bluuebunny/crossref_metadata_2025 huggingface dataset:
Fourier transform Raman study of glass‐fibre‐reinforced poly(ethylene terephthalate)
Authors: Quintanilla L. , Rodríguez‐Cabello J. C. , Pastor J. M.
Published: May 2005

FT‐Raman spectroscopy has been proved as a useful tool to form the quantitative study of conformational changes in glass‐fibre‐reinforced annealed poly(ethylene terephthalate) (PET). Based on composite Raman bands directly related to the ethylene glycol fragment in the trans and gauche conformations, it was observed that glass‐fibre‐reinforced PET exhibits the same two‐phase conformational model as the isolated matrix. In contrast to the matrix, annealing thermal treatment of the composite does not seem to affect the composite microstructure since the isomer contents remain constant with annealing temperature. Thus, the microstructure is mainly determined by the fabrication process and its effect is similar to that observed in an annealed matrix at the highest temperatures. Therefore, the disordered trans isomer content can be considered negligible in the composite. In contrast to the spectroscopic results, the crystallinity values of the composite obtained by differential scanning calorimetry (DSC) only tend to coincide with those of the annealed matrix at temperatures above 150°C, and below this temperature they are always lower. A comparison between the results obtained by FT‐Raman and DSC techniques seems to indicate an improvement in the fibre–matrix interface in which an interfacial structure with a low degree of perfection changes to more perfect crystals.
Effects of vinyl substitutions on resonance Raman spectra of (bacterio)chlorophylls
Authors: Feiler Ute , Mattioli Tony A. , Katheder Ingrid , Scheer Hugo , Lutz Marc , Robert Bruno
Published: May 2005

Soret resonance and Qy preresonance Raman spectra are reported and compared for a series of (bacterio)chlorophylls. Chlorophyll a, 2‐acetylchlorophyll a, bacteriochlorophyll a and 2‐vinylbacteriochlorophyll a were studied in the non‐protic solvent tetrahydrofuran. These experiments were designed to identify Raman bands corresponding to the stretching mode(s) of the vinyl group at the C‐2 position of ring I of chlorophyll a and 2‐vinylbacteriochlorophyll a, and to ascertain whether additional bands corresponding to Ca Cm and/or Cb Cb vibrations could be observed in the 1615–1660 cm−1 region. Raman spectra of chlorophyll a and 2‐vinylbacteriochlorophyll a exhibit a 1625 cm−1 band, which is absent from the Raman spectra of 2‐acetylchlorophyll a and bacteriochlorophyll a. It is assigned to the vC2a C2b mode of the vinyl group. No other band can be definitively assigned to any mode predominantly arising from vinyl motions. The acetyl‐containing molecules 2‐acetylchlorophyll a and bacteriochlorophyll a give rise to a ca. 1070 cm−1 band, which appears to be related to the presence of the acetyl substituent. The 1615–1660 cm−1 region of the Raman spectra of all four derivatives did not contain any additional band which could be ascribed to modes involving the vCa Cm and/or νCb Cb coordinates.
Raman study of saturated ZnBr2(CdBr2)CH3CNH2O solutions in the CN stretching region
Authors: Astinov V. H. , Stoev M. D.
Published: May 2005

Raman spectroscopy was used to study the complexation in saturated ZnBr2(CdBr2)CH3CNH2O solutions at 25°C within the CN stretching region. Using the Fourier deconvolution procedure for spectral contours, the formation of the complex (CH3CN)Zn2+ in saturated and unsaturated (0.2 mole fraction CH3CN) solutions of the system ZnBr2CH3CNH2O was studied. The Fermi resonance interaction between 2253 and 2290 cm−1 determines opposite directions of the combination band shift for the two systems. The differences in complexation of Zn2+ and Cd2+ in the mixed solvent are discussed on the basis of the preferred cation solvation by the solvent molecules.
Surface‐enhanced Raman spectra of langmuir–blodgett monolayers of (hexadecamethyltetralino) porphyrazines
Authors: Souto J. , Aroca R. , Desaja J. A.
Published: May 2005

Langmuir monolayers of metal‐free tetra(1,1,4,4‐tetramethyl‐6,7‐tetralino) porphyrazine (HDMTLPH2) and its copper complex (HDMTLPCu) were formed on a water subphase. The surface pressure‐area isotherms were measured and the floating monolayers were transferred to various substrates. The spectra of Langmuir‐Blodgett (LB) films deposited on metal surfaces were studied. Surface‐enhanced Raman spectra of a single LB monolayer of HDMTLPH2 and HDMTLPCu deposited on rough surfaces (silver‐coated tin spheres and island films of silver and gold) are reported. Reflection absorption Fourier transform IR spectra of LB films on smooth silver are also presented. The spectroscopic characterization includes the UV‐visible spectra of multilayer films on glass slides, solutions and the bulk materials. Characteristic vibrational wavenumbers are listed and used to discuss molecular orientation in the LB assemblies.
Pre‐resonance Raman effect of solid‐state phenothiazine
Authors: de Faria D. L. A. , Santos P. S.
Published: May 2005

The band intensities of Raman spectrum of PTZ in the solid state show a clear dependence on the laser excitation wavelength. Such a behaviour, not observed when the spectrum is obtained from PTZ in solution, indicates that in the crystal the molecular. orbital of the compound is perturbed to some extent. The PTZ · SO2 complex in solution presents the same pre‐resonahce pattern as does solid PTZ, suggesting that the same PTZ orbital is involved in both cases. The most enhanced PTZ modes are those ascribed to the aromatic ring vibrations, indicating an interaction through the π molecular orbitals; it is proposed that PTZ acts as a π‐donor toward SO2 on the basis of the pre‐resonance pattern of the Raman spectrum of PTZ · SO2.
Electrodes for REMPI spectroscopy in static gases and calculation of REMPI intensities: Application to molecular oxygen
Authors: Rouillé G. , Chaux R. , Berger H. , Pavone F.
Published: May 2005

Resonance‐enhanced multiphoton ionization (REMPI) of 16O2X3∑g − (ν = 0) through (3sσg)d 1Πg, (ν = 0) by using (2 + 1) one‐colour photons is reported. This REMPI process, already observed and analysed by other authors at low pressure and low rotational temperature with mass spectrometry detection, is used to test our first detector of ionizations. Experimental difficulties have led to the design of an original arrangement of electrodes to collect electrons at room temperature and 1 Torr pressure of static molecular oxygen. A calculated spectrum is compared with the observed REMPI spectrum. The calculation uses the polarizability tensor and takes into account the competition between ionization and predissociation of the Rydberg state.
Light‐scattering spectrum in the region of the upper, lower and double critical points in guaiacol—glycerol solution
Authors: Chaikov L. L. , Fabelinskii I. L. , Krivokhizha S. V. , Lugovaya O. A. , Citrovsky A. , Jany P.
Published: May 2005

The viscosity temperature dependence and the correlation radius of concentration fluctuations have been obtained in guaiacol‐glycerol solutions with various miscibility gaps up to a gap width ΔT = 0.01 °C. The correlation radius critical exponent ν changes from 0.63 when ΔT= 39°C to 0.53 when ΔT = 0.01 °C. Measurements were made using the light correlation spectroscopy method.
Non‐linear processes in resonance Raman scattering
Authors: Sushchinskiy M. M.
Published: May 2005

A theoretical analysis is presented of resonance Raman scattering in disperse absorbing media, based on consideration of non‐linear four‐photon processes. A comparison of the theory with experiments is given.
Raman and infrared spectra of solid methylene fluoride
Authors: Beardsall A. J. , Smith W. , Anderson A.
Published: May 2005

Raman and infrared spectra of solid CH2F2 (Freon 32) were recorded in both the lattice and internal mode regions for samples at temperatures between 12 and 115 K. No evidence of any solid‐state phase transition or of metastable phases was found. The spectra are consistent with a large unit cell, probably non‐centrosymmetric and containing eight molecules, with relatively loose packing compared with the other methylene halides. It is postulated that at temperatures near the melting point, the molecules undergo 180° rotational jumps which are gradually inhibited on cooling.
Polarized single‐crystal Raman spectroscopy of danburite, CaB2Si2O8
Authors: Best Stephen P. , Clark Robin J. H. , Hayward Chris L. , Withnall Robert
Published: May 2005

Polarized single‐crystal Raman spectra were collected from the borosilicate feldspar mineral danburite (CaB2Si2O8) over the region 1800–40 cm−1. The symmetry of danburite (orthorhombic) is higher than that of the other feldspars (monoclinic or triclinic) and this simplifies the vibrational analysis. A very high proportion (74/78) of the bands due to Raman‐active fundamentals are observed, making this the first such study in which most of the bands for a feldspar mineral have been observed. Assignment of bands to stretching, bending and lattice modes is problematic because of the framework structure of the feldspar. The physically unrealistic disconnection of the danburite lattice into [Si2O7]6−, [B2O]4+ and Ca2+ ions leads to remarkably good predictions of the numbers of bands for each symmetry species in the wavenumber ranges appropriate for the Si(B)OSi(B) stretching (1300–825 cm−1), bending (825–390 cm−1) and lattice (390–90 cm−1) modes.
Meta‐substituted styrene molecules included in cydodextrins: A Raman spectroscopic study
Authors: Amado Ana M. , Moreira da Silva Aida M. , Ribeiro‐Claro P. J. A. , Teixeira‐Dias J. J. C.
Published: May 2005

Raman spectra of styrene (S), 3‐fluorostyrene (3FS), 3‐chlorostyrene (3CS) and 3‐methylstyrene (3MS) and their complexes in α‐, β‐ and γ‐cyclodextrins (α‐, β‐, γCD) were recorded at various temperatures. The substituted styrene molecules were found to provide good group frequencies, namely, vCC and vCH, for probing the guest molecules. Generally, the CC oscillator is shown to be a good probe for studying conformational equilibria of the guest molecule perturbed by complex formation with the various CD molecules. The CH oscillators provide information concerning plausible structures for the complexes. On the whole, all the spectral observations are consistent with different types of structures for the (S, 3MS)–αCD and (3FS, 3CS)–αCD complexes. In particular, the Raman spectroscopic results suggest that, for 3MS–αCD the vinyl group keeps some rotational freedom. For 3FS–αCD and 3CS–αCD, it is suggested that the most electronegative fluorine and chlorine atoms are left outside the the CD cavity, with the vinyl group rotationally hindered. For the γCD complexes, the wider CD cavity sould be able to accommodate all the guest molecules considered keeping the conformer distributions of the pure liquids approximately. However, the inclusion process seems to hinder the internal rotation in such a way that even below 200 K the conformer distribution remains similar to that of the pure liquid at room temperature.
Time‐resolved pump–probe Raman spectroscopy with temporally incoherent light
Authors: Okamoto Hiromi , Nakabayashi Takakazu , Tasumi Mitsuo
Published: May 2005

A method for picosecond time‐resolved pump–probe Raman spectroscopy using temporally incoherent light (‘incoherent pump–probe Raman spectroscopy, or simply IPPR spectroscopy’) is proposed. The theoretical formulation of IPPR scattering based on Gaussian random statistics is described. It is predicted that the temporal resolution in IPPR experiment is not determined by the duration of pump and probe pulses, but by the cross‐correlation time between the pump and probe lights. The delay‐time dependence of the IPPR intensity is expected to show the same behaviour as that in conventional time‐resolved Raman spectroscopy which uses coherent ultra‐short light pulses, except for a constant background always existing in IPPR scattering. This method was examined experimentally for Raman scattering from electronically excited trans‐stilbene in n‐hexane solution. In accordance with the prediction, picosecond decay of the Raman band at 1565 cm−1 arising from the trans‐stilbene molecules in the S1, state is observed with the use of nanosecond pump and probe pulses with a cross‐correlation time of ca. 100 ps. No decay is observed for the Raman bands of the solvent. Effects of saturation arising from the frequency‐doubling, pumping and Raman processes on the IPPR signal are also discussed. The ratio of the delaytime dependent part to the background (contrast ratio) is predicted to decrease in the presence of saturation.
Raman spectroscopic study of the molecular conformation of α‐octyl‐ω‐methoxyoligo(oxyethylene)s in the solid state
Authors: Masatoki Sei , Matsuura Hiroatsu , Fukuhara Koichi
Published: May 2005

The Raman spectra of α‐octyl‐ω‐methoxyoligo(oxyethylene)s, CH3(CH2)7(OCH2CH2)mOCH3 (m = 1–4), were measured in the solid state. The molecular conformation of these compounds was determined by a spectral analysis based on the key conformational bands. The conformation of the inner oxyethylene segments changes from an extended structure to a helical structure as the number of oxyethylene units increases. The difference in the conformational behaviour between the present methoxy‐ended compounds and the corresponding hydroxy‐ended compounds is associated with the different layer structures of the crystals.
Rovibrational Raman spectrum of dimethylacetylene
Authors: Meßler P. , Schrötter H. W. , Sarka K.
Published: May 2005

The rovibrational Raman spectrum of dimethylacetylene (but‐2‐yne) was recorded photoelectrically at medium resolution. Depolarization ratios and relative normalized scattering cross‐sections were determined for five fundamentals and a number of strong overtones.
Fourier transform Raman spectroscopy of bacterial cell walls
Authors: Williams A. C. , Edwards H. G. M.
Published: May 2005

Fourier transform Raman spectra were obtained from viable colonies of bacteria. Despite the highly coloured nature of the samples, the spectra were of sufficient quality to allow comprehensive assignments consistent with the vibrational modes. The spectra showed no clear evidence for the presence of phospholipids, indicating that penetration of the exciting infrared radiation was limited to the outermost components of the bacterial cell walls. The data describing the molecular and conformational state of the bacterial cell wall may aid in probing the modes of action of a wide range of antimicrobial agent.
Band profile analysis of the Raman spectra of sulphate ions in aqueous solutions
Authors: Rull F. , Sobrón F.
Published: May 2005

A Raman spectroscopic study of aqueous solutions of sulphates with some mono‐ and divalent cations was performed. The dynamic properties of the sulphate ion were analysed in the wavenumber domain and in the time domain using Fourier transform methods. Special interest is devoted to those systems for which the ν1(SO) band shows an asymmetric profile. This asymmetry has been interpreted in two ways: (a) as arising from different SO oscillators (associated and non‐associated); their relative intensity is calculated using classical fitting methods, although the band parameters are obtained from a self‐deconvolution method performed in the time domain; and (b) as arising from a perturbation of the water molecules in the vicinity of the sulphate ion. This perturbation is modelled in the time domain through a generalized correlation function. This latter represents a perturbed distribution of oscillators which undergo mutual interactions. These interactions are modelled by a feedback mechanism with two main parameters, the mutual coupling energy and the fraction of the distribution having mutual interaction. The correlation function thus modelled leads in the frequency domain to an asymmetric bandshape. The fitting of the experimental correlation function by this model gives essentially the same information as the fitting in the wavenumber domain for all the cases studied. Moreover, in the case of Li and Mg sulphates, both methods give the same value for the spectroscopically measured association enthalpy, 14 kJ mol−1 for Li and 21 kJ mol−1 for Mg.
Low‐wavenumber Raman spectrum of pyrazinic acid
Authors: Kalkar A. K. , Bhosekar N. M.
Published: May 2005

The low‐wavenumber Raman spectrum of pyrazinic acid (PA) crystal (orthorhombic, Pna21/D) was measured in the range 200–10 cm−1. Twelve Raman‐active lattice modes of crystalline PA were observed. Their tentative assignments in terms of hydrogen bond motion are reported. The intra‐ and inter‐chain translational modes were assigned using the isolated single‐chain (Cs) approximation, whereas the rotational modes were separated out mainly on the basis of their polarization behaviour, intensities and the shapes of their band profiles.
Isothermal Raman depolarization ratios of supracritical carbon monoxide at pressures between 20 and 2400 bar
Authors: Rose E. J. , Baglin F. G.
Published: May 2005

The Raman depolarization ratios of carbon monoxide were measured via the zeroth spectral moment, Mo (integrated intensities), and simple peak‐height determinations under isothermal conditions (323 K) over a pressure range of 20–2400 bar in a mixture of CH4 and CO. These conditions correspond to densities ranging from 0.75 to 24 mol I−1. The measurements were carried out so that the depolarization ratios being measured in other experiments from the ν1 totally symmetric stretching mode of supracritical methane could be corrected for instrumental depolarization effects. The values near a pressure of 1 bar have been calculated and measured for CO by several sets of workers. The cell windows were float glass and as a result they are known to contribute much less than quartz to depolarization. Float glass windows cause only a 0.5% error in scrambling uncertainty of the polarized light exiting the high‐pressure cell.
Surface‐enhanced Raman scattering at colloidal silver oxide surfaces
Authors: Li Ying‐Sing
Published: May 2005

A colloidal silver oxide hydrosol was prepared for surface‐enhanced Raman scattering (SERS). Its performance as a SERS‐active substrate was tested using benzoic acid and 1,1′‐diethyl‐2,2′cyanine iodide as analytes. SERS and surface enhanced resonance Raman scattering were observed for the adsorbed samples. In the preparation of the sol, the relative amounts of reagents should be an important factor in affecting the surface enhancement of the substrate. The surface enhancement activity of the colloidal hydrosol might indicate that silver oxide films generated in the electrochemical oxidation of a silver electrode could enhance the Raman spectra of adsorbed molecules and/or passivated films.
Resonance Raman enhancement for adenine and guanine residues
Authors: Majoube M. , Millié Ph. , Lagant P. , Vergoten G.
Published: May 2005

Reliable assignments for normal modes of adenine, 9‐methyladenine, guanine and 9‐methylguanine were obtained from ab initio 3–21G force fields and optimized geometries. In addition, relative itensities were calculated at resonance with the excited states corresponding to the lowest energy π–π * orbital excitations from the change in bond order and the L−1 matrix. Wavenumbers and relative intensities for resonance Raman active modes Were compared with those previously observed for resonance Raman enhanced bands of AMP and GMP in aqueous solutions obtained with excitation near the absorption band at 260 nm and below. There is satisfactory agreement between observed and calculated relative intensities for the guanine residue. In particular, the large increase in intensity observed for the CO stretching band at 1670 cm−1 with excitation below 220 nm is correctly reproduced. On the other hand, there is less agreement for the adenine residue where the distribution of intensity at resonance according to the A term of the resonance Raman theory is probably altered by the presence of vibronic coupling.
Raman and infrared study of neodymium oxide peroxide, Nd2O2(O2)
Authors: Heyns Anton M. , Range Klaus‐Jürgen
Published: May 2005

Nd2O2(O2) has been formed at very high oxygen pressures in an unsuccessful attempt to prepare neodymium(IV) dioxide, Nd4+ O2, and contains oxide (O2−) and peroxide (O) ions. The structure of Nd2O2(O2) closely resembles that of CaF2 and its full vibrational spectra could be interpreted in terms of this structure. Although Nd2O2(O2) has a monclinic structure, its vibrational spectra are not in agreement with the monoclinic B‐type phase of the lanthanide(III) sesquioxides, and it is shown why this is so. Many of the NdO vibrational modes in Nd2O2(O2) agree, however, with those observed in the trigonal A‐type Nd2O3, and the ν (OO) stretching and NdOO bending modes could be clearly identified.
SERRS of azurin adsorbed on a silver surface
Authors: Silin V. I. , Gaigalas A. K.
Published: May 2005

Surface‐enhanced resonance Raman (SERR) spectra of azurin, a copper‐containing protein, were measured on a silver surface with a double grating. Significant differences in intensity and band wavenumber were obtained between SERR and solution resonance Raman spectra in the region 250–300 cm−1 and near 400 cm−1. Preliminary interpretation of these differences suggests a likely orientation of the azurin protein on the silver surface in which the N(His44)N(His115)S(Met119) plane is perpendicular to the metal surface and the imidazole group of His115 is in close proximity to the metal.
Analytical potential of near‐infrared fourier transform Raman spectra in the detection of solid transition metal carbonyl steroid hormones
Authors: Salmain Michèle , Vessières Anne , Top Siden , Jaouen Gérard , Butler Ian S.
Published: May 2005

Near‐infrared (NIR) Fourier transform (FT) Raman spectra of four steroid hormones labeled with organometallic fragments, five steroid hormones and five model organometallic complexes were measured at room temperature. The objective was to determine which particular molecular vibrations of the steroid hormones might be best suited for any future quantitative analyses. On the basis of this FT‐Raman study, a classification of the most important vibrations as a function of their relative band intensities is proposed, i.e. v(Co2‐alkyne) ≈︁ v(Co‐Co) < v(C≡C) ≈︁ v(C‐C)Cp(Cp = β5‐C5H5) < v(C≡O) < v(C≡N).
Resonance Raman spectra of phthalocyanine monolayers on different supports. A normal mode analysis of zinc phthalocyanine by means of the MNDO method
Authors: Palys Barbara J. , van den Ham Dirk M. W. , Briels Wim , Feil Dirk
Published: May 2005

Resonance Raman spectra of monolayers of transition metal phthalocyanines reveal specific interaction with the support. To elucidate its mechanism, Raman spectra of zinc phthalocyanine monolayers were studied. The analysis was based largely on the results of MNDO calculations. Calculated wavenumbers turned out to be in good agreement with the experimental results. It seems plausible that the α‐nitrogen atoms dominate the interaction with the support. Calculation results also show that the usually assumed D4h geometry does not represent the true energy minimum but must be considered as the ‘mean’ of two mesomeric forms.
Application of fourier transform Raman spectroscopy to biomembranes: 1064 NM excited Raman spectra of hog kidney mitochondrial outer membranes
Authors: Omura Yoko , Muraishi Syuichi
Published: May 2005

Fourier transform Raman spectra with 1064 nm excitation were measured at ambient temperature on hog kidney mitochondrial outer membrane preparations of ultracentrifuged pellet and almost fluorescence‐free Raman spectra with satisfactory signal‐to‐noise ratios were obtained. Fourier transform IR spectra were also measured. The observed Raman and infrared wavenumbers were tentatively assigned to membrane proteins and phospholipids, respectively. CH stretching, phospholipid CC stretching and PO2− stretching vibrations are discussed. To examine the applicability of near‐infrared excited Fourier transform Raman spectroscopy to the study of the inhibitory effects of inorganic ions on membrane‐bound monoamine oxidase activity, measurements were also made on membrane preparations suspended in phosphate buffer (pH 7.0) at ambient temperature in the absence (control) and presence of NaCl, and studies were made of phospholipid CC stretching and PO2− stretching vibrations, which are relatively unaffected by H2O self‐absorption by near‐infrared radiation. It was found that the presence of NaCl decreased the intensity of the 1080 cm− 1 gauche form acyl chain CC stretching Raman band relative to those of the all‐trans CC stretching Raman band at 1126 and 1068 cm− 1. This result was different from that obtained with aqueous dispersions of phosphatidylcholine (PC), for which it has been reported previously that monovalent ions such as Na+ do not affect the Itrans/Igauche ratio.
Transient resonance coherent stokes Raman scattering spectra of photoinduced radical ions of diphenyloctatetraene in polar solvents
Authors: Kamisuki Toshio , Hirose Chiaki
Published: May 2005

Transient resonance coherent Stokes Raman scattering (CSRS) spectra of the photoinduced radical ions of all‐trans‐1, 8‐diphenylocta‐1, 3, 5, 7‐tetraene (DPO) were observed in polar solvents such as acetonitrile, N, N‐dimethylformamide and dimethyl sulphoxide. The identification was based on the long lifetimes and the dependence of their formation on the electron‐donating and/or ‐accepting nature of the solvents. The fluorescence spectra of DPO were also observed in the presence of N, N‐dimethylaniline (DMA) and p‐dicyanobenzene (DCNB) in p‐dioxane and in polar solvents without DCNB and DMA. The absence of an indication of exciplex formation, in contrast to the cases of diphenylbutadiene and diphenylhexatriene, can be related to the extremely low efficiency of the radical ion formation by solvent‐assisted photoionization in DPO—DMA and DPO—DCNB in p‐dioxane systems. The strong dependence of the CSRS signal of the DPO radical ions on the content of polar solvent in the high‐concentration region of the binary solvent systems with p‐dioxane suggests a collective behaviour of the polar solvents surrounding an S1 solute for the CT interaction to generate the radical ions. The observed Raman wavenumbers were compared with those of DPO in the S0, S1 and T1 states and qualitative correlation among them is discussed.
Vibrational analysis of poly(L‐lactic acid)
Authors: Kister G. , Cassanas G. , Vert M. , Pauvert B. , Térol A.
Published: May 2005

The Raman and IR spectra of poly(L‐lactic acid) in the amorphous and semicrystalline states were recorded from 3600 to 100 cm−1. Complete vibrational assignments are proposed. In the Raman spectra, the splittings of the vC=O stretching and the δCCO bend are characteristic of the crystalline phase and the presence of the two lines at 923 and 520 cm−1 indicates a 103 helical conformation.
Windowless cell for fourier transform Raman spectra of liquids and aqueous solutions
Authors: Brooker Murray H. , Nielsen Ole Faurskov , Christensen Daniel
Published: May 2005

Fourier transform (FT) Raman spectra were obtained for water and aqueous solutions in a stainless‐steel, windowless, liquid captive cell of simple design. It was demonstrated that high‐quality Raman spectra in the low‐wavenumber region (down to 100 cm−1) can be obtained from highly colored samples without the presence of interfering bands from the usual sample containers made of glass or plastic. Raman bands at 520 and 232 cm−1 due to the symmetric stretching modes of the Cr‐O vibration of the Cr(H2O) and the Cr‐Cl vibration of the CrCl complexes were observed for very dark samples that are not amenable to conventional Raman techniques. FT‐Raman studies of aqueous Cr(III) solutions can provide valuable information on the slow ligand exchange rates.
X‐ray structure determination and vibrational study of di(diaminophosphoryl)imide
Authors: Hammade Vasilica , Gnado Joseph , Dhamelincourt Paul , Conflant Pierre , Vignacourt Jean Pierre
Published: May 2005

Di(diaminophosphoryl)imide (PNH), NH[P(O)(NH2)2]2, has very interesting fireproof properties when linked to cellulosic material. The PNH structure, hitherto unknown, was first established by x‐ray diffraction and was found to be monoclinic (P21/c, a=5.206, b=8.311, c=14.889 Å, β = 92.86°, Z=4). Based on this structure, a normal coordinate analysis was undertaken which has permitted the assignment of most of the observed IR and Raman bands in the spectral range above 1000 cm−1. More particularly, the calculated NH2 stretching wavenumbers are consistent with the different hydrogen bond strengths indicated by x‐ray diffraction measurements. In the spectral range below 1000 cm−1, strong couplings between the NH and the PNH modes prevented a rigorous assignment of the observed bands.
Surface‐enhanced resonance Raman scattering study of the groove binding dye hoechst 33258
Authors: Zimmermann F. , Zimmermann B. , Panitz J.‐C. , Wokaun A.
Published: May 2005

The groove binding dye Hoechst 33258 was investigated both in aqueous solution and in the adsorbed form on silver colloids and island films. Fourier transform Raman, resonance Raman and surface enhanced resonance Raman spectra were used together with the results of a normal coordinate analysis for a comprehensive assignment of the rich vibrational spectrum. Relative band intensities in the SERRS spectra indicate that the molecule is adsorbed with its long axis oriented along the silver surface and with the planes of the benzimidazole rings approximately parallel to the surface. The molecule is bound to the surface as a cation protonated at a piperazine nitrogen atom and is desorbed on complete deprotonation.
Near‐infrared fourier transform Raman spectroscopy of indigoids
Authors: Tatsch Ellen , Schrader Bernhard
Published: May 2005

Near‐infrared Fourier transform Raman spectra (3400 to — 20 cm−1) for the solid phases of indigo, thioindigo, selenoindigo and N,N'‐dimethylindigo were recorded with excitation using Nd:YAG laser radiation at 1064 nm. A complete vibrational assignment is proposed supported by the results of ab initio calculations. The spectra are complementary to the IR spectra recorded earlier. They also complete earlier results of resonance Raman spectroscopy. The spectra support a molecular structure of the indigo chromophore with a cross‐conjugated vinylogue amide system.
Raman and infrared spectra, conformational stability, barriers to internal rotation and ab initio calculations of trifluoroacetyl isothiocyanate
Authors: Durig J. R. , Guirgis Gamil A. , Krutules K. A.
Published: May 2005

The Raman (3100‐10 cm−1) and infrared (3100‐30 cm−1) spectra of trifluoroacetyl isothiocyanate [CF3C(O)NCS] were recorded for the gas and solid. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. The observed bands are assigned on the basis of the more stable cis conformer (isothiocyanate group cis to the carbonyl bond) and the less stable trans conformer in the vapor state. From the variable‐temperature studies of the infrared spectrum of the sample dissolved in liquified xenon, two conformer pairs were used to determine a ΔH value of 104 ± 9 cm−1 (270 ± 26 cal mol−1). From the temperature dependence of the Raman spectrum of the liquid, two conformer pairs were used to determine experimentally a ΔH value of 90 ± 31 cm−1 (258 ± 88 cal mol−1), but for this physical state the trans conformer is the more stable form. In the annealed crystalline solid, only the trans conformer remains. A complete vibrational assignment is proposed for both conformers based on infrared band contours, Raman depolarization data, group wavenumbers and normal coordinate calculations. The experimental conformational stability, barriers to internal rotation and fundamental vibrational wavenumbers are compared with those obtained from the ab initio calculations employing the RHF/6‐31G* basis set and to the corresponding quantities obtained for some similar molecules.
Femtosecond time‐resolved vibrational spectroscopy of heme proteins
Authors: Zhu Leyun , Wang Wei , Sage J. Timothy , Champion Paul M.
Published: May 2005

Ultra‐fast pulsed laser measurements in the time domain have several advantages over traditional frequency‐domain spectroscopy. For example, very low frequency modes are more easily probed, fluorescent samples can be studied and vibrational modes that are directly coupled to chemical reactions are revealed. This study demonstrated some of these advantages using heme protein samples. Low‐frequency modes are observed in deoxymyoglobin (deoxyMb), fluorescence rejection is demonstrated with metMb and product‐state vibrational coherence is revealed with MbNO.
Anisotropy as an ultrafast probe of electronic coherence in degenerate systems exhibiting Raman scattering, fluorescence, transient absorption and chemical reactions
Authors: Wynne Klaas , Hochstrasser R. M.
Published: May 2005

The effects of electronic coherence of doubly or triply degenerate levels are discussed. This coherence will show up in the anisotropy of a pump—probe experiment in which a pump pulse creates the coherence and a probe pulse connects the degenerate levels to a non‐degenerate final state. Simple stochastic models for the decay of the anisotropy as a function of pump—probe delay are given, both for molecules with a high symmetry and for symmetric dimers and trimers. The possible role that degenerate level coherence may play in chemical reactions is also discussed. Finally, the stochastic models used to calculate the anisotropy decay are applied towards the calculation of absorption line shapes, Raman scattering and fluorescence.
Fourier transform Raman spectroscopic study of hydrogen bonding in 2,5‐dimercapto‐1,3,4‐thiadiazole using an environmental chamber
Authors: Lawson E. E. , Edwards H. G. M. , Johnson A. F.
Published: May 2005

The bands at 2485 and 940 cm−1 observed in the Raman spectra of 2,5‐dimercapto‐1,3,4‐thiadiazole represent the hydrogen‐bonded ν(SH) stretching and δ(C‐SH) in‐plane bending modes, respectively. A quantitative study of the hydrogen bonding was carried out using intensity measurements of the bands assigned to the hydrogen‐bonded and the free δ(C‐SH) in‐plane deformations at 940 and 919 cm−1, respectively, as a function of temperature. The Fourier transform (FT) Raman spectra were recorded over the temperature range 303‐403 K using an environmental chamber fitted into the FT Raman sample compartment. The equilibrium constants between the free and the hydrogen‐bonded molecules were determined over this temperature range and the average enthalpy for hydrogen‐bond formation was obtained (ΔH° = −3.35 ± 0.2 kJ mol−1).
Vibrational characterization of Langmuir—Blodgett films of octa‐(15‐crown‐5)‐lutetium bisphthalocyanine
Authors: Rodríguez‐Méndez M. L. , Souto J. , De Saja J. A.
Published: May 2005

Surface‐enhanced resonant Raman scattering and Fourier transform surface‐enhanced Raman scattering of Langmuir‐Blodgett monolayers of the green and blue forms of octa‐(15‐crown‐5)‐lutetium bisphtalocyanine prepared on gold island films are reported. The spectroscopic characterization was completed by measuring the Raman and Fourier transform infrared spectra of dispersions of the materials in KBr matrices. An empirical vibrational assignment of the observed fundamentals is given.
Fourier transform Raman spectroscopic study of lithium perchlorate solutions in acrylonitrile
Authors: Alia J. M. , Edwards H. G. M. , Moore J.
Published: May 2005

Lithium perchlorate solutions in acrylonitrile (propenenitrile), in a range of concentration between 1 and 6 molal, were studied by using Fourier transform Raman spectroscopy. The new band in the v(CN) region proceeding from the bound species Li+… (acrylonitrile)n and the modifications in the C—C stretching band were studied in detail by means of deconvolution and band‐fitting procedures. An average solvation number of ca. 2.3 was obtained without any correction for the ion pairing. The data obtained in the analysis of the perchlorate anion v1 (symmetric stretch) band allow us to quantify the concentration of the different species (free perchlorate, solvent‐separated ion pairs and contact ion pairs) present, and to obtain a more realistic solvation number for the lithium ion in acrylonitrile solutions. This solvation number was estimated at 3.0 ± 0.1.
Remote Raman spectroscopic studies of corrosion products formed on nuclear fuel claddings used in PWR and AGR systems
Authors: Edwards H. G. M. , Long D. A. , Willis I. T.
Published: May 2005

The construction of a remote Raman microscope system with a variable microscope‐to‐spectrometer distance of up to 3 m is described. Oxidative surface corrosion products on zirconium alloy and stainless‐steel nuclear fuel claddings for pressurized water and advanced gas cooled reactor systems produced under various conditions were studied and the potential of the technique for in situ analysis is discussed. Under the conditions studied experimentally, the major corrosion products are found to be α‐ZrO2 and α‐Fe2O3 for the zirconium alloy and stainless‐steel claddings, respectively.
Surface enhanced resonance Raman scattering from cyanocobalamin and 5′‐deoxyadenosylcobalamin
Authors: Quaroni L. , Reglinski J. , Smith W. E.
Published: May 2005

Surface enhanced resonance Raman scattering (SERRS) from cobalamins is reported. To achieve efficient adsorption and strong SERRS, the molecule is adsorbed on a polysine‐treated silver colloid surface. This provides an organic barrier between the cobalamin and the metal, preventing denaturation, and gives positively charged groups for efficient adsorption. The technique can be used for in situ studies of changes in the metal coordination sphere, as is illustrated by reduction on the surface using dithionite for both cyanocobalamin and 5′‐deoxyadenosylcobalamin. The efficient energy transfer at the surface appears to prevent photodegradation, which is a problem with resonance, and the efficiency of SERRS allows measurements at low effective concentrations.
Cell surface glycoproteins I: Accumulation of a glycoprotein on the outer surface of mouse LS cells during mitosis
Authors: Brown J. C.
Published: May 2005

Surface glycopeptides derived from vertebrate cells have been separated into 4 classes by chromatography on DEAE cellulose columns. Among different cell types tested, significant differences were observed in the relative amounts of these 4 glycopeptide classes present on the cell surface. This type of heterogeneity is consistent with the expected biological role of cell surface glycoproteins. One glycopeptide, as revealed by the DEAE column analysis, was found to have a characteristic metabolic pattern in mouse LS cells. New accumulation of this structure, called glycopeptide 4, on the cell surface was detected only around the period of cell division (M phase) and not at other times during the cell cycle.
Regulation of polar cap formation in the life cycle of Escherichia coli
Authors: Hoffmann Björn , Messer Walter , Schwarz Uli
Published: May 2005

Polar cap formation has been studied in synchronized Escherichia coli cells. It is dependent on a signal given after completion of a round of DNA replication. A 20 min time interval between the release of this signal and physical cell separation is probably the time required for the completion of polar caps. During this time murein is synthesized at an increased rate and cells are especially sensitive to penicillin.
Composition, structure and phase transition in yeast fatty acid auxotroph membranes: Spin labels and freeze‐fracture
Authors: James Robert , Branton Daniel , Wisnieski Bernadine , Keith Alec
Published: May 2005

Fatty acid desaturase mutant yeast cells have been enriched with 2 fatty acids having substantially different physical properties.

Differences in fatty acid composition are reflected in the ESR determined phase transitions and the freeze‐fracture morphology of the tonoplast.

In these cells, fatty acid composition, rather than the position of the phase transition relative to growth temperature, appears to be the more important variable in determining membrane morphology.

The freezing process used in the freeze‐fracture technique does not appear to cause a demixing of the lipid components of the membrane.
Study of envelope proteins in E. coli cet and recA mutants by SDS acrylamide gel electrophoresis
Authors: Holland I. B. , Tuckett Susan
Published: May 2005

Disc‐electrophoresis of E. coli envelope proteins on SDS acrylamide gels reproducibly revealed up to 50 distinct polypeptide bands. Corresponding molecular weights ranged from 105,000 to 20,000 daltons or less. Major bands corresponded to molecular weights of 73,000, 48,000, 36,000 and 30,000 with the latter constituting up to 20% of the total envelope protein depending upon the method of isolation. Minimum levels of detection using stained gels equaled 0.25 μg protein or 1% of total sample analyzed; for a polypeptide of molecular weight 40,000 daltons this was calculated to be equivalent to 1,200 molecules per cell envelope. In envelopes from a cetB− mutant strain (refractory to colicin E2), an additional band, constituting up to 5% of the total envelope protein was present. The molecular weight of this protein, which was maximally present in wild type envelopes in only trace amounts, is 44,000 daltons, indicating a cellular concentration of approximately 6 × 103 molecules per envelope. This new band was not affected by heating envelope preparations to 100° prior to electrophoresis, but was largely eliminated by washing isolated envelopes in low ionic strength buffer, or by pre‐incubating cells with trypsin prior to preparation of envelopes. Treatment of isolated envelopes with Triton X‐100, which preferentially releases inner membrane proteins from the envelope (18), resulted in the extraction of a preponderance of the high molecular weight polypeptides, including the 44,000 dalton protein from envelopes of the mutant. The major polypeptides of the envelope and the low molecular weight components were not extracted by Triton X‐100. The properties of the 44,000 dalton protein indicated that it is relatively loosely associated with the surface envelope and may be exposed on the external surface of the cytoplasmic membrane. Possible explanations for the appearance of this protein in mutant strains and its relationship to the inability of these to respond, specifically to surface bound colicin E2, will be discussed. Extensive analysis of envelopes from recA− mutants was also carried out and revealed an unusual amount of variation in polypeptide profiles obtained from different preparations. However, no consistent quantitative or qualitative difference between recA and rec+ strains was obtained. In recA, cetB double mutants, the increased level of the 44,000 dalton polypeptide was identical to that found in the rec+, cetB mutant.
Fluorescence and circular dichroism studies on human serum low density lipoprotein particles and lipid‐depleted derivatives
Authors: Pollard Harvey B. , Chen Raymond F.
Published: May 2005

The low density liporpotein from human serum, and derivitives prepared free of neutral lipids and total lipids, have been studied by fluorescence and circular dichorism methods. Removal of the neutral lipids had little effect on the tryptophan fluorescence at neutral pH. However, by the criteria of circular dichroism, over the range of 200 nm to 250 nm, there was a reduction in secondary structure of over 75%. Removal of the remaining phospholipids resulted in a qualitatively different structure by both fluorescence and circular dichroism criteria.

Neutral lipids were removed from LDL in a step‐wise fashion in order to determine the exact amount of neutral lipid required for the native circular dichroism spectrum. The circular dichroism band intensity was constant until approximately 10% of the total cholesterol (as cholesterol ester) remained. The intensity then abruptly dropped as more cholesterol was removed.

We concluded that the two spectroscopic methods report on two distinct aspects of LDL structure. The tryptophan fluorescence appears to be sensitive to the presence of phospholipids. The circular dichroism, however, appears to be sensitive to the binding of a small amount of neutral lipid. These findings suggest that a functional and geometric separation of binding sites may exist for these two classes of lipids. Such a distinction is predicted by the icosohedral model of the quaternary structure of LDL. In this model, the phospholipids are located on the surface of the particle, in the holes of an icosohedrally symmetric surface network of protein subunits; the neutral lipids are located in the particle core.

Finally, we suggest that functional significance may be attached to our finding that relatively few cholesterol ester molecles are needed to maintain the native secondary structure of LDL. This provides a mechanism whereby the amount of bound neutral lipid could be raised or lowered (for transport and transfer to cells) without affecting the protein in any structurally significant manner.
Protein composition of cell and forespore membranes of Bacillus subtilis
Authors: Goldman Robert C.
Published: May 2005

A sporulation mutant of Bacillus subtilis 168 was isolated and characterized. The mutant, designated SB‐23, releases viable forespores at the end of the developmental period. Forespores were isolated on linear Renografin gradients and used as a source of forespore membranes. The protein composition of forespore membranes was found to differ from the protein composition of vegetative cell membranes by discgel electrophoresis. The results are discussed in relationship to morphological and physiological differentiation during bacterial sporulation.
Isolation and characterization of a protease inhibitor from commercial stem bromelain acetone powder
Authors: Perlstein Seymour H. , Kéazdy Ferenc J.
Published: May 2005

Seven closely related protease inhibitors were isolated from commercial bromelain acetone powder in electrophoretically pure form by gel filtration on Sephadex G‐75, followed by ion exchange chromatography on DEAE Sephadex at pH 7.55. The inhibitors are proteins of MW 5000‐6000, which inhibit competitively the bromelaincatalyzed hydrolysis of CLN (Ki ≈ 10−7 M). This inhibition is optimal at pH 3 to 4,. and it depends upon the ionization of two acidic residues of pK = 4.5 and 5.0. In the acidic pH range the inhibitors are also effective toward papain, ficin and trypsin.
Conformational aspects of rhodopsin and retinal disc membranes
Authors: Steinemann Adrian , Wu Cheng‐Wen , Stryer Lubert
Published: May 2005

We have used two experimental approaches – fluorescence spectroscopy and lectin binding – to obtain information about the structure of rhodopsin and its position in retinal disc membranes. Energy transfer was used as a spectroscopic ruler to deduce proximity relationships in rhodopsin and in disc membranes. Concanavalin A and wheat germ agglutinin served as specific macromolecular probes of the accessibility of the carbohydrate unit of rhodopsin in disc membranes. We infer from these studies that: (1) The rhodopsin molecule is at least 75 Å long and has an elongated shape. (2) There may be distinct hydrophobic and hydrophobic and hydrophilic domains in rhodopsin. (3) The carbohydrate moiety of rhodopsin is on the surface of the disc membrane, probably only on the external face. (4) The disc membrane has an asymmetric structure. (5) The external surface of the disc membrane is closer to site A (a sulfhydryl residue on rhodopsin) than to 11–cis retinal.