摘要:

AbstractThe Raman spectrum of the amorphous material Te40As35Si18Ge7has been studied for the first time. It has been observed that the vibrational modes corresponding to the elemental amorphous material are present together with the modes belonging to the SiGe alloy system. The results suggest that this amorphous material demonstrates similarities to organic molecules where the presence and ordering of the neighbouring atoms have little effect on the eigenvalue of the vibrational mode of a particular grou

ISSN:0377-0486    

DOI:10.1002/jrs.1250150102

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractFormulae for the absolute differential Raman scattering cross‐sections of fundamental modes of gases, liquids and solids as a function of the invariants of the Raman tensors are reviewed. Explicit expresslons for the Raman tensors of planar and pyramidal MX3molecules are reported in terms of bond polarizability parameters. For the pyramidal MX3Molecules the coefficients of these expressions cannot be summarized easily in simple formulae since they depend on the atomic masses and on the tribedral angle of the pyramid, but numerical values are tabulated for 27 molecules and ions. Several approximations of the bond polarizability model are briefly reviewed in connection with the expressions for the Raman tensor

ISSN:0377-0486    

DOI:10.1002/jrs.1250150103

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractWe report the observation of the Raman modes of Br2molecules bound to graphite, KBr and fused quartz substrates. The results demonstrate that Br2bonds to surfaces at preferred sites, except in the case of fused quartz, where no unique site can be defined owing to its amorphous nature. The spectra of Br2on the KBr substrate, taken at later times, exhibit modes that are related to a chemical modification of the KBr substrate.

ISSN:0377-0486    

DOI:10.1002/jrs.1250150104

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractRaman spectra of highly oriented pyrolytic graphite electrodes with the basal plane exposed (BPG) and the basal plane edges exposed (EPG) have been investigated in aqueous acidic media using a rotating electrode cell. Anodic oxidation of these electrodes and subsequent reduction resulted in the original sharp band at 1581 cm−1being replaced by a broader band atca1600 cm−1with a new broad band associated with disordered carbon emerging in the 1300–1400 cm−1region. The Raman spectrum of multilayers of thionine (3,7‐ diaminophenothiazinium chloride) electrodeposited on BPG electrodes has been recorded. The spectral sensitivity has been found to be such that monolayer detection is unlikely at this

ISSN:0377-0486    

DOI:10.1002/jrs.1250150105

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe line shape observed in coherent Raman scattering (CRS) with excitation under conditions of electronic resonance is discussed, For the case of A‐type scattering, the complex Raman amplitude is related directly to the molecular one‐photon absorbance of the resonance transition concerned. The basis for this relation is transform theory, a method known from spontaneous resonance Raman scattering to relate the Raman excitation profile to the observed molecular absorbance. Features of the Raman amplitude, determining the observed line shapes for coherent anti‐Stokes Raman scattering (CARS) and for coherent Stokes Raman scattering (CSRS), are discussed qualitatively. The discussion considers two typical forms in which broad molecular absorption spectra of polyatomic molecules in the condensed phases appear, Inhomogeneous broadening leads to characteristic changes of the Raman amplitude in relation to molecular absorbance in the case of CSRS (formolecules in the electronic ground state), whereas for CARS the relation derived in the homogeneous broadened case remains valid. The special advantages of the CRS technique for determining the complex non‐Raman resonant (background) susceptibility from concentration dependence are demon

ISSN:0377-0486    

DOI:10.1002/jrs.1250150106

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe Raman spectra of aqueous solutions of calf thymus histone complexes H2A:H2B and H3:H4 have been recorded and are compared with those of the individual histones. The results show an increase of α‐helix content on formation of these complexes, at the expense of random‐coil conformation in H2A:H2B and β‐sheet structure in H3:H4. The α‐helix content is estimated to be 40% in H2A:H2B and 35% in the H3:H4 complex. The intensity ratios of the 850/830 cm−1components of the tyrosine doublet in the spectra of both complexes are the averages of the values for the individual histones, suggesting that the environment of these residues is little modified on formation of the complexes. Variations in the intensity of the 1400 cm−1carboxyl band has been observed to be associated with conformational changes, which is consistent with the notion that COO−/NH 3+, NH 2+interactions play a major role in histone

ISSN:0377-0486    

DOI:10.1002/jrs.1250150107

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThin solid films of Mg, Cu and Zn phthalocyanine complexes have been studied using Raman spectroscopy. Laser excitation lines near resonance and in resonance with the electronic absorption band of the substrate have been used. A description of vibrational modes is given and correlations in vibrational properties of the series are discussed.

ISSN:0377-0486    

DOI:10.1002/jrs.1250150108

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractAccurate theoretical expressions for Herman‐Wallis factors for the pure rotational, fundamental and first two overtone vibration‐rotational bands have been derived. These are expressed for arbitrary rotational quantum numbers in terms of the Dunham potential parameters and the coefficients of a general operator represented by a power series expansion. The inclusion of higher order corrections in a consistent way reduces the discrepancy reported by previous workers for H2between results obatined numerically and analytically. The present expressions are of sufficient accuracy to enable one to obtain precise experimental values for the anisotropy of the polarizability and its derivatives from an analysis of Raman line intensit

ISSN:0377-0486    

DOI:10.1002/jrs.1250150109

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe Raman spectra of the high‐temperature (α) phase of crystalline malonic acid, CH2(COOH)2, and its deuteriated derivative, CD2(COOD)2, have been investigated at 370 K in the wavenumber shift range 0–4000 cm−1. An assignment of the internal and external vibrations is given. Comparison of the infrared and Raman spectra of the α and β phases shows that the high‐temperature phase (α) consists of quivalent centrosymmetric dimer rings and that the corresponding space group isC 2h6C2/cwith molecules occupygingC2sites. The temperature dependence of various Raman lines, in particular those due to lattice modes, indicates that the phase transition is of first order and that during the transition, reorientation of the molecules about thecaxis is strongly coupled with the low‐frequency torsional (γOH…O) a

ISSN:0377-0486    

DOI:10.1002/jrs.1250150110

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe molecular theory of the scattering of polarized light is applied to the problem of the artefacts that frequently arise in Raman circular intensity difference measurements. By including the effect of the finite solid angle in the cone of collected light, a detailed understanding of the major sources of artefacts in polarized and depolarized measurements, and their dependence on the polarization characteristics of the Raman band, is obtained. Inclusion of both antisymmetric and symmetric scattering contributions reveals whymagneticare usually less susceptible to artefacts thannaturalRaman optical activity spectra.

ISSN:0377-0486    

DOI:10.1002/jrs.1250150111

出版商:John Wiley&Sons, Ltd.    

年代:1984

数据来源: WILEY