摘要:

AbstractA series of very sharp bands at ca. 50 cm−1have been observed in the low frequency surface Raman spectra of tungsten and nickel in air and in vacuum (10−5torr) which probably originate in a surface layer of adsorbed molecu

ISSN:0377-0486    

DOI:10.1002/jrs.1250030102

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe fluctuation‐dissipation method of theoretical investigation of stimulated Raman scattering (RS) by polaritons in piezoelectric crystals under nonstationary conditions taking into account both wave and local nonstationary cases in the fixed pump field approximation has been carried out. The method is based on solving the reduced operator equations in partial derivatives for Stokes and polariton fields coupled by the pump field. The equations contain the noise sources – polariton fluctuations whose properties are defined by the fluctuation‐dissipation theorem. The Stokes and polartion field are described in the quantum language as the operators in Heisenberg representation. Quantum description of fields is necessary for correct account of the initial fluctuations and is also essential for the right transition to the particular case of spontaneous RS. The energy characteristics, which describe the angular‐frequency distribution of Stokes and polariton radiation are calculated by means of quantum statistical averaging of the corresponding field combinations. Their general connection with the correlative functions, which define initial and boundary field fluctuations i

ISSN:0377-0486    

DOI:10.1002/jrs.1250030103

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe theoretical investigation of stimulated Raman scattering (RS) by polaritons under nonstationary conditions, when local or wave nonstationary properties are separately important has been carried out on the basis of a fluctuation‐dissipation method. General experssions are found which describe the scattered radiation (Stokes and polariton) nonstationary angular distribution at the piezo‐electric crystal scattering layer exit face. In particular, for the local nonstationary case, the detailed analysis of the cases of small stationary gain and of very short and moderately short pump pulses at large stationary gain is carried through. For small stationary gain and also in the case of very short pulses with arbitrary gain, the spontaneous RS regime is realized, the Stokes wave intensity time dependence being on the whole a purely parametric one. The delay effects connected with the finite nature of the scattering polaritons' relaxation time become significant when the coherent component of the polaritons is important. Typical numerical calculations of the scattered radiation pulse shape and peak intensity are carried out for pump pulses of the rectangular and domed form. The most important general manifestations of nonstationary properties of the polariton RS are the apperance of deformation, asymmetry and delay of the scattered radiation pulses relative to the pump pulses; the angular tuning of the pump duration and the scattered radiation frequency tuning; the different character of the influence of local and wave nonstationary properties and so on. These effects are determined by shape and duration of the pump pulses and also by the stationary gain parameter in the material and by the scattering polaritons' relaxation time (for the local nonstationary case) or by the group delay time of the Stokes wave relatively to the pump wave (for the wave nonstationary ca

ISSN:0377-0486    

DOI:10.1002/jrs.1250030104

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractNew devices, have been developed to generate maps or images of heterogeneous samples using a characteristic Raman frequency line and to obtain the surface distribution of a given compound.Samples are illuminated by a laser beam causing Raman lines of the different substances to be emitted. Different techniques using a triple monochromator or a holographic grating system are described. Several examples of Raman images of heterogeneous samples are presented.

ISSN:0377-0486    

DOI:10.1002/jrs.1250030105

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractRaman spectra of baker's yeast tRNA in NaCl aqueous solutions were measured as a function of sodium ion concentration throughout the 0–1.0Mrange. Strong variations in intensity of the various bands allowed observation of the ionic strength‐dependent conformational transitions of the tRNA. The experimental data obtained point to the existence of five distinct conformations of the tRNA molecules in the range of Na+concentration investiga

ISSN:0377-0486    

DOI:10.1002/jrs.1250030106

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe Raman spectra of AMP and UMP have been taken as a function of the laser excitation wavelength at 5145 Å, 4880 Å, 4579 Å, 3638 Å, and 2572.5 Å (the first harmonic of 5145 Å). The Raman bands of adenine which decrease in intensity upon base stacking or base ordering are shown to derive their intensity largely from the ultraviolet absorption band at 2600 Å which also decreases in absorption strength upon base stacking or base ordering (hypochromism). These bands show a strong resonance Raman effect (RRE) with 2572.5 Å laser light. These results are in agreement with the suggestion of Tomlinson and Peticolas [1] that Raman hypochromism is largely derived from UV hypochromism. The hypochromic Raman band of uracil at 1230 cm−1is shown to derive its intensity from the hypochromic UV band at 2050 Å. None of the bands of uracil appear to show RRE when 2572.5 Å laser radiation is used.One or two Raman bands in adenine which are not strongly hypochromic show RRE at 2572.5 Å. These bands appear to come from vibrations which have Raman tensors that derive their intensity from higher UV bands as well as the

ISSN:0377-0486    

DOI:10.1002/jrs.1250030107

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractSolid‐state and solution IR and laser Raman spectra have been recorded for bromotetracarbonylnitrosyltungsten (I), W(CO)4(NO) Br, in the CO and NO stretching regions and in the region below 750 cm−1. The vibrational data are consistent with atrans‐C4vsymmetry for the complex and assignments have been proposed on the basis of this geometry. The assignments for the CO and NO stretching regions, including those for the weak satellite peaks due to W(12CO)3(13CO) (NO) Br (present in 4% natural abundance), have been verified by an energy‐factored force field calc

ISSN:0377-0486    

DOI:10.1002/jrs.1250030108

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe rotation‐vibrational Raman spectra of thev4(B1)‐,v10(E)‐ and 2v 110‐bands of allene‐h4have been obtained. A ground state combination difference analysis ofv10yields the ground state constantsA0−B0= 4.5147 ± 0.0012 cm−1andDK0= (1.12 ± 0.10)·10−4cm−1. A number of upper state constants for the vibrational levelsv4,v9

ISSN:0377-0486    

DOI:10.1002/jrs.1250030109

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractA technique for separating the Rayleigh scattering from the quasielastic Raman scattering in aqueous solutions is developed. Results are presented for a series of solutions of lithium chloride.

ISSN:0377-0486    

DOI:10.1002/jrs.1250030110

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe Raman spectra of methyl‐dichloro‐sulphonium hexachloroantimonate was studied, both in the solid state and in acetonitrile solution. Polarization measurements were made for the solution and an assignment of the observed frequencies is given and discus

ISSN:0377-0486    

DOI:10.1002/jrs.1250030111

出版商:John Wiley&Sons, Ltd.    

年代:1975

数据来源: WILEY