bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman spectroscopic study of the thermal and catalytic decomposition of butane
Authors: Brogan Mark S. , Cairns James A. , Dines Trevor J.
Published: May 2005

The products of the thermal decomposition of butane at temperatures up to 600 °C were identified by Raman spectroscopy. Heating to 500 °C resulted in the formation of a number of hydrocarbon products, in accordance with established reaction mechanisms. Heating to 600 °C, however however, led to methane as the sole product. By contrast, heating in the presence of either Al2O3 or PtAl2O3 yielded a different product distribution, attributed to interaction with Lewis acid sites on the Al2O3 surface. The Raman results were compared with data obtained by GC analysis.
Raman spectra of Cu(HCO2)2 · 4H2O in the region of OH stretches at room temperature
Authors: Kanesaka Isao , Kuwano Kazuhiko
Published: May 2005

Polarized Raman spectra of Cu(HCO2)2 · 4H2O (CFT) and 5% deuterated CFT were observed at room temperature in the region of the OH and the decoupled OD stretches, respectively. The analysis of the decoupled OD stretches clarified the wavenumbers for seven OD sites in the two‐dimensionally hydrogen‐bonded network. In the polarized Raman spectra of CFT it was found that the polarized spectra parallel and perpendicular to the six‐membered hydrogen‐bonded ring differ greatly; the parallel spectrum corresponds well to that the ice Ih. The strong band in the perpendicular spectrum is explained in terms of the uncoupled stretches due to the OH groups which do not participate in the six‐membered ring. These spectra were analysed using 72 water molecules with disorder to the hydrogen positions which satisfy a periodic boundary condition. It was found that the observed Raman spectra are approximately explained in terms of the initial set of force constants. The Raman spectrum of deuterated CFT in the polycrystalline state could also be simulated well.
Raman and infrared spectra, conformational analysis, ab initio calculations and vibrational assignment of 3‐bromopropionitrile
Authors: Durig J. R. , Guirgis Gamil A. , Drew A. S.
Published: May 2005

The Raman (3200—10 cm−1) and infrared (3100—400 cm−1) spectra were recorded for liquid and solid 3‐bromopropionitrile, BrCH2CH2CN. These data are interpreted on the basis that the molecule exists as a mixture of trans (Br atom oriented trans to the CN group) and gauche conformers in the liquid phase with the gauche form the more stable rotamer and the only conformer in the solid. From variable‐temperature Raman studies of the liquid, the enthalpy difference between conformers was determined to be 434 ± 19 cm−1 [(1.24 ± 0.05 kcal mol−1) (1 kcal = 4.184 kJ)]. A complete vibrational assignment is proposed for both conformers. Ab initio calculations were performed employing the RHF/LANL1DZ basis set to obtain the structural parameters, barriers to internal rotation, the fundamental wavenumbers for both conformers and the infrared and Raman intensities. The calculated values are compared with the corresponding experimental quantities. These results are discussed and compared with similar quantities obtained for some related molecules.
Raman spectra and isomerism of some chlorophenylphosphoranes (C6H5)nPCl5 — n (1 ≤ n ≤ 3) and their lewis acid salts
Authors: Al‐Juboori Mohammad A. H. A. , Gates Peter N. , Muir Alan S.
Published: May 2005

Syntheses of stable and metastable isomers for each of the chlorophenylphosphoranes, PhPCl4, Ph2PCl3 and Ph3PCl2, together with some Lewis acid salts are described. Comparison of Raman spectra of the salts with one set of isomers suggests an ionic formulation [PhnPCl] [Cl−] (1 ≤ n ≤ 3); correlation with spectra of Sb and As analogues of known structure suggest pseudo‐trigonal bipyramidal (Ψtbp) structures for the other isomers. Thermodynamically stable isomers are ionic Ph3PCl+Cl−, Ψtbp Ph2PCl3 and Ψtbp PhPCl4. Vibrational Raman assignments for the skeletal modes are given for each of the isomers and some of their Lewis acid salts. Frequency shifts arising from non‐bonded interactions in the ionic species are compared with those in the methyl‐substituted analogues.
SERS of cytosine and its methylated derivatives on gold sols
Authors: Camafeita L. E. , Sánchez‐Cortés S. , García‐Ramos J. V.
Published: May 2005

SERS spectra of cytosine, 1‐methylcytosine, 5‐methylcytosine and 1,5‐dimethylcytosine on a gold colloid are reported. A tentative assignment of Raman bands is made by comparison with the normal Raman spectra in aqueous solution. This analysis reveals a preferred non‐planar orientation of cytosine and 1‐methylcytosine and a more planar orientation of 5‐methylcytosine and 1,5‐dimethylcytosine with respect to the metal surface, the C=O group being determinant in the interaction. A comparative study using the result obtained previously using silver and copper colloids as supports shows important differences in the electrodynamic behaviour of these molecules which depend on the presence of the methyl substituents and the nature of the metal on which they adsorb.
Vibrational relaxation processes in isotropic molecular liquids. A critical comparison
Authors: Morresi A. , Mariani L. , Distefano M. R. , Giorgini M. G.
Published: May 2005

Dynamic processes in the liquid state can be examined from different points of view; the rapid development of highly sophisticated time‐resolved experiments and very complex computer simulation techniques have certainly improved the accuracy of some laboratory results, but they are often not followed by an adequate attempt at interpretation. In any case, the extent of the subject and the enormous spread of experimental data do not help systematic analysis.

This review attempts to contribute to a critical examination of a particular aspect of the dynamics of the liquid phase. Through a study of vibrational relaxation in isotropic molecular liquids it is possible to gain information about the molecular environment and the main intermolecular forces operative in this state of matter. It is therefore possible to formulate hypotheses about the force potentials and to describe the dynamic regime of the liquid system under consideration.

At present, we may single out four groups of molecues that have been investigated by these methods:

(1) diatomic and/or highly symmetric molecules (e.g. HCI, O2, CH4);

(2) derivatives of hydrocarbons, especially methane (e.g. CH3NO2, CHCl3, CH2Cl2);

(3) aromatic and cyclic aliphatic molecules (e.g. benzene and its derivatives, cyclohexane, pyridine);

(4) hydrogen bonded (with OH and/or HCO groups).

This paper concerns the comparison between vibrational motions that have similar normal coordinate descriptions; for this reason, we shall limit our considerations to the second and third groups in the above list. Hydrogen‐bonded and highly symmetrical systems are excluded because they need specific considerations.

The currently used basic nomenclature of this field will be illustrated, in addition to the physical meaning of the dynamic parameters usually obtained by steady‐state (continuous Raman and infrared), time‐resolved spectroscopy and computer simulation techniques; these different experimental data will be compared, when available. We shall also outline and discuss current theoretical models, and attempt to emphasize their potential and limitations.
Surface‐enhanced Raman spectroscopic studies on silver electrodes in the presence of 2‐mercaptopyrimidine
Authors: Li W. H. , Mao B. W. , Tian Z. Q.
Published: May 2005

Surface‐enhanced Raman spectroscopy (SERS) was applied to the study of silver electrodes in the presence of 2‐mercaptopyrimidine (2MP) over a wide electrode potential range from —0.3 to —1.8 V (vs. SCE). The spectra reveal that in neutral solution 2MP was adsorbed perpendicularly on the silver electrode via its sulphur atom at potentials more positive than — 1.1 V and was electrochemically reduced at more negative potentials. The significant dependence of the SERS spectra on the solution pH and the time‐resolved SERS results suggest that hydro‐oligomerization of 2MP may take place during the electrochemical reduction process. It has been shown that SERS can be used as a unique tool to study structural changes of electrochemical interfaces through detailed molecular level analyses in the electrode potential region of hydrogen evolution.
Structure and IR and Raman polarized spectra of BaLaGa3O7 single crystals
Authors: Hanuza J. , Hermanowicz K. , Maczka M. , Ryba‐Romanowski W. , Lis T. , Berkowski M.
Published: May 2005

X‐ray diffraction analysis was applied to a BaLaGa3O7 single crystal obtained by the Czochralski technique. It crystallizes in the tetragonal system with the space group P421m (D) and two formula units in the unit cell of dimensions a = 8.145 (2), c = 5.382 (2) Å at 300 K. Polarized IR transmission and Raman scattering spectra of oriented single crystals were measured and are discussed in terms of factor group analysis and x‐ray structure. A vibrational assignment is proposed.
Vibrational study of the structure and polarons in piperazine hexahydrate
Authors: Kanesaka Isao , Kuwano Kazuhiko , Ishioka Tsutomu
Published: May 2005

The Raman spectrum of piperazine hexahydrate was observed over the whole wavenumber region at various temperatures (300—29 K). The splitting between the N—H stretch and the polaron was found to be 21 cm−1 at 44 K. The bands due to the axial configuration of piperazine were above 200 K in both the H and D systems. The enthalpy difference in the equatorial—axial equilibrium was calculated to be 8.1 and 7.6 kJ mol−1 in the H and D systems, respectively. The phase transition was found at ca. 170 K, and is ascribed to the order—disorder type associated with the axial configuration. The polaron was discussed group theoretically and reinvestigated on the basis of the coupling of the N—X stretch with optical lattice modes. It is noted that the polaron is little affected by the phase transition at 170 K or disorder in hydrogen positions.
Resonance Raman spectroscopy of rhodizonates: Evidence of low‐energy transitions in the solid state
Authors: Gonçalves Norberto Sanches , Santos Paulo Sergio
Published: May 2005

The optical and Raman spectra of several salts of rhodizonic acid were investigated, aimed at a better understanding of the dramatic dependence of their colours on the nature of the cation. The results indicate that in addition to the maxima observed in the optical spectra, another transition in the red edge must be present in the solid state, as indicated by the large number of overtones and combination bands in the Raman spectra excited in the red. It is suggested that such a low‐energy transition observed only in the solid state is of intermolecular origin, as observed previously for other related systems.
Determination of the molecular structures of tungstates by Raman spectroscopy
Authors: Hardcastle Franklin D. , Wachs Israel E.
Published: May 2005

An empirical correlation is developed for relating the wavenumbers of (WO) stretching modes to WO bond lengths and bond strengths for tungsten oxide reference compounds. A least‐squares exponential fit of crystallographically determined WO bond lengths to the wavenumbers of their Raman stretching modes is presented along with a relation between WO bond strengths, in valence units, and wavenumbers of Raman stretching modes. The empirical bond length/stretching mode wavenumber/bond strength relationships lead to a unique and effective method of interpreting Raman spectra of tungstate species. This method leads to the WO bond lengths and coordination of the tungstate species. The utility of the method is illustrated by estimating the wavenumbers of the Raman stretching modes for the ideal WO4 tetrahedron and WO6 octahedron, and the bonds lengths and coordinations of the tungstate species in the reference compounds Na2WO4, PbWO4, CaWO4 and Bi2WO6. In addition, the WO bond lengths of the WO6 octahedra in crystalline Ba2MgWO6 are reported for the first time. This new approach for evaluating the Raman spectra of tungstate species is expected to be generally applicable to all tungstates, regardless of environment, physical state, or oxidation state.
Use of micro Raman spectroscopy for the quantitative determination of polyethylene density using partial least‐squares calibration
Authors: Williams K. P. J. , Everall N. J.
Published: May 2005

A series of polyethylene samples were analysed using a micro Raman system. The data were analysed using a commercial partial least‐squares package and correlated with the polymer density. A correlation coefficient of up to 0.98 was obtained, depending on the spectral region used. A standard error of prediction of 2.15 kg m−3 was obtained and the densities of ‘blind’ samples were predicted with good accuracy.
Fourier transform Raman spectroscopy of nitrogen at high pressures
Authors: McNesby Kevin L. , Morris Jeffrey B.
Published: May 2005

Ro‐vibrational and rotational Raman spectra of nitrogen gas at 300 K over the pressure range 3‐24 MPa (500‐3500 psi) were measured using a Fourier transform spectrometer employing 1064 nm laser radiation as the scattering source. It is shown that the pressure‐induced narrowing and peak shift of the Raman spectrum of N2 observed in these experiments agrees within experimental error with data obtained by other workers using different techniques.
Temporally two‐dimensional Raman spectroscopy of liquids by six‐wave mixing with ultra‐short pulses
Authors: Tominaga Keisuke , Keogh Gary P. , Naitoh Yukito , Yoshihara Keitaro
Published: May 2005

A temporally two‐dimensional Raman spectroscopic method was developed to observe the fifth‐order optical response of liquids. Taking advantage of temporal two‐dimensionality, this technique can unambiguously distinguish homogeneous and inhomogeneous contributions to the dephasing of low‐wavenumber vibrational modes. The measurement of the fifth‐order optical response of liquid CS2 was conducted by ultra‐fast non‐resonant six‐wave mixing using five different pulses. The experimental results are reproduced well in terms of one overdamped mode in the homogeneous limit and one underdamped mode with the width of the inhomogeneity less than 2.5 ps−1.
Ultrafast Raman echo experiments in liquids
Authors: Bout David Vanden , Berg Mark
Published: May 2005

The Raman echo is the first of the eight‐wave mixing spectroscopic techniques to be experimentally demonstrated in molecular systems. Practical results achievable in such high‐order experiments are described. Signal levels, competing non‐linear effects, phase‐matching requirements and other experimental design considerations are discussed. Results needed to predict the success of experiments at different power levels, Raman cross‐sections and concentrations are presented.
Femtosecond inverse Raman spectrum of molecular J‐aggregates
Authors: Misawa Kazuhiko , Minoshima Kaoru , Kobayashi Takayoshi
Published: May 2005

The femtosecond inverse Raman spectrum of J‐aggregates of a cyanine dye was studied theoretically and experimentally by the pump—probe experiment. The time dependence of the Raman signal intensity of the aggregates was fitted with an instantaneously responding component due to the Stark effect together with 200 fs and 1 ps lifetime components due to the excitons. The instantaneous response in the time‐resolved difference transmission spectrum including the inverse Raman, induced and saturated absorption was successfully reproduced by the calculation under sub‐resonant excitation based on the density matrix formalism.
Raman, infrared and 13C NMR studies of mixed halides of cyclopropene, C3ClnBr4—n, and cyclopropane, C3ClnBr6—n
Authors: Taylor Michael J. , Baker L.‐J.
Published: May 2005

Tetrachlorocyclopropene, C3Cl4, is converted into C3Br4 by treatment with BBr3. Use of less than the stoichiometric amount of BBr3 leads to mixed halides C3ClnBr4‐n which are identified and investigated by Raman and 13C NMR spectroscopy. The addition of Br2 to C3Cl4 yields both the isomers cis‐ and trans‐1,2‐dibromotetrachlorocyclopropane in equal quantities; the vibrational spectra are reported and partially assigned. Raman and 13C NMR of other mixed halides of cyclopropane, C3ClnBr6‐n are discussed. A 35Cl/37Cl isotope effect is detected on the carbon chemical shift of C3Cl6 I2 fails to react with C3Cl4 or C3Br4.
Resonance Raman studies of heterocyclic aromatic compounds showing ultrafast intramolecular proton transfer
Authors: Pfeiffer M. , Lenz K. , Lau A. , Elsaesser T.
Published: May 2005

Resonance Raman spectra of the three isoelectronic proton transfer systems 2‐(2′‐hydroxy‐5′‐methylphenyl)‐benzotriazole (TIN), 2‐(2′‐hydroxyphenyl)benzothiazole (HBT) and 2‐(2′‐hydroxyphenyl)benzoxazole (HBO) were measured with excitation in the range of the S0‐S1 absorption band of the enol tautomers. In each compound, about 15 modes in the wavenumber range between 120 and 1650 cm−1 show a strong coupling to the electronic transition. In TIN and HBT, combination tones of the strongest mode below 500 cm−1 and the vibrations at higher wavenumbers point to the strong anharmonicity of the low wavenumber motion. The experimental results are analysed by normal‐mode calculations, which provide insight into the microscopic elongations in the molecules. The coupling strengths derived from the spectra are used to calculate the envelope of the S0‐S1 absorption bands of TIN and HBT, reproducing the measured spectra very well. Theoretical simulations of the combination tone spectra give information on the vibrational modes involved in excited‐state proton transfer.
SERS of dicarboxylic acids on silver sols
Authors: Arenas J. F. , Castro J. L. , Otero J. C. , Marcos J. I.
Published: May 2005

SERS spectra of succinic and oxalic acids on silver sols have been revised. For the latter molecule the vibrational spectrum has been assigned on the basis of AM1 and 3‐21G ab initio force field calculations. Also, SERS of the malonate ion is presented for the first time, showing some general characteristics similar to the aforementioned. The results have been analysed together, and a model is proposed in which the interaction with the surface is through one carboxylate group in the case of oxalic acid and through both carboxylate groups in the case of malonic and succinic acids.
High‐resolution Raman spectra of the Fermi diad in disordered crystalline CO2
Authors: Andueza J. J. , Ouillon R. , Lucarre J. P. Pinan , Ranson P.
Published: May 2005

Using high‐resolution Raman spectroscopy, very weak features in the biphonon spectra of disordered materials were investigated. The analysis was focused on the bound states due to the Fermi resonance in crystalline CO2. Two systems were studied: the mixed isotpic (12CO2)x—(13CO2)1−x crystals and the molecular alloys (N2O)x—(12CO2)1− x and (N2O)x—(13CO2)1− x. In the first system, it was shown that the wavenumbers and bandwidths of biphonon states at K ≈︁ O follow a concentration dependence identical with that encountered for one‐phonon states which obey the separated band limit model in mixed isotopic crystals. In the second system, the occurrence of a fine structure in the biphonon band is discussed on the basis of a strong interaction between non local matrix biphonons and quasi‐local biphonons created by the disorder.
Raman spectra, conformational stability and normal coordinate analysis of ethylmethylamine
Authors: Batista De Carvalho L. A. E. , Teixeira‐Dias J. J. C.
Published: May 2005

Raman spectra of ethylmethylamine and ethylmethylamine‐N‐d, both in the liquid phase, at different temperatures, and in the solid phase were recorded. Additionally, Fourier transform IR (4000—400 cm−1) spectra of these compounds in the liquid phase were also obtained. Normal coordinate calculations were performed for each conformer (T, G and G′), using an optimized local symmetry force field for secondary amines. These calculations allowed the assignment of the vibrational spectra, in good agreement with the experimental evidence. Whereas in the liquid phase all the three possible conformers were detected, in the solid phase only the bands ascribed to the T conformer were observed. From the temperature dependence study of the Raman spectrum of the liquid, the enthalpy differences between conformers were determined, yielding the values 4.6 ± 0.3 kJ mol−1 for ΔHG′‐T′ 3.6 ± 0.3 kJ mol−1 for ΔHG ‐ T and 1.1 ± 0.3 kJ mol−1 for ΔHG′‐ G. These were compared with ab initio SCF‐MO results, for the isolated molecule, in order to assess the relative importance of intra‐and intermolecular effects on conformational equilibria.
Dependence on concentration and temperature of the dynamics of SO in Li2SO4, Na2SO4 and K2SO4 aqueous solutions studied by Raman spectroscopy
Authors: Rull F. , Sobrón F. , Nielsen O. F.
Published: May 2005

The Raman spectra of the v1(SO) band in aqueous solutions of Li2SO4, Na2SO4 and K2SO4 as a function of concentration at room temperature and for fixed concentrations in the temperature range 5—85°C were studied. It was found that the molar scattering coefficient for SO is virtually independent of the concentration and temperature in the studied range. Nevertheless, the v1(SO) band shows some asymmetry on the high‐wavenumber side for Li and Na and on the low‐wavenumber side for K, which for these last two cases has not previously been reported. Moreover, the band position seems to be correlated with the sign and amount of the asymmetry as the concentration increases. On the other hand, temperature does not have a great effect on the band profile. In the case of Na and K, there is little narrowing of the band, whereas for Li there is slight broadening and an increase in the asymmetry. Quantitative analysis of these changes was performed using the vibrational correlation function. This was modelled considering the distribution of sulphate oscillators in the aqueous media as a convolution product of an unperturbed distribution by a perturbation function. This last function assumes a feedback mechanism in which the main parameters are the coupling energy and the fraction of the distribution having interactions. The dependence of these parameters and of the Gaussian and Lorentzian contributions to the band profile with concentration and temperature are discussed.
Raman and infrared intensities in trimethylamine species, polarizability and dipole derivatives and effective charges
Authors: Murphy W. F. , McKean D. C. , Coats A. M. , Kindness A. , Wilkie N.
Published: May 2005

Raman trace scattering intensities are reported for the d0, d3, d6, d8 and d9 deuterated species of trimethylamine. Using normal coordinates from a previous scaled ab initio force field, the data are analysed in terms of seven derivatives ∂α¯∂S in the A1 symmetry species, each of which is well defined. Similar derivatives (dα¯/dr)CH with respect to the stretching of the two kinds of CH bond are shown to be very different from each other, showing a marked effect of the lone pair. Infrared intensities were measured for the d0, d8 and d9 species. These are well reproduced by ab initio calculations at the MP2/6‐31G* level. The dipole derivative for the CHS bond trans to the lone pair is much greater than that for the Ha bond in the gauche position. The ab initio atomic polar tensors were used to obtain effective charges and other invariants, and the directions of dμ/dr for the CH bonds were determined. That for the Hs bond lies 23° off the bond direction. The ratio Xa/Xs of the abundances of the Ha and Hs conformers in the d8 isotopomer, required for the above analyses of the spectra, is calculated to be 1.80(4).
Stochastic model for correlation functions from anisotropic Raman line shapes
Authors: Ribeiro Mauro C. C. , Santos Paulo S.
Published: May 2005

The separation of the Raman correlation function as a product of independent vibrational and reorientational correlation functions is investigated. The present model is a unification of previous models which treat separately vibrational dephasing and reorientational relaxation within the context of the stochastic approach. It indicates that the so‐called product approximation for the Raman correlation function can fail even when the relaxation rate is distinct for vibrational and reorientational relaxations. Application to experimental data for liquid CS2 is presented.
Resonance Raman spectroscopic studies of pH indicators adsorbed on γ‐Al2O3
Authors: Bisset Alison , Dines Trevor J.
Published: May 2005

Resonance Raman spectra were recorded from methyl red, ethyl red and α‐naphthyl red adsorbed from toluene solutions on to γ‐alumina. The spectra show clear evidence for the protonation of all three indicators. Adsorption data over a wide range of equilibrium concentrations give satisfactory fits to Langmuir isotherms. Together with the spectroscopic data, the isotherms permit the determination of the densities of Brønsted acidic sites on the γ‐alumina surface. The densities of acidic sites decrease after calcination at 300°C.
Vibrational and rotational spectra, conformations and ab initio calculations of thiocyanatoethene
Authors: Beukes J. A. , Klaeboe P. , Møllendal H. , Nielsen C. J.
Published: May 2005

Infrared spectra of thiocyanatoethene in the 4000‐400 cm−1 region in the vapour and liquid states and of the amorphous and crystalline solids at low temperatures were obtained. Additional IR spectra of the compound were recorded when isolated in argon and nitrogen matrices at 5 K using the hot nozzle technique. Raman spectra in the liquid phase at various temperatures were recorded and the amorphous and crystalline solids were investigated at liquid nitrogen temperature. Microwave spectra of thiocyanatoethene were recorded in the 10‐39 GHz region by means of Stark modulation. Areas of special interest were also investigated by use of the RFMWDR double resonance technique. Ab initio quantum chemical calculations were carried out with the 6—31G* basis set.

The spectral data were interpreted in terms of an equilibrium in the vapour and liquid states between a syn and a gauche conformer, while syn was the only conformer present in the crystal. An approximate enthalpy difference of 3—6 kJ mol−1 in the vapour and 5.7 ± 1.0 kJ mol−1 in the liquid was determined, with the syn conformer being the more stable. The microwave spectrum of the syn conformer was assigned, giving rotational constants in good agreement with the results of the ab initio calculations, whereas we were not able to assign unambiguously the spectrum of the gauche conformer. The internal energy difference between the syn and gauche conformers was determined to be 4.4 ± 1.0 kJ mol−1.
KSbF6 revisited. I—A Raman and infrared study of the tetragonal phase I
Authors: Heyns Anton M. , van den Berg Magda M.
Published: May 2005

The polarized Raman spectra of single crystals of KSbF6‐I of P42m‐D symmetry are reported. The predicted LO‐TO splittings of the B2 and E modes were not observed and the vibrational spectra do not indicate a non‐centrosymmetric structure. The calculated relative intensities of the Raman bands in the single‐crystal spectra agree very well with the observed values. It is shown that the anions execute fourfold reorientational motions around the S4 axis of the crystals and an activation energy of 3.2 kcal mol−1 (13.4 kJ mol−1) is calculated from the variation of the linewidths of Raman bands with temperature. The barrier is penetrated by the anions and because of the jumping motions of the anions in KSbF6‐I the small distortions from a centrosymmetric structure are averaged out and the Raman and infrared spectra appear to be mutually exclusive.
Raman and infrared spectra, ab initio calculations and normal coordinate analysis of boranedimethyl sulfide
Authors: Chatterjee K. K. , Durig J. R.
Published: May 2005

The Raman spectra (3200‐40 cm−1) of liquid and solid boranedimethyl sulfide, (CH3)2SBH3, were recorded and depolarization data were obtained from the liquid. Additionally, the infrared spectrum (3200‐400 cm−1) of the liquid was obtained. A complete vibrational assignment is proposed based on depolarization data, group wavenumbers and relative intensities and it is supported by normal coordinate calculations. Ab initio calculations were carried out employing the RHF/3‐21G*, RHF/6‐31G* and MP2/6‐31G* basis sets to obtain the structural parameters, the fundamental wavenumbers and the intensities of the infrared bands. The calculated values are compared with the corresponding experimental quantities. The results are discussed and compared with similar quantities for some related molecules.
Raman optical activity of enantiomorphic single crystals
Authors: Lindner M. , Schrader B. , Hecht L.
Published: May 2005

Conventional Raman and incident circular polarization Raman optical activity (ROA) spectra are presented for the lattice vibrations of enantiomorphic pairs of optically active cubic crystals NaBrO3 and NaCIO3 in depolarized right‐angle scattering (65‐145 cm−1) and unpolarized backscattering (55‐200 cm−1). Since enantiomorphic cubic crystals are also piezoelectric owing to the lack of a centre of inversion, the degeneracy of their triply degenerate polar (infrared and Raman active) F phonons is partially lifted because of long‐range dipole‐dipole interactions. Therefore, non‐degenerate longitudinal and doubly degenerate transverse optical phonons can be separately observed in the ROA spectra.
Study of polarization CRS and polarization ICRS with application to benzena
Authors: Schaertel S. A. , Lee Duckhwan , Albrecht A. C.
Published: May 2005

Passage from the microscopic third‐order optical polarizability tensor to the macroscopic third‐order susceptibility tensor elements in coherent Raman scattering (CRS: CARS and CSRS) is reviewed with appropriate orientation averaging for an isotropic medium. The results are applied to existing polarized CARS measurements for the 991 cm−1 vibration in benzene as a neat liquid [M. D. Levenson and N. Bloembergen, J. Chem. Phys. 60, 1323 (1974)] and also to new polarized interferometric data on the same system from a method called interferometric coherent Raman spectroscopy (ICRS; ICSRS in particular is used). Lineshape analysis of the CARS spectra seen in both the ZXXZ polarization (mildly dispersive) and the ZZZZ polarization (strongly dispersive) leads to ratios for the non‐resonant to resonant parts of the corresponding susceptibility elements. Thus X/X = 0.5 (from 0.3‐1.7) (a new result) and X/X = 0.042 + 0.002 (from Levenson and Bloembergen). It is shown that given one ratio, the second must be completely determined by the depolarization ratio from conventional Raman scattering. These same tensor element ratios are incorporated into ICSRS theory to produce polarized interferograms which qualitatively confirm the strikingly different patterns seen in the ZXXZ and ZZZZ polarized ICSRS experiments. On the quantitative level, agreement is less satisfactory.
Raman spectroscopic studies of silk
Authors: Edwards H. G. M. , Farwell D. W.
Published: May 2005

The Fourier transform Raman spectra of silk at several stages of its processing from raw natural and cultivated cocoons to woven fabric were obtained. The application of near‐infrared excitation to the recording of quality Raman spectra from bulk samples, including Russian and Chinese varieties, and from a single 10 μm fibre is demonstrated. Comprehensive vibrational assignments are made for silk and comparisons are made of wild and cultivated silks, bleached and unbleached de‐gummed varieties and inner and outer cocoon material.
Surface‐enhanced Raman spectroscopic investigations of thiazole orange derivatives using visible and near‐infrared excitation
Authors: Nissum M. , Nielsen O. Faurskov , Jensen F. , Jensen P. Waage
Published: May 2005

Surface‐enhanced Raman spectra of the two thiazole orange derivatives, TO6 {1‐(N,N'‐tetramethyl‐1,3‐propanediaminopropyl)‐4‐[3‐methyl‐2,3‐dihydro(benzo‐1,3‐thiazole)‐2‐methyliden] quinolinium triiodide} and TOTO {1,1′‐(4,4,8,8‐tetramethyl‐4,8‐diazaundecamethylene)‐bis‐ 4‐[3‐methyl‐2,3‐dihydro(benzo‐1,3‐thiazole)‐ 2‐methylidene] quinoliniumtetraiodide}, were recorded with visible (457.9 and 514.5 nm) and near‐infrared (1064 nm) excitation on silver colloids. The spectra were compared with the corresponding non‐enhanced Raman spectra obtained in the near‐infrared region and the resonance Raman spectra obtained with visible excitation. The qualitative enhancement pattern is explained within the electromagnetic theories. Partial assignment of the vibrational wavenumbers was achieved by comparison of observed band positions and intensities in the IR and Raman spectra with wavenumbers and intensities from quantum chemical calculations. Information on the adsorption geometry at the silver surface can be obtained on basis of this assignment. The surface‐enhanced Raman spectrum of TOTO on gold colloids was recorded with 1064 nm excitation and compared with the corresponding spectra on silver colloids.
Deconvolution of the Raman spectrum of amorphous carbon
Authors: Wang Qi , Allred D. D. , Knight L. V.
Published: May 2005

A constrained non‐linear deconvolution method was used to analyse the Raman spectrum of amorphous carbon. The method was tested by applying it to a model spectrum. Before the deconvolution the observed Raman spectrum was smoothed by a least‐squares convoluting procedure. The proper width of the spread function used in the deconvolution was determined by examining the reversibility of the deconvolution process. The deconvolution result for the Raman spectrum of amorphous carbon has a form very similar to the phonon density of states of graphite. This is taken to be additional evidence for Shuker and Gamon's model for Raman spectra of amorphous materials. Potentially, the deconvolution method can also be used for other aspects of Raman spectrum analysis of amorphous materials, such as finding the relative intensity of each peak of study the structure of the material.
The effect of cytoplasmic proteins on the reaggregation of dissociated ghost membranes of Bacillus megaterium KM
Authors: Devor K. A. , Makula R. A. , Lennarz W. J.
Published: May 2005

The effect of cytoplasmic proteins on the reassociation of membrame proteins and lipids which have been solubilized in sodium dodecyl sulfate and urea has been investigated. The cytoplasmic proteins have been found to inhibit the reassociation of the membrane proteins. Moreover, approximately 15% of the cytoplasmic proteins co‐aggregate with the membrane components after removal of the sodium dodecyl sulfate and urea.
Selective solubilization of proteins and phospholipids from red blood cell membranes by nonionic detergents
Authors: Yu John , Fischman Donald A. , Steck Theodore L.
Published: May 2005

Treatment of isolated human erythrocyte membranes with Triton X‐100 at ionic strength ⋍0.04 preferentially released all the glycerolipid and glycoprotein species. At low ionic strength, certain nonglycosylated polypeptides were also selectively solubilized. The liberated polypeptides were free of lipids, but some behaved as if associated into specific oligomeric complexes. Each detergent‐insoluble ghost residue appeared by electron microscopy to be a filamentous reticulum with adherent lipoid sheets and vesicles. The residues contained most of the membrane sphingolipids and the nonglycosylated proteins. The polypeptide elution profile obtained with nonionic detergents is therefore nearly reciprocal to that previously seen with a variety of agents which perturb proteins. These data afford further evidence that the externally‐oriented glycoproteins penetrate the membrane core where they are anchored hydrophobically, whereas the nonglycosylated polypeptides are, in general, bound by polar associations at the inner membrane surface. The filamentous meshwork of inner surface polypeptides may constitute a discrete, self‐associated continuum which provides rather than derives structural support from the membrance.
Purification and properties of the sodium–potassium transport adenosinetriphosphatase from the rectal gland of the spiny dogfish squalus acanthias
Authors: Hokin Lowell E.
Published: May 2005

The (Na + K)–activated adenosinetriphosphatase (NaK ATPase) has been purified from Lubrol extracts of membranes from the rectal glands of Squalus acanthias. The specific activity of the purified enzyme is 2 to 3 times that previously reported by others after correction of their specific activities for detergent activation. The yield of the enzyme from the membranes is 70%. The enzyme is highly stable both at 0° and in the frozen state. Ninety‐five percent of the enzyme consists of two subunits–the catalytic subunit with a MW of 97,000 and a glycoprotein with a MW of 55,000. At the last stage of purification the enzyme reverts to various membranous forms: the thickness of the membrane is about 80 Å; projections (probably the glycoprotein) of about 40 Å in diameter are seen at regular intervals.
The β‐glucoside system of Escherichia coli III. Properties of A P–HPr: β‐Glucoside phosphotransferase extracted from membranes with detergent
Authors: Rose Steven P. , Fox C. Fred
Published: May 2005

A P‐HPr:β‐glucoside phosphotransferase (enzyme IIbgl)

The nomenclautre of the enzymes II is that suggested by Lin (1)

has been extracted from membranes of a β‐glucoside fermenting strain of Escherichia coli K 12 using the nonionic detergent Triton X–100. The extracted enzyme was rendered virtually free of both lipid and detergent by chromatography on DEAE‐cellulose. At this stage, the partially purified enzyme had negligible activity, but activity was restored effectively by the addition of (1) nonionic detergents of the Tween or Triton series and (2) crude E. coli phospholipids or an anionic lipid enriched fraction, but not phosphatidylethanolamine. Detergent activators were most effective at or near the critical micelle concentration, but were inhibitory when added at concentrations above the critical micelle concentration.

In order to obtain maximal initial rates of phosphotransferase activity, it was necessary to incubate the extracted, partially purified enzyme with detergent activator and HPr prior to the addition of the other assay system components. High detergent concentration inhibited the initial rate of phosphorylation by interfering with an essential step (or steps) that occur during this preliminary incubation. The activation occuring during the preliminary incubation was also highly temperature dependent; a precipitous decrease in activation was detected below 16° when Tween 40 was employed as the detergent activator.

Phosphorylation mediated by the membrane associated form of the phosphotransferase was not influenced by the physical state of the lipid components of the membrane. This is in marked contrast to the properties of the phosphorylation reaction mediated by the phosphotransferase in intact cells.
Assembly and attachment of bacteriophage T4 tail fibers
Authors: Bishop R. J. , Conley M. P. , Wood W. B.
Published: May 2005

Bacteriophage T4 tail fibers are rodlike structures with a contour length of about 1400 Å, a diameter of about 45 Å, and a total mass of about 600,000 daltons. The assembly of the tail fibers and their subsequent attachment to the phage particle are under the control of 8 phage‐induced proteins. The gene control and molecular weight of each protein are known. The sequence of gene‐controlled steps has been determined by the characterization of intermediates that accumulate when various steps are blocked by mutation. The protein composition of the fibers and their precursors has been determined by purification and electrophoretic analysis.

Four of the eight gene products are structural components of the tail fiber. These proteins are P34 (150,000 daltons, 2 copies), P37 (120,000 daltons, 2 copies), P35 (40,000 daltons, 1 copy), and P36 (24,000 daltons, 2 copies). The wac (whisker antigen control) gene product is a structural component of the phage whiskers. The remaining three gene products, P38, P57, and P63, are not structural components of the phage particle. Both P63 and the wac gene product promote the attachment of tail fibers to the phage particle. P63 has been shown to act catalytically. Both P38 and P57 are somehow involved in the folding of the major tail fiber structural proteins (P37 and P34). The normal requirement for P38 and P57 functions can be bypassed by secondary mutations.
P22 morphogenesis II: Mechanism of DNA encapsulation
Authors: Tye Bik‐Kwoon , Botstein David
Published: May 2005

Phage P22 is known to have a linear duplex chromosome which is circularly permuted and terminally repeated. The propagation of these features of the mature phage DNA is accounted for by the fact that phage DNA lengths (headfuls) are cut from an intracellular intermediate form of phage DNA several phage genomes in length (concatemer) as first suggested by Streisinger. Studies with mutant phages show that cutting of concatemer DNA is intimately connected to the morphogenesis of the phage head.

We have also found, by constructing a partial denaturation map of mature P22 DNA, that circular permutation in P22 DNA is restricted: all of the ends of the mature DNA fall within 20% of each other on the physical map. The limited distribution of ends can be explained by Streisinger's “headful” packaging model with the additional specifications that: a. the intracellular precursor DNA is no longer than ten times the length of mature phage DNA; b. encapsulation of DNA starts at a unique site; c. encapsulation proceeds sequentially therefrom.

This model is supported by the distribution of molecular ends in denaturation maps of two deletion phage DNAs. We found, as expected from our model, that the extent of permutation is a direct function of the length of terminal repetition.
The role of ring aggregates and other structures in the assembly of microtubules
Authors: Weisenberg R. C.
Published: May 2005

Beef brain tubulin isolated by cycles of polymerization and depolymerization contains two components, 6S subunit and a 25–35S boundary containing ring‐shaped aggregates of tubulin. The rings disappear during microtubule polymerization, and the incorporation of ring tubulin into microtubules has been investigated by studying the changes in the sedimentation of tubulin which occur during polymerization. The “30S” boundary was separated from the 6S boundary by sedimentation at low temperatures. The temperature was then raised by letting a small amount of air into the vacuum chamber and the changes in sedimentation rate and concentration of each component determined as the tubulin polymerized. The 30S material polymerizes preferentially as determined by its decrease in concentration at polymerizing temperatures. Simultaneously with its decrease in concentration the 30S also decreases in sedimentation rate. The decrease in concentration of the 30S correlates well with polymerization while the decrease in sedimentation rate can occur independently of polymerization. The results indicate that the rings are not transformed directly into microtubules, but break down into subunits or small aggregates and these then assemble into microtubules. The rings may serve as a “storage aggregate” of active subunits. The presence of a possible storage aggregate in a dividing cell, the eggs of the surf clam, Spisula solidissima, has been indicated by measurements of particulate tubulin changes during the cell cycle. Microtubule assembly in vitro in homogenates of these eggs indicates that the amount of tubulin which forms microtubules may be controlled by the functioning of the microtubule organizing center.
Assembly of lipids and proteins in escherichia coli membranes
Authors: George‐Nascimento C. , Zehner Zendra E. , Wakil Salih J.
Published: May 2005

Presently there is much interest in the relationship between the structure and function of biological membranes. An approach to the understanding of this relationship has been the study of the effect of the modification of the membrane lipids on the function of membrane‐associated activities. In our laboratories we have modified the apolar portion of the membrane lipids of unsaturated fatty‐acid auxotrophs of Escherichia coli and investigated the effect of such modifications on enzymes of the electron‐transport system. From these studies we were able to conclude that E. coli regulates the relative fatty‐acid content of its phospholipids and maintains a certain membrane fluidity necessary for proper membrane function (1–3). We have also proposed that lipids are heterogeneously distributed within the membrane in domains of differing fluidity (4). The studies of McConnell, Chapman, and others (5–13) have corroborated these concepts and extended them to other biological and model membranes. In this paper we review some of our previous results and present evidence to show how NADH and D‐lactate oxidases of E. coli membranes are influenced by the fluid states of membrane phospholipids. Preliminary evidence is also presented to show that biogenesis of membranes probably occurs by independent insertion into the membranes of lipids and proteins which upon subsequent interaction with each other form the functional lipoprotein units.
On the molecular basis of action of cytochalasin B
Authors: Lin Shin , Spudich James A.
Published: May 2005

Tritium‐labeled cytochalasin B binds rapidly and reversibly to mammalian cells, and a class of high‐affinity sites (Kn ≅ 10−7 M) and a class of low‐affinity sites (KD ⩾ 10−5 M) are detected. In red blood cells, the high‐affinity binding sites (about 3 × 105 per cell) are associated with the plasma membrane, and at least 80% of these appear to be intimately related to the glucose transport system. Fractionation of cellular components of platelets by differential centrifugation and gel filtration chromatography reveals that the high‐affinity binding sites in these cells are also associated with membranous materials. A substantial number of the low‐affinity binding sites can be traced to platelet actin. The binding of cytochalasin B to actin is consistent with the alteration of intrinsic viscosity and morphology of actin filaments in vitro by the compound at concentrations of around 10−5‐10−4 M. The interaction of cytochalasin B with actin may account for its inhibitory effect on various forms of cell motility.
Light energy conversion in halobacterium halobium
Authors: Stoeckenius Walther , Lozier Richard H.
Published: May 2005

Halobacterium halobium carries out photophosphorylation. A rhodopsin‐like protein, bacteriorhodopsin, located in the cell membrane mediates the first step in energy transduction, the conversion of light energy into a chemiosmotic gradient. After absorption of a photon, bacteriorhodopsin undergoes a series of fast reactions, returning to its original state in a few milliseconds. In continuous light it cycles continuously at 100 to 200 cps. During a cycle protons are taken up on the cytoplasmic side of the membrane and released on the outer surface, thus generating a chemiosmotic gradient which can drive phosphorylation of ADP to ATP.
On the physiological functions of teichoic acids
Authors: Tomasz Alexander , Westphal Monika , Briles Eve B. , Fletcher Paul
Published: May 2005

The choline‐containing teichoic acids of pneumococci can be modified by biosynthetic replacement of the choline residues with certain structural analogues, such as ethanolamine (EA) or the N‐monomethyl‐ (MEA) and N‐dimethyl‐ (DEA) amino derivatives of ethanolamine. Cells containing such analogues in their teichoic acids develop pleiomorphic alterations in several physiological properties, which include resistance to detergent‐induced lysis and inhibition of cell separation (chain formation). We report here the results of physiological studies on the mechanism of these two phenomena. Our results are summarized in the following: (a) Pneumococci grown on various amino alcohols produce cell walls of identical amino sugar and amino acid composition. (b) Both choline‐ and EA‐containing teichoic acids seem to follow the same conservative pattern of segregation during growth and cell division. (c) Lysis sensitivity of pneumococci requires the juxtaposition of lysissensitive (choline‐containing) cell walls and endogenous autolysin at the cell wall growth zone. (d) Upon readdition of choline to ethanolamine‐containing cells, lysis sensitivity and catalytically active (C‐type) autolysin reappear in the bacteria with the same kinetics. (e) The chains of EA‐grown pneumococci contain fully compartmentalized cells and normal cross walls.