ISSN:0377-0486    

DOI:10.1002/jrs.1250210102

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe resonance Raman spectra of the lithium complexes of the 2,2′‐bipyridine anion radical and five isotopically labeled analogues, including the15N‐labeled species, are reported. All of the fundamental modes of vibration, excluding the CH stretching and several low‐frequency modes, have been identified. Care must be taken to avoid contamination of the sample with the dianion Li2bpy. In order to eliminate possible misassignment of bands to traces of Li2bpy, the spectra of the latter species were also investigated. The assignments of the vibrational frequencies to the fundamental modes of Libpy are supported by a normal coordinate calculation and the structural implications of the vibrational frequency shifts, relative to the neutral parent, are

ISSN:0377-0486    

DOI:10.1002/jrs.1250210103

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractFourier transform Raman and infrared spectra have been recorded of diazepam (7‐chloro‐1,3‐dihydro‐1‐methyl‐5‐phenyl‐2H‐1,4‐benzodiazepin‐2‐one) and four compounds with closely related structures. These compounds are all 7‐chloro‐1,3‐dihydro‐5‐phenyl‐2H‐1,4‐benzodiazepin‐2‐ones and differ only in the nature of the substituent (R) at N‐1. The five compounds are nordazepam (R  H), diazepam (R  CH3), pinazepam (R  CH2CCH), halazepam (R  CH2CF3) and prazepam (R  cyclopropylmethyl). Prominent features of the infrared and Raman spectra have been assigned to functional groups of the parent structure and the substituent groups. The spectra of nordazepam suggest that the compound exists as a centrosymmetric cyclic dimer in the solid state. Complete tabulations of the observed wavenumbers of the five molecules are given. The

ISSN:0377-0486    

DOI:10.1002/jrs.1250210104

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractResonance Raman spectra with excitations in the Soret region are reported for desulfoviridin, the sulfite reductase fromDesulfovibrio gigas.Desulfoviridin contains sirohydrochlorin, a hydroporphyrin of the type isobacteriochlorin. The typical spectrum shows a large number of bands, with the prominentv4* mode at 1336 cm−1. Using perturbation and group theories, we were able to develop some conceptual understanding of the in‐plane vibration modes of isobacteriochlorin. This has enabled us to arrive at the tentative conclusion that the sirohydrochlorin prosthetic groups in desulfoviridin are not coupled to any metal ion

ISSN:0377-0486    

DOI:10.1002/jrs.1250210105

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractRaman and infrared spectra of a series of double chromates of the type Lnk(CrO4)2, with Ln = La, Pr, Nd, Sm, were recorded and discussed with the aid of a factor group analysis. These substances constitute the first example showing the intercalation ofv1betweenv3components in crystalline chromates. The spectroscopic results confirm again the structural differences between these chromates and PbCrO4(synthetic crocoite), which was also investigated for comparison.

ISSN:0377-0486    

DOI:10.1002/jrs.1250210106

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe Raman spectra of 4‐(dimethylamino)benzaldehyde in the 1550–1750 cm−1region in seventeen solvents and as a molten liquid were measured. In all cases a multicomponent band was observed in the CO stretching region and these components were analyzed by the solvent variation method for Fermi resonance interactions. Unperturbed vibrational frequencies were calculated, and the frequencies attributed to ν(CO) were plotted against the solvent electron acceptor, number. A dual‐trace plot was observed. These traces were attributed to extrinsic interactions involving both the carbonyl oxygen and the aldehydic hydrogen in solvents of low acceptor number and predominantly the carbonyl oxygen in solvents of high acceptor number. The spectrum of molten 4‐(dimethylamino)benzaldehyde was used to predict an acceptor number of 14 for this molecule. This value was used to differentiate between high and low acceptor numbers for the solvents used

ISSN:0377-0486    

DOI:10.1002/jrs.1250210107

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe design of a line‐scanned micro Raman spectrometer is described which uses a cooled, slow‐scan, chargecoupled device imaging detector to obtain sequences of Raman spectra from aca.100‐μm long line on a sample. The prototype design has a spatial resolution of<10 μm and a spectral resolution of 4 cm−1. Applications of the instrument to the analysis of mixed TiO2powders and the components of a zircon mineral are

ISSN:0377-0486    

DOI:10.1002/jrs.1250210108

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractSurface‐enhanced Raman (SER) spectra of water‐soluble proteins (lysozyme and bovine serum albumin), dipeptides and amino acids were analysed. Chemisorption is a necessary condition for the appearance of SER spectra on silver electrodes and hydrosols for these compounds. The Raman cross‐section enhancement per molecule may reach a factor of 105–106, depending closely on the frequency of the vibration band considered. The mechanism of enhancement has a short‐range character and is attributed to the π‐electron complexes of the aromatic amino acids side‐chains and σ‐complexes of the molecular groups containing unshared electron pairs with the metal. The effect of induced optical activity in the visible region for aromatic amino adsorbed by silver hydrosols ha

ISSN:0377-0486    

DOI:10.1002/jrs.1250210109

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractSurface enhanced Raman (SER) spectra of bacteriorhodopsin (BRh) in the purple membranes ofHalobacterium halobium, rhodopsin (Rh) in the photoreceptor dises of rod outer segments and complexes of Rh with monoclonal antibodies and photoreceptor dises closed with the cytoplasmic surface inwards were analysed. After adsorption of the membrane proteins on silver electrodes treated via an oxidation‐reduction cycle (ORC) and on unaggregated silver hydrosols with a mean particle diameter about 15 nm, the short‐range enhancement mechanisms was shown; it may be used to study the topography of the membrane‐bound complexes. In this case adsorption prevents photoinduced conformational transitions of the pigments. If the BRh or Rh molecules are adsorbed on partially aggregated hydrosols with a characteristic particle size aout 100 nm or on “smooth” (i.e. not roughened by the ORC) electrodes, the SERS mechanism has a longer range character. Hence it is possible to detect SER spectra which are similar to those obtained in solution but at concentrations two to three orders of magnitude lower. Under such conditions adsorption does not influence photochemical transformations of bacterial and visual rhodopsins. The potential variation on the “smooth” electrode near the zero charge for silver is accompanied by accumulation of K610, the kinetic intermediate of the BRh photocycle. At the same time, the content of the main form, BRh5

ISSN:0377-0486    

DOI:10.1002/jrs.1250210110

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe influence of thermally excited vibrations on vibronic spectra (absorption, CARS excitation profile and resonance background) has been modelled for polyatomic molecules in solution. It is shown that for a model describing some polymethine compounds, the spectra depend only slightly on temperature except in the case of a resonance background and an excitation profile of vibrations with a relatively high value of the origin shift parameter (Δ>1). The investigations of low‐frequency vibrations by resonance CARS to giving information about some molecular parameters is propos

ISSN:0377-0486    

DOI:10.1002/jrs.1250210111

出版商:John Wiley&Sons, Ltd.    

年代:1990

数据来源: WILEY