摘要:

AbstractMicro‐Raman studies were performed on ion‐irradiated oxidized silicon surfaces with different ion energies, ion fluences and subsequent hydrogenation to determine the efficacy and sensitivity for obtaining information on the degree of ion beam‐induced damage in very thin (ca.100 Å) layers of silicon subsurface and the top oxide. The variations in the Raman spectra were interpreted in terms of the degree of amorphization produced in the silicon sub‐surface by the ion beam and depolymerization of the top S

ISSN:0377-0486    

DOI:10.1002/jrs.1250241002

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSpectra of the pyridine–methanol system were recorded in the range 300–3820 cm−1using the technique of four‐channel Raman spectroscopy. The relative concentrations of the two components were varied in different mixtures, such that the mole fraction of pyridine,C, was 0.1, 0.2, 0.3, 0.5, 0.7, 0.8 and 0.9. The isotropic part (Iiso) of the Raman scattered intensity was recorded for all seven mixtures and for pure pyridine (C= 1.0) and pure methanol (C= 0.0) in the region 950–3820 cm−1only, since below 950 cm−1the isotropic part of the intensity was too weak to provide any useful information. The most important aspect of this study was the experimental determination of integrated isotropic intensities in two regions, namely 960–1080 and 2700–3650 cm−1, and the study of their variations with changing concentration of pyridine in the different mixtures. The most striking result was the observation of excess intensity over a linear concentration dependence in the region 960–1080 cm−1. The variations in frequency shifts and line width changes measured from the isotropic part of the Raman spectra of different mixtures in the region 960–1080 cm−1, and especially in the region 2700–3650 cm−1, are discussed with a view to understandin

ISSN:0377-0486    

DOI:10.1002/jrs.1250241003

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe time‐dependent description of resonance Raman scattering of multimode systems is presented and discussed. The basic quantities of the theory are the Fourier transforms of the Raman amplitudes. For a number of vibronic models they are related to the optical absorption. These relationships enable one to transform the absorption spectrum to the Raman excitation profiles. In the transform method, model parameters are needed only for the Raman mode; the multimode information is automatically included via the measured optical absorption. The method holds for an arbitrary temperature. Transform relationships are derived for the basic model of linear vibronic coupling and for more complicated models including linear non‐Condon interaction, frequency shifts and mode mixing with electronic excitation, the Jahn–Teller effect and inhomogeneous broad

ISSN:0377-0486    

DOI:10.1002/jrs.1250241004

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractSurface‐enhanced Raman scattering (SERS) of 2‐phenyl‐1‐ethanethiol was investigated in a silver sol. The molecule was found to be chemisorbed dissociatively on the silver surface by rupture of its SH bond. Although both thetransandgaucheconformers around the C‐1C‐2 axis could exist on the surface with submonolayer coverage, thetransconformer seemed to be dominant as the bulk concentration of the molecule was sufficient for full monolayer coverage. In the submonolayer coverage limit, a gradualtrans‐to‐gauchetransition was found to occur on the surface with increase in borohydride concentration in the sol solution. The vibrational assignment of the molecule in the liquid phase was also refined by

ISSN:0377-0486    

DOI:10.1002/jrs.1250241005

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractRaman spectra were obtained for two different samples of alumina. One is usually used as a support for hydro‐treating catalysts in heterogeneous catalysis and the other was synthesized in the laboratory. Different excitation wavelengths were used: 457.9, 488.0, 514.5, 647.1 and 1064 nm. The commercially available alumina showed an intense broad background with excitation in the near‐infrared region, whereas no significant background was observed with visible excitation. The synthetic alumina showed a broad background band with laser excitation in the visible region. It is shown that the appearance of these backgrounds is not due to fluorescent impurities (e.g. iron, chromium or organic compounds). Tentative explanations of the spectral features are provided in terms of density of states (alumina A) or bulk hydroxyl groups (alumina

ISSN:0377-0486    

DOI:10.1002/jrs.1250241006

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractA scattering model of interference between the Franck–Condon and Herzberg–Teller terms was studied in the preresonance regions of hyper‐Raman spectroscopy. It is shown how profound antiresonance effects are connected with molecular properties such as potential curve displacement and vibronic coupling param

ISSN:0377-0486    

DOI:10.1002/jrs.1250241007

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractNear‐infrared Fourier transform (NIR‐FT) Raman and surface‐enhanced Raman spectroscopic (SERS) techniques were used in studies of the vibrational spectrum of 9‐methoxy‐2‐N‐methylellipticinium chloride. NIR‐FT‐Raman spectra were obtained on the powder and SER spectra were measured in silver colloids using dilute aqueous solutions of the drug (2 × 10−6M, pH 7.5). Some Raman bands in the SER spectrum show increased relative intensities compared with the corresponding bands in the NIR‐FT‐Raman spectrum, whereas other bands show decreased relative intensities. A general valence force field was used in the calculation of the potential energy distribution of the vibrational modes. This calculation reveals that bands from the indole moiety of the molecule show intensity enhancements, whereas bands arising from modes localized in the isoquinolinium part of the molecule show decreasing intensities in the SER spectra. These results strongly indicate that the indole part of the molecule is close to or attach

ISSN:0377-0486    

DOI:10.1002/jrs.1250241008

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractRaman spectra of aqueous HX solutions (X = F, Cl, Br and I) were measured in botl: the liquid and glassy states. It is shown that the preresonance Raman effect is the major factor for the intensity increase in the Raman spectra with increase in halide concentration. The general spectral features are essentially the same as those for aqueous LiX solutions when the contributions of oxonium ions are excluded. The Raman bands of oxonium ions were observed better in the Raman spectra of glassy HX solutions.

ISSN:0377-0486    

DOI:10.1002/jrs.1250241009

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe surface‐enhanced resonance Raman and surfaces enhanced hyper‐Raman (SERHR) spectra of a photochromatic indigoid dye were obtained. The influence of stationary additional lighting (AL) at the absorption bands of the photoisomers on the SERHR intensities was observed. This is connected not only with the changes in the photoisomer concentration on the silver surface under AL but also with different scattering intensities of the resonance hyper‐Raman spectra of isomers due to their different symme

ISSN:0377-0486    

DOI:10.1002/jrs.1250241010

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe Raman spectra of aqueous vanadium (V) solutions at different pH values, ranging from 13.1 to 7.0, are presented. The dominant bands in the range 700–1100 cm−1are assigned to the VO symmetrical stretching of the different oligomers, using additional information from51V NMR spectra and empirical models. The effects of pH, concentration and ionic strength on the oligomerization equilibria are discussed. The ionic strength is found to affect significantly the oligomer composition of vanadate solutions, which is of interest in biochemical and biological stud

ISSN:0377-0486    

DOI:10.1002/jrs.1250241011

出版商:John Wiley&Sons, Ltd.    

年代:1993

数据来源: WILEY