bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractSurface‐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

AbstractA 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

AbstractRaman 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

AbstractStrong 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

AbstractGas‐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

AbstractThe 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

AbstractThe 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

AbstractHigh‐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

AbstractIR 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

AbstractA 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

AbstractThe 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

AbstractRaman 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

AbstractIR 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractExperiments 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

AbstractThe 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

AbstractRaman 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

AbstractThe 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

AbstractThe 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

AbstractRaman 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

AbstractBased 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

AbstractThe 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

AbstractPolarized 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.