摘要:

AbstractDans le cadre de ‘l'approximation de réflexion’, les auteurs proposent une expression analytique du tenseur de diffusion des molécules diatomiques et polyatomiques, valable quelque soit la fréquence excitatrice. L'influence de la symétrie des vibrations sur les intensités des raies Raman de résonance est mise en évidence. L'expression du tenseur Rayleigh permet de justifier la forme gaussienne des courbes d'absorption des molécules polyatomiques. L'importance relative des intensités des différents harmoniques est ensuite étudiée en relation avec le coefficient d'absorption. D'autre part, un développement asymptotique permet de retrouver les résultats des théories antérieures de l'effet Raman de prérésonanceEn appendice, on montre enfin comment, à l'aide du formalisme utilisé, on peut déterminer très simplement le tenseur de diffusion Raman de prérésonance des raies f

ISSN:0377-0486    

DOI:10.1002/jrs.1250020302

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe results of an experimental investigation of the twofold degenerate vibrations in calcite (Eg‐type; phonon frequency ΩE/2πc= 721 cm−1) by means of active spectroscopy method, including a new modification of this method are reported. Beating of a biharmonic pump consisting of Nd: YAG laser radiation and tunable (narrow band or broad band) radiation from an optical parametric oscillator (OPO) was used to excite coherent optical phonons above the thermal level. Scattering of the second harmonic of Nd: YAG was used to detect these coherent vibrations. The components of the Raman scattering tensor forEgphonons and the absolute sign of χ NR1122the component of the nonresonant cubic electronic susceptibility were

ISSN:0377-0486    

DOI:10.1002/jrs.1250020303

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

摘要:

AbstractA Czerny‐Turner spectrograph is described in which an image intensifier is positioned in front of the photographic plate. This system shows a large gain in sensitivity over conventional spectrographs without serious loss of resolution. The reciprocity failure of this detection system is found to be very lo

ISSN:0377-0486    

DOI:10.1002/jrs.1250020304

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe low temperature (15K) Raman spectrum of Mn(CO)5Br has been recorded under high resolution conditions in the 2150–1900 cm−1and low frequency (below 700 cm−1) regions using Kr+laser excitation (647.1 nm). The spectrum indicates that there is no phase change between room temperature and 15K. Several Raman‐active CO stretching bands of the principal mono‐isotopic species Mn (12CO)4(13CO)Br present in natural abundance (1% axially substituted and 4% equatorially substituted) have been observed for the first time and assigned on the basis of a CO‐factored force field calculation. The reasons why it is felt that bands due to dilute isotopic species such as13CO are not observed routinely in the Raman, in contrast to the infrared, ar

ISSN:0377-0486    

DOI:10.1002/jrs.1250020305

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

摘要:

AbstractWe here present the results of a Raman investigation on powders and oriented single crysstals of CdIn2S4spinel, nominally pure and doped with Fe.The k  0 fundamental phonon frequencies are: 184 cm−1(Eg), 242 cm−1(F2g), 307 cm−1(F2g) and 362 cm−1(A1g). An additional first order vibration, which is ascribed to a local mode of Fe in tetrahedral sulphur surroundings, is found at 340 cm−1and hasA

ISSN:0377-0486    

DOI:10.1002/jrs.1250020306

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

摘要:

AbstractIf and only if spontaneous resonance Raman scattering is excited by irradiation upon a single, discrete and non‐degenerate energy level sufficiently distant from other levels can it be interpreted as resonance fiuorescence, i.e. a sequence of two independent one‐photon processes, an absorption and an emission in definte order of succession. This decomposition of the resonance scattering process is independent of the bandwidth of the exciting radiation relative to the widths of the combining levels. These widths however determine quantitatively the temporal decay of the resonance scattering (= resonance fluorescence) probability given explicitly in the pa

ISSN:0377-0486    

DOI:10.1002/jrs.1250020307

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe excitation wavelength dependence of the polarized Raman spectrum ofp‐dichlorobenzene single crystal has been measured. The Raman lines of the CC stretching vibrationv2(ag) and the ring breathing vibrationv4(ag) were found to show great intensity enhancements in the tensor component (aa) when the exciting light was shifted to shorter wavelength. With the assumption of the oriented gas model, the intermediate electronic states contributing to the Raman intensities were determined to be the1B3ustates of the molecule. The Raman lines ofv2(ag) andv4(ag) were correlated, from the excitation wavelength dependence of the solution spectrum, to the1B3ustates corresponding to the1B1uand1E1ustates of benzene, respectively. These correlations are explained in terms of the geometrical structures of the molecule in the electronic excited sta

ISSN:0377-0486    

DOI:10.1002/jrs.1250020308

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe depolarization ratios of the CC stretching vibrational Raman lines of C2Cl4, C2HCl3,trans‐C2H2Cl2were measured using visible and UV lasers. The depolarization ratios increased evidently from visible to UV excitation, and were discussed in relation to the ratio of the scattering tensor compone

ISSN:0377-0486    

DOI:10.1002/jrs.1250020309

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

摘要:

AbstractThe behaviour of an element of the Raman scattering tensor is considered as the exciting frequency is tuned through the vibronic absorption spectrum of the scattering molecule. Certain observed features of Raman excitation profiles are explained, and some predictions made. Using some simplifying assumptions, we examine the limiting form of the scattering tensor in certain resonance situations. On the basis of symmetry considerations, we then outline expected variations in (and limits on) the depolarization ratio near resonance.

ISSN:0377-0486    

DOI:10.1002/jrs.1250020310

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY

ISSN:0377-0486    

DOI:10.1002/jrs.1250020301

出版商:John Wiley&Sons, Ltd.    

年代:1974

数据来源: WILEY