摘要:

AbstractThe paper gives a historical account of the discovery of the Raman Effect, starting from Raman's voyage to Europe through the Mediterranean Sea in the summer of 1921 to the observation of modified lines in benzene when illuminated by the 435.8 nm radiations of mercury, through a direct vision spectroscope, on 28 February 1928. The important contributions of Raman and his students during the period which form the progressive stages in the road to discovery have been briefly touched upon. The work of the French group, the Russian group and the theoretical work of Smekal are narrated in sequence.

ISSN:0377-0486    

DOI:10.1002/jrs.1250100103

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe advantages of performing coherent Raman spectroscopy with definite input and output polarizations are reviewed. Methods are described for evaluating Raman susceptibility tensor elements, depolarization ratios and nonresonant contributions to the third order nonlinear susceptibility. A systematic development of the signal‐to‐noise ratio reveals the advantages of incomlete suppression of the nonresonant background signal. Results obtained using coherent Stokes and anti‐Stokes Raman spectroscopy, the Raman‐induced Kerr effect and four‐wave mixing are also reviewed with emphasis on liquids a

ISSN:0377-0486    

DOI:10.1002/jrs.1250100104

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe ferroelectric soft mode in the single crystals of the lead germanate system with silicon doping has been analysed by using the following three response functions χ(ω): (1) χ(ω)−1= ω 02− ω2− iγω, (2) χ(ω)−1= ω 02− ω2− ω2− iγ2and (3) χ(ω)−1= ω 02− ω2− iδ2ωτ(1 + ω2τ2)−1. The least squares fitting to the observed spectra showed that the response function of type (3) proposed by Yacobyet al.gave the satisfactory results to the soft mode theory with τ−1≈ 30 cm−1. The temperature dependence of the soft mode frequency and the mode strength has the Curie–Weiss form close to the Curie temperature. The increase of the silicon impurity lowers the soft mode frequency, while the effects on the line width are small. The soft mode frequency seems to be mainly influenced by the change of the short range harmonic force due to the silicon doping. The Curie temperature estimated from the soft mode frequency is con

ISSN:0377-0486    

DOI:10.1002/jrs.1250100105

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractA theoretical study of time‐resolved Raman scattering by a highly photoexcited semiconductor plasma is developed. The scattering cross‐section is calculated using the Zubarev non‐equilibrium ensemble method to describe the macroscopic evolution of the far from equilibrium plasma. Numerical results appropriate for GaAs are presented as an illustr

ISSN:0377-0486    

DOI:10.1002/jrs.1250100106

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractResonant vibrational Raman measurements of the O 3−ion modes in γ‐irradiated Cd(ClO3)2single crystals are reported. It is concluded that the O 3−ions occupy only one non‐equivalent site in the host lattice, in accordance with the ESR measurements previously reported. Resonance enhancement of the fundamental mode and its overtones as a function of the exciting wavelength is also investigated. The activation energy is determined by a simple direct

ISSN:0377-0486    

DOI:10.1002/jrs.1250100107

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractUsing Raman spectroscopy we have studied some effects of the 4felectron–phonon (magnetoelastic) coupling in CecNd1–cF3(0 ≤c≤1). This coupling manifests itself in the splitting of some twofold degenerate phonons in a magnetic field, accompanied by a reduction in linewidth, and in a zero‐field shift of phonon frequencies all depending onc. We have also studied the low lying (electronic) crystal field states of Nd3+(4I9/2) in NdF3and determined the eigenfunctions which have been used for a theoretical interpretation of the magnetoelastic effect

ISSN:0377-0486    

DOI:10.1002/jrs.1250100108

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe Raman spectra of gaseous, liquid and solid CH3PF2and the infrared spectra of the gas and solid have been recorded (3200–20 cm−1). The assignment of the 15 fundamentals is given and discussed and is based on the gas phase infrared band contours, depolarization values and group frequencies. A normal coordinate calculation was carried out by utilizing a modified valence force field to calculate the frequencies and the potential energy distributions. Extensive mixing was found between the PF2stretching and CH3rocking modes. The methyl torsion was observed at 192 cm−1in the far‐infrared spectrum of the gas and from this frequency a three‐fold barrier to internal rotation of 1.74 kcal mol−1was calculated. This value is compared to similar quantities in several other group VA compounds and the observed trends are consistent with those for the corresponding group IV

ISSN:0377-0486    

DOI:10.1002/jrs.1250100109

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractWe present an approximate expression for the electronic Raman scattering intensity of localized impurities, and we employ this result in a simple model of intermediate valence compound with a hybridization term of the Anderson type. We have calculated the relevant time correlation functions using a Green's function technique. Using the published estimates ofp, the probability of finding a Sm ion as Sm3+, determined from the lattice parameters, we were able to compare our expression for the Raman linewidth with published measurements of the linewidth in Sm1–xYxS. The theoretical dependence of the linewidth withxat 300 K gives only qualitative agreement with experiment. Out theory reproduces fairly well the independence of the line shape when samples with 0.15

ISSN:0377-0486    

DOI:10.1002/jrs.1250100110

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractThe vibration‐rotation Raman spectra of the oxygen species18O2,17O18O,17O2and16O2have been recorded and analysed; the spectra of the17O18O and17O2species are reported for the first time. TheB0and α values from these analyses were used to calculate values for the equilibrium‐state rotational constants,Be, and hence the bond lengths,re. The following values were obta

ISSN:0377-0486    

DOI:10.1002/jrs.1250100111

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY

摘要:

AbstractWhen a crystal is subject to a uniaxial stress, the Raman spectrum of various phonons may exhibit changes in the scattering intensity and also shifts of the frequencies and splittings of the degeneracies of the optical phonons. Valuable information can be obtained from such studies regarding the electronic band structure, the scattering mechanism, and the elastic and lattice‐dynamical properties of the material. The basic theoretical and experimental facts related to such effects are briefly reviewed in this contribution. Other possibilities are also discussed which demonstrate the usefulness of a uniaxial stress as a controlled perturbation in the study of crystalline matter by use of light scattering technique

ISSN:0377-0486    

DOI:10.1002/jrs.1250100112

出版商:John Wiley&Sons, Ltd.    

年代:1981

数据来源: WILEY