperature, it was found that opiates lowered the pretransition temperature of DPPC by 2°C and decreased the lateral packing of the acyl chains of the phospholipids.
Multiple vibrational resonances in the Raman spectra of liquid ethanes
Authors: Korppi‐Tommola Jouko , Sundius Tom , Shurvell H. F. , Daunt S. J.
Published: May 2005

The Raman spectra of liquid ethane, ethane‐d3 and ethane‐d6 were recorded and analysed. The CH3 and CD3 stretching regions were computer resolved using Cauchy‐Gaussian and Voigt functions to account for asymmetric band shapes. Multiple vibrational resonances were investigated using the wavenumbers and observed intensities in these regions. The developed basis functions show strong mixing of the levels in these regions. In general the resonances appear to be less strong in the liquid phase than reported in previous studies of the gaseous state. Some new assignments in the liquid‐state spectra of ethanes could be suggested.
High‐pressure micro‐Raman spectra of potassium hexabromostannate(IV), K2SnBr6
Authors: Butler Ian S. , Huang Yining
Published: May 2005

High‐pressure micro‐Raman spectra of crystalline K2SnBr6 were measured at ambient temperature up to 50 kbar using a diamond‐anvil cell. A pressure‐induced phase transition occurs at ca. 19 kbar. All the observed bands show blue shifts with pressure. The Grünesisen parameters (calculated from the pressure coefficients) for the high‐pressure phase are smaller than those for the ambient temperature/pressure monoclinic phase, indicating that the high‐pressure phase is denser and less compressible than the monoclinic phase.
Infrared and polarized Raman spectra of TlLa(SO4)2 · 2H2O
Authors: Mathew Xavier , Suresh G. , Pradeep T. , Nayar V. U.
Published: May 2005

IR and polarized Raman spectra of a TlLa(SO4)2 · 2H2O crystal were recorded and analysed. The bands observed in the internal mode region of the SO ion indicate the presence of two crystallographically distinct SO ions in the crystal, in agreement with the x‐ray diffraction data. These SO ions have stronger SO bonds than a free SO4 ion. The water molecule forms hydrogen bonds of medium strength.
Theory of distortion‐induced non‐zero value of the depolarization ratio of the totally symmetric ν1 mode of CCl4 in the liquid state
Authors: Bhattacharjee R.
Published: May 2005

A theory of the distortion‐induced non‐zero value of the depolarization ratio [ρ⟂(π/2)] of the totally symmetric vibrational mode of a tetrahedral (Td) molecule in the liquid state is formulated. As an example, the depolarization ratio of the ν1 mode of the CCl4 (Td) molecule in the liquid state is discussed. It is concluded that the non‐zero value of the depolarization ratio of the totally symmetric ν1 mode of CCl4 arises from the distortion of the C1 symmetry of the structure of the molecular unit in the liquid state.
Acyl chain packing properties of deuterated lipid bilayer dispersions: Vibrational Raman spectral parameters
Authors: Devlin Mark T. , Levin Ira W.
Published: May 2005

The phase, packing and dynamic behavior of model membrane systems consisting of lipids with completely deuterated chains is generally monitored by the temperature dependence of the line width of the methylene (CD2) symmetric stretching modes located at ∼2100 cm−1 1–5 Alternative empirical spectral parameters derived from the peak‐height intensity ratios of spectral features assigned to the chain CD methylene and methyl stretching modes are introduced and evaluated. In particular, specific intensity ratios reflect a sensitivity to average inter‐ and intra‐chain order–disorder properties of the portions of the lipid chains localized either near the methyl termini or near the head‐group–acyl chain interface. The utility of these intensity parameters is evaluated by examining the bilayer behavior of binary mixtures of dipalmitoylphosphatidylcholine with fully deuterated lipid chains (DPPC‐d62) and dipalmitoylphosphatidylcholine with non‐deuterated chains (DPPC‐do) in various physical states. We also assess the use of intensity parameters for clarifying the effects of ethanol on the inter‐ and intra‐chain interactions of DPPC‐d62 bilayers. In the DPPC‐d62–ethanol system particular emphasis is placed on the formation of the novel interdigitated chain gel phase.
Vibrational study of the paraelectric superionic phase transition in ammonium hydrogenselenates, NH4HSeO4 and ND4DSeO4
Authors: Pasquier B. , Le Calvé N. , Rozycki A. , Novak A.
Published: May 2005

Raman and infrared spectra of the room‐temperature ‘paraelectric’ (II) and high‐temperature (I) superionic phases of NH4HSeO4 and ND4DSeO4 were investigated at different temperatures in the range 300–450 K. A new intermediate phase I′ is identified on cooling phase I. A complete assignment of the bands of phase II is given and the spectroscopic manifestations of the structural disorder due to both the statistical distribution of OH …︁ O protons and orientational disorder of ammonium ions were studied. In the superionic phase I infinite (HSeO4−)n chains are broken and open dimers appear to be formed. There is increasing orientational disorder of both ammonium and HSeO4− ions resulting in a plastic state. Hydrogen bonding in various phases is discussed.
IR and single‐crystal Raman spectra of Te(OH)6 · 2CO(NH2)2
Authors: Philip Daizy , Abraham Sunila , Aruldhas G.
Published: May 2005

IR and single‐crystal Raman spectra of Te(OH)6 · 2CO(NH2)2 were recorded and analysed. Vibrational bands due to OH bonds and TeO6 and (NH2)2CO groups are identified. From the spectra it is concluded that the TeO6 groups occupy C2 sites and the urea molecules vibrate independently in the crystal.
Comparison of transform and sum‐over‐states methods in the resonance Raman excitation profile of cryptoxanthin
Authors: Hoskins L. C. , Pham A. X. , Rutt G. C.
Published: May 2005

The resonance Raman excitation profiles (RREPs) of the ν1, ν2 and ν3 vibrations of cryptoxanthin in acetone, toluene and carbon disulfide solvents have been determined. Cryptoxanthin, which is a pigment in maize, differs from β‐carotene by having a hydroxyl group on one of the end rings. The RREPs are interpreted in terms multimode sum‐over‐states and trates and transform methods. Both theoretical procedures show good agreement between theory and experiment, but the results in carbon disulfide show the greatest discrepancy. The theoretical parameters for cryptoxanthin are similar to those of β‐carotene, but the broadening effect in cryptoxanthin is about 20% smaller than in β‐carotene. The sum‐over‐states method gives better agreement between theory and experiment in acetone and toluene solvents, whereas the transform method is better in carbon disulfide.
Raman difference spectroscopy under computer control
Authors: Strube M. M. , Meinander N. , Laane J.
Published: May 2005

The design and operation of a Raman difference spectrometer (RDS) are described. The system is operated under computer control and permits the spectra of up to four different samples to be recorded at the same monochromator settings. Since this eliminates any relative errors in the frequencies, very accurate frequency difference measurements can be made. The system aslo permits easy calculation of the isotropic and anisotropic components of the Raman spectra when polarization techniques are used. Essential features of the RDS system include the Raman spectrometer, the computer, an interface and various types of sampling devices (a rotating cell assembly, a rotating lens and a moving lens apparatus). The position of the sampling assemblies is monitored using photodiodes. The programs for data collection and manipulation are described. Several different spectra, representative of different kinds of applications, are presented.
Vibrational spectra and structure of tricyclopropylsilane
Authors: Wurrey Charles J. , Holder Andrew J. , Green Peter M.
Published: May 2005

The Raman spectra of tricyclopropylsilane were recorded for the condensed phases of this molecule, and infrared spectra (4000–400 cm−1) were obtained for all three states of this compound. In addition, a survey microwave spectrum of tricyclopropylsilane was recorded in the R‐band region, and AM1 semi‐empirical calculations were aslo undetaken for this molecule. Both the spectroscopic data and the theoretical results indicate that tricyclopropylsilane does not exhibit any low‐energy structure having threefold symmetry. Instead, experimental evidence indicates the presence of at least two conformers of this molecule in the fluid phases, and only one of these conformers remains in the polycrystalline solid phase. The Raman and infrared spectra argue in favor of the fluid‐phase tricyclopropylsilane conformers having the three cyclopropane rings arranged in a mixture of s–cis and gauche orientations relative to the SiH bond. These conclusions appear to be corroborated by the AM1 calculations, which indicate that the cis–cis–gauche rotamer of tricyclopropylsilane is the lowest in energy, followed by the cis–gauche–gauche and cis–gauche–gauche′ conformations, which are virtually equal in energy.
Temperature‐dependent Raman study of tin(II) chloride
Authors: Kuok M. H. , Lim L. H.
Published: May 2005

The Raman spectra (10–250 cm−1) of tin(II) chloride were recorded in the range 290–10 K. The low‐temperature spectra afford better resolution and vibrational modes not previously reported were observed. These include the 18 cm−1 band which exhibits an anomalous shift of 8 cm−1 to lower frequency when the crystal temperature drops from 290 to 10 K. This band is interpreted as a lattice mode arising from the vibration of the chains of pyramidal (SnCl3) groups against one another.
Transferability of valence force constants: The case of normal fatty acid amides
Authors: Ramulu K. Sree , Rao G. Ramana
Published: May 2005

A zero‐order calculation was made for n‐undecamide and of its N,N‐deuterated species by transferring the force constants from normal fatty acid amides. The observed and calculated frequencies agreed with an average error of 11 cm−1. Potential energy distributions and eigenvectors calculated in the process were utilized to make unambiguous vibrational assignments for the two molecules under investigation.
Picosecond inverse Raman spectroscopy and sum‐frequency generation in potassium dihydrogenphosphate crystals
Authors: Jones P. F. , Jones W. Jeremy , Mallawaarachchi W.
Published: May 2005

Experiments in Raman amplification spectroscopy monitor the intensity change of one laser beam under the perturbing influence of another in a Raman‐active medium. Accompanying such changes one frequently observes the presence of other, non‐Raman, processes arising from non‐linear susceptibility terms χ(2) and χ(3), in addition to linear changes caused by species absorption and fluorescence. One such non‐Raman process observed during a Raman study of potassium dihydrogenphosphate (KDP) is sum‐frequency generation. Although the subject of second‐harmonic/sum‐and difference‐frequency generation is well understood, the indirect quantitative measurement of such processes by means of the measured power loss of one or other of the incident beams has remained an area hitherto unexplored. This paper redresses this omission by comparing experimentally the directly measured sum‐frequency power generated in a KDP frequency‐doubling crystal with the power loss of the probe beam transmitted through the crystal.

The results, viewed in an overall perspective, are very promising and the experiments demonstrate the value of the pump‐probe technique as a means of investigating non‐linear optical mixing processes, with the added advantage of an experimental set‐up which may be adapted, with the minimum of adjustments, to accommodate simultaneous investigations of several other spectroscopic processes occurring within the same system. These studies provide an interesting and important route for the further understanding and utilization of the non‐linear processes occurring in optical crystals such as KDP.
Niobium oxide solution chemistry
Authors: Jehng Jih‐Mirn , Wachs Israel E.
Published: May 2005

The solution chemistry of niobium oxide in alkaline and acidic oxalate solutions was investigated by Raman spectroscopy in order to determine the molecular structures of the various aqueous niobium oxide species. The aqueous potassium niobate species were studied as a function of pH from 14.5 to 0.55. Different types of niobium oxide ionic species such as Hx Nb6O (x = 0–3), Nb12O and Nb2O5 · nH2O exist in aqueous solutions, and both the solution pH and niobium oxide concentration determine the different niobium oxide ionic species. The aqueous niobium oxide ionic species are unstable at pH < 6.5, and hydrolyze and polymerize to form Nb2O5 · nH2O precipitate. In acidic solutions containing oxalic acid two niobium oxalate ionic species are present, [NbO(C2O4)2(H2O)2] and [NbO(C2O4)3], and the equilibrium between these species is dependent on the solution pH, oxalic acid concentration, niobium concentration and H+ concentration. The niobium oxalate ionic species are stable in the pH range 0.5‐3.0, and also from the Nb2O5 · nH2O precipitate at pH > 3.0. This study demonstrates the ability of Raman spectroscopy to determine directly the solution chemistry and molecular structures of niobium oxide species in aqueous solutions.
Raman and infrared spectra of the FeCl anion: Comparison of MCl4 and MCl6 vibrational frequencies
Authors: Shamir Jacob
Published: May 2005

Raman and infrared spectra, including two newly reported Raman frequencies, of the hexachloroferrate anion FeCl are presented. Comparison of the vibrational frequencies of MCl4 and MCl6 species indicates that the stretching frequencies increase with decrease in the coordination number, whereas the bending frequencies decrease. In addition, frequencies of the Cr–N vibrations of the hexacoordinated CrN6 system of the Cr(NH3) cation are also reported.
Resonance Raman study of the radical anion of 2,2′‐bipyridine in a glassy matrix at 77 K
Authors: Kawashima Hitoshi , Kato Tatsuhisa , Shida Tadamasa
Published: May 2005

The resonance Raman spectrum of the radical anion of 2,2′‐bipyridine obtained under cation‐free conditions is reported. Decisive evidence for a transoid structure is given. Force constants for the transoid radical anion were determined.
Raman and surface‐enhanced Raman scattering of violuric acid and violurate ion adsorbed on a silver electrode
Authors: de Oliveira L. F. C. , Santos P. S. , Rubim J. C.
Published: May 2005

The Raman spectra of violuric acid [2,4,6(1H,3H)‐pyrimidinetrione‐5‐oxime, H3 V] and sodium violurate (NaH2V) were investigated as solids and in aqueous solution at different pH. A tentative vibrational assignment is presented. From the Raman spectra obtained in solution it was possible to identify some characteristic Raman shifts for H3V, H2V− and HV2− (violurate dianion). The surface‐enhanced Raman (SER) spectra of the H2V− ion adsorbed on a silver electrode in borate buffer solution (pH 8.4) was also investigated. For potentials less negative than −0.5 V the H2V− anion adsorbs with the nitrogen atom of the oxime group and the oxygen atom of a neighbouring carbonyl group towards the surface. For potentials more negative the surface species undergoes reduction, with the oximate group ( NO−) being reduced to form an NH2 group. The SER spectra of this new species are enhanced for potentials more negative than −0.7 V.
Raman spectroscopic analysis of the effect of polyhydric alcohols on water
Authors: Auzanneau I. , Combes D. , Zwick A.
Published: May 2005

Raman spectral examinations of water‐alcohol interactions with various types of polyhydric alcohols at different levels of concentration were conducted. The parameters chosen for study seem to indicate that, at the concentrations used, polyols have little or no effect on the molecular structure of water. Further, the new band in the isotropic spectra of salt solutions reported for various alkali metal halides is absent from the spectra of polyhydric alcohols. It is concluded that polyols have less effect on the molecular organization of water than small but charged entities such as ions.
Vibrational spectra of the heteropolyanion sodium octatungstotetraphosphate(12−) icosahydrate
Authors: George Bini Lizbeth , Aruldhas G.
Published: May 2005

Based on group vibrations, a vibrational assignment is proposed for the (P4W8O40)12− ion in Na12P4W8O40 · 20H2O. The WO6 octahedra and the PO4 tetrahedra are found to be distorted in the crystal. Multiple bands observed for the stretching and bending modes of water are due to different strongly hydrogen‐bonded water molecules.
Infrared and Raman spectra of the cyclohexaphosphates M6P6O18 · 6H2O (M = Cs, Rb)
Authors: Abraham Sunila , Aruldhas G.
Published: May 2005

The infrared and Raman spectra of M6P6O18 · 6H2O (M = Cs, Rb) were recorded and analysed. The frequencies were assigned on the basis of characteristic vibrations of PO and POP groups. The P6O anion is found to have Ci symmetry with considerable distortion. The compounds are found to have a structure intermediate between those of chain polyphosphate and cyclic tetra‐ and trimetaphosphates. The presence of three different water molecules was observed.
Polarized infrared and Raman spectra of low‐frequency vibrations of two phases of crystalline m‐nitrophenol
Authors: Wójcik G. , Giermańska J. , Marqueton Y. , Ecolivet C.
Published: May 2005

Polarized IR spectra in the 20–400 cm−1 region and Raman spectra in the 0–200 cm−1 region were measured at room and liquid nitrogen temperature for crystals of two phases of m‐nitrophenol (mNPh). The Raman spectra of the orthorhombic mNPh crystal were measured as a function of temperature from room temperature up to 360 K for spectroscopic evidence of a phase transition. The symmetries of lattice and low‐frequency internal vibrations are discussed. The influence of decreasing temperature on the bands produced by the hydrogen bridge vibration is presented. The role of the hydrogen bond in the mechanism of the phase transition and the metastability of the monoclinic phase is discussed.
Raman phonon spectroscopic study of phase transition in o‐aminobenzoic acid crystal (II)
Authors: Chakrabarti Subhasis , Sarkar Uttam K. , Misra T. N.
Published: May 2005

Raman phonon spectroscopy in the 10–150 cm−1 shift range was used to study the phase transition in an o‐aminobenzoic acid crystal (II). At 77 K, twelve distinct phonon modes are observed whereas at 300 K the spectrum shows ten phonon bands. The temperature dependence of the phonon frequencies and band widths suggests that the crystal goes through a phase transition at ca. 200 K. The temperature dependence of the internal modes predicts that the phase transition is associated with some structural change in the phenyl ring.
Use of the laser Raman microprobe for discrimination amongst feldspar minerals
Authors: Mernagh T. P.
Published: May 2005

Raman spectroscopy was used to distinguish the individual members of the two feldspar subgroups. All feldspars were found to exhibit a characteristic, intense line between 500 and 515 cm−1 which is attributed to a mixed SiOSi (or SiOAl) bending/stretching mode. However, discrimination between the related members within each subgroup relies on the change in frequencies and band widths which occur in the external lattice modes and in the SiO stretching region. Spectra were recorded from single crystals and powders and demonstrate that the laser Raman microprobe can provide non‐destructive and rapid identification of feldspars on the microscopic scale.
On the non‐zero depolarization ratio in totally symmetric modes of molecules with cubic point group symmetry
Authors: Hecht Lutz
Published: May 2005

Imperfections in the incident laser beam polarization modulation technique in linear polarization Raman measurements are calculated on the basis of the Stokes‐Mueller formalism. An equation for the depolarization ratio in totally symmetric Raman bands of molecules with cubic point group symmetry is derived, yielding a depolarization ratio of ρ′obs. = 1.38 × 10−3 for the ν1 CCl stretching vibration in the C35Cl4 species. The comparison of the computed depolarization ratio with the smallest experimental value reported so far, ρobs. = 2.30 × 10−3, implies that recent attempts to explain the observation of a non‐zero depolarization ratio for the ν1 mode in liquid CCl4 by intermolecular interactions present in the condensed phase are less relevant than suggested.
Temperature‐dependent Raman scattering studies in ferroelastic LiCsSO4
Authors: Morell G. , Devanarayanan S. , Katiyar R. S.
Published: May 2005

Temperature‐dependent first‐order Raman scattering studies in the range 30–290 K were carried out in LiCsSO4 in order to investigate its phonon spectra in relation to the phase transitions in the crystal. Complete spectra were obtained for the z(xx)y and z(xz)y geometries. A careful analysis of the spectra shows that both the low‐ and high‐energy Raman modes exhibit variations either in frequency or intensity or both with temperature of the crystal, indicating that the D2k normal phase undergoes a transition at the Ti (202 K) and one to the commensurate phase at ca 160 K (Tc). Below the Tc, in the C2ν phase, the lattice mode at 44 cm−1 was observed to be a soft phonon with its frequency decreasing to 32 cm−1 at 30 K, indicating the possibility of a new structural phase transition of unlocking type in the crystal at a temperature Tu below 20 K. Another observation is the oscillating behaviour of Rayleigh scattering near the phase transition at the Ti.
Polarized micro‐Raman and Fourier transform infrared spectra of L‐glutamic acid
Authors: Dhamelincourt P. , Ramírez F. J.
Published: May 2005

The infrared and polarized Raman spectra of the amino acid L‐glutamic acid in the crystalline state have been recorded and measured. The data obtained have been used to propose a general assignment of the vibrational fundamentals on the intensity changes observed in the polarized Raman spectra and correlations with frequencies assigned in other amino acids and related molecules.
Polarized Raman and IR spectra of magnesium diammonium bis(hydrogen orthophosphate) tetrahydrate
Authors: Jayakumar V. S. , Rajagopal P. , Aruldhas G.
Published: May 2005

The polarized Raman and IR spectra of Mg(NH4)2(HPO4)2·4H2O and its partially deuterated polycrystalline sample were recorded and analysed. The presence of bands characteristic of HPO2−4 and DPO2−4 ions are interpreted in terms of the proton polarizabilities of the HPO2−4 and jDPO2−4 ions. The ammonium ion is free to rotate in the crystal and crystallographically distinct NH4+ ions exist. Hydrogen bonding of different groups is also discussed.
Surfactant‐aided surface enhanced Raman scattering of Ni(II) tetrasulphonate phthalocyanine in silver sol
Authors: Ha Jong‐Seo , Yoon Minjoong , Lee Minyung , Jang Du‐Jeon , Kim Dongho
Published: May 2005

Surface enhanced Raman scattering (SERS) has been used to investigate the structure, surface reaction and enhancement mechanism of adsorbed molecules on metal surfaces. However, a major limitation has been having to choose the molecules with functional groups capable of adsorbing onto metal surfaces. We report here SERS of Ni(II) tetrasulphonate phthalocyanine (Ni(II)PCS) as a result of introducing cationic surfactants like CTAB or CTAC. Ni(II)PCS does not adsorb onto a silver surface by itself and consequently does not show any SERS effect. The cationic surfactants employed here have functional groups to adsorb onto a silver surface and simultaneously interact with anionic sulphonate groups of Ni(II)PCS. Surfactant‐aided SERS would expand the range of SERS application to molecules which are not able to adsorb onto metal surfaces by themselves.
Line widths in the pure rotational Raman spectra of hydrogen and deuterium self‐broadened and broadened by foreign gases
Authors: Edwards H. G. M. , Long D. A. , Sherwood G.
Published: May 2005

The pressure‐broadening coefficients for the self‐broadened S0(0), S0(1) and S0(2) pure rotational Raman lines of hydrogen and the S0(0) to S0(4) lines of deuterium were determined experimentally over the pressure range 1–100 bar and the temperature range 90–375 K. Broadening coefficients were also determined for the same lines in hydrogen and deuterium perturbed by helium, argon, oxygen, nitrogen, carbon monoxide and hydrogen chloride over the pressure range 2–100 bar, with a partial pressure of the host gas of 1 bar and a temperature of 293 K. In addition, the S0(0) pure rotational line of deuterium broadened by carbon monoxide and nitrogen was studied over the same pressure range and a temperature range of 100–293 K. The results are discussed and compared with those of previous studies in the literature.
Polarized Raman spectra of ktioaso4 and isomorphic nonlinear‐optical crystals
Authors: Watson G. H.
Published: May 2005

Potassium titanyl orthorarsenate KTiOAsO4 (KTA) was studied by polarized Raman spectroscopy at room temperature. Group assignments were made by comparison with Raman spectra obtained from the well known isomorphs KTiOPO4 (KTP) and RbTiOPO4. The Raman features associated with vibrations of TiO bonds provide most of the scattered intensity. Splittings arising from occupation of two distinct sites by each of the AsO4 and TiO6 groups are observed. Additional evidence for a smaller distortion of the TiO6 group in KTA than in KTP is also present in the Raman spectra.
Interactions of cytidine derivatives with metals as revealed by surface‐enhanced Raman spectroscopy
Authors: Sánchez‐Cortés S. , Molina M. , García‐Ramos J. V. , Carmona P.
Published: May 2005

Surface‐enhanced Raman spectra of cytidine and cytidine 5′‐monophosphate adsorbed on copper and silver colloids were investigated. As an aid to the interpretation with regard to the metal‐adsorbate binding sites, the normal Raman spectra of the complexes of these substances with the metal ions were also obtained. The adsorption of the cytosine moiety in these substances occurs preferentially through the carbonyl bond, the pyrimidine ring adopting a non‐planar orientation on the surface. However, in the complexes involving the metal ions the N‐3 position is found to be the site through which the base interacts with these metals. The ribofuranose ring does not seem to participate significantly in the interaction of these substances with copper and silver in either the colloidal or ionic states.
Polarized infrared and Raman spectra of urea—phosphoric acid and urea—arsenic acid single crystals
Authors: Ilczyszyn M. M. , Ratajczak H. , Barnes A. J.
Published: May 2005

The polarized infrared and Raman spectra of single crystals of urea—phosphoric acid, (NH2)2CO · H3PO4, its deuterated analogue, (ND2)2CO · D3PO4, and urea—arsenic acid, (NH2)2CO · H3AsO4, were measured. The results obtained are discussed on the basis of the crystal structure and the selection rules. Characteristic spectral features due to hydrogen bond vibrational modes were identified, from their polarization behaviour, as arising from the very short, almost symmetrical O …︁ H …︁ O hydrogen bond connecting the urea and phosphoric (or arsenic) acid molecules and from two other strong OH …︁ O hydrogen bonds, linking different adducts.
Vibrational spectroscopic study of the three solid phases of bicyclo[2.2.2]octene
Authors: Kawai Nancy T. , Butler Ian S. , Gilson Denis F. R.
Published: May 2005

The three solid phases of bicyclo [2.2.2] oct‐2‐ene were characterized by vibrational spectroscopy at low temperatures and high pressures. Bicyclooctene undergoes a phase transition at 176 K on cooling (phase I → phase II) and then another at ca 95 K (phase II → phase III). On compression at room temperature, these same transitions occur at 7.9 ± 1.0 kbar and ca. 15 kbar. The low‐frequency Raman spectra show that phase I is isotropically disordered, whereas phase II is anisotropically disordered. The crystal structure of phase II is, however, similar to that of phase III, and is suggested to be tetragonal.
Raman spectra of Pb1–3x Bi2x MoO4 (x ⩽ 0.06) and their 18O‐substituted systems
Authors: Kanesaka Isao , Kirishiki Masaru , Matsuura Ikuya
Published: May 2005

A new band at 896 cm−1 is ascribed to a local mode, v1, due to a molybdate ion occupying a cation vacancy. Local modes for v3 and v4 were also found at ca. 800 and 397 cm−1, respectively. The relative intensity for translational modes at 71 and 59 cm−1 varied considerably with x. This was explained in terms of a decrease in primitive cells with two Pb2+ ions. The band decomposition was carried out for the v1 region in 18O‐substituted systems. The equilibrium distribution for isotopic species, [Mo16O4‐n18On]2− (n=0‐4). was found approximately in the system with x = 0.01 after annealing, whereas the discrepancy between the observed and equilibrium distributions increased with increase in x. These observations show that a molybdate ion interacting strongly with a Bi3+ ion and a cation vacancy is inactive for 18O‐substitution.
Raman study of the phase transition in CsSnCl3
Authors: Kuok M. H.
Published: May 2005

The polarized Raman spectrum of CsSnCl3 single crystals was studied as a function of temperature between 10 and 400 K. When heated above 385 K the crystals transform from the monoclinic to the cubic perovskite phase, and the Raman data suggest that the phase transition is first order. No soft mode was observed. No further signs of any structural phase transitions were found on cooling the crystals to 10 K. Several Raman bands were assigned to the correlation‐field split components of the funadmental vibrations of the pyramidal SnCl ion.
Raman and infrared spectra, conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment for vinyl fluoroformate
Authors: Durig J. R. , Lin Jie , van der Veken B. J.
Published: May 2005

The Raman spectra (3200—10 cm−1) and infrared spectra (3500—50 cm−1) of vinyl fluoroformate, H2CCHOC(O)F, were recorded for both the gas and solid. Additionally, the Raman spectrum of the liquid was recorded and depolarization ratios were obtained. These data have been interpreted on the basis that the only stable conformation present at ambient temperature is the trans‐trans, where the first trans refers to the vinyl moiety relative to the OCFO bond and the second trans to the CF bond relative to the CO bond. Anharmonic rigid asymmetric top calculations were used to predict the CO and CC stretch infrared vapor‐phase contours for the trans‐trans and the cis‐trans conformers. For both conformers, the predicted CO stretch contour agrees with the experimentally observed contour. For the CC stretch, only the contour predicted for the trans‐trans conformer reproduces the experimental contour. From the far‐infrared spectrum of the vapor obtained at a resolution of 0.1 cm−1, the methoxy and O‐vinyl torsional fundamentals have been observed at 153 and 63 cm−1, respectively. The structure, barrier to internal rotation and vibrational frequencies were also determined from ab initio Hartree‐Fock gradient calculations using both the 3—21G and 6—31G* basis sets. These results are compared with theos obtained experimentally and to similar quantities for some related molecules.
Raman spectroscopy of potassium selenate at high pressure
Authors: Yenice K. M. , Lee S. A.
Published: May 2005

The pressure dependence of the vibrational modes of potassium selenate was measured via Raman spectroscopy up to 7 GPa at room temperature. The force constants internal to SeO ‘free’ radical were calculated as a function of pressure from these data.
Raman and hyper‐Raman tensors for point groups with eightfold rotation axes
Authors: Jiang Yi‐Jian , Liao Li‐Ji , Chen Gang , Zhang Peng‐Xiang
Published: May 2005

Using a new method, the Raman and hyper‐Raman tensors for the point groups 8 (C8), 8 (S8), 8/m (C8h), 8mm (C8ν), 822 (D8) and 8/mmm (D8h) have been tabulated.
Some comments on ‘quenching of stimulated Raman scattering by two‐photon absorption in fuels’
Authors: Jones W. Jeremy
Published: May 2005

A recent paper by Golombok et al. in this Journal provides an explanation for the appearance in stimulated Raman scattering from certain aromatic liquids of oscillation on many Raman modes in place of the single Raman mode that generally dominates such spectra; this explanation is based on two‐photon absorption of the resulting Raman radiation. It is suggested in this paper that this process, although undoubtedly significant, is not the dominant process in suppressing completely oscillation on certain strong, sharp Raman transitions which would be expected to dominate the spectra. Of greater significance in suppressing such oscillations will be sum‐photon absorption with one photon being absorbed from each of the incident laser and the Stokes‐shifted Raman radiation. Calculated growth curves of the Raman radiation generated show that this process has the correct functional dependence to prevent Raman oscillation totally whereas two‐photon absorption of the Raman radiation created can only limit, but not totally suppress, the growth of the first Stokes wave.
Vibrational spectra and conformations of 1, 4‐dibromobut‐2‐yne and 1,4‐diiodobut‐2‐yne
Authors: Karlsson A. , Bauza G. D. , Klaeboe P. , Nielsen C. J. , Sülzle D.
Published: May 2005

The Raman spectra of 1,4‐dibromobut‐2‐yne (BrBr) as a liquid at various temperatures and as an amorphous and crystalline solid at low temperatures were recorded in the 3200‐10 cm−1 region. IR spectra of the liquid at room temperature and of the amorphous and crystalline solids at low temperatures (4000‐50 cm−1) were obtained. Additional IR spectra of the vapour were recorded (4000‐500 cm−1). The spectra of the liquid phase showed characteristic, broad bands below 500 cm−1. No temperature dependence was detected in these, and the spectra of the amorphous solid at 90 K are almost identical with the room temperature spectra of the liquid. A shoulder on the Rayleigh line was observed at ca. 20 cm−1 in the Raman spectrum of the amorphous BrBr at 90 K which tentatively, has been interpreted as the torsional mode. In the crystal an anti conformer was present, while the spectra of the vapour and the liquid were interpreted in terms of large torsional freedom. The Raman and IR spectra of the very unstable 1,4‐diiodobut‐2‐yne (II) as a crystalline solid were recorded in the 4000‐20 cm−1 range at low temperatures. Spectra of carbon disulphide solutions at temperatures 250–260 K were obtained and additional IR spectra of II in Nujol mulls and in KBr pellets were also recorded. In the region below 500 cm−1, Where other 1,4‐dihalobut‐2‐ynes have characteristic, broad bands, a high irregular background was observed in the Raman spectrum of II in solution. The spectra agree with an anti conformer present in the crystal and nearly free internal rotation in the liquid. The vibrational assignments are supported by force constant calculations and by a correlation diagram for the vibrations of the six skeletal bending modes in 1,4‐dichlorobut‐2‐yne, BrBr and II.