摘要:

An approximate method of estimating the electric polarizability of atoms is considered. The influence of the polarization of one electron state on others is described in terms of induced effective fields. Parameters involved in the model are (i) uncoupled polarizabilities αifor electron states of typesi, (ii) quantities ξirelated to the induced field at the nucleus due to the polarization ofi, and (iii) reduction factors βijfor the induced effective fields from the polarization of statesjacting oniwhenidoes not lie completely insidej. Simple methods of estimating the parameters αiand ξiare given, but the most significant feature of the paper is its method of finding the reduction factors βij. After the parameters are calculated, a set of coupled linear equations determines the effective fields acting on the various types of electrons. The Ba atom is discussed as an illustration. It is found that the ratios to the applied field of the total effective fields acting on 6s, 5p and 5s electrons are 0·52, -0·56 and 0·96 respectively, and that the polarizability α=35 Å3, in fair agreement with the experimental value α = (39·7 ± 3·2) Å3. Results for He, O, Ar and Gd are also given.

ISSN:0026-8976    

DOI:10.1080/00268977700101981

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Thev3Raman band of CD4has been recorded with a resolution of about 0·25 cm-1. This spectrum has been analysed in conjunction with recent high-resolution measurements of the corresponding infra-red band. The following ground-state constants were obtained:Bo=2·63264±0·00013 cm-1,Do=2·74±0·15 × 10-5com-1. The upper-state constants have also been revised in minor respects. The final weighted r.m.s. deviation between experimental and theoretical peak wavenumbers is 0·009 cm-1for 162 Raman lines.

ISSN:0026-8976    

DOI:10.1080/00268977700101991

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Un mod`ele théorique est proposé en vue d'analyser l'influence de la température sur les spectres infrarouge et Raman des molécules diatomiques en solutions inertes. Les fluctuations vibrationnelles et rotationnelles sont décrites par les fonctions de corrélation correspondantes. On montre que lorsque la température augmente, les bandes du spectre se déplacent vers la position qu'elles occupent dans le gaz, tandis que la largeur de la composante vibrationnelle diminue. Les limites du mod`ele utilisé sont ensuite discutées.

ISSN:0026-8976    

DOI:10.1080/00268977700102001

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Proton and deuteron longitudinal and transverse relaxation rates were determined for methyl protons and carboxylic deuterons in solutions of poly(methacrylic acid) in D2O. The frequency-dependence of these rates, as obtained in a range of 4–60 and 3·4–9·2 MHz respectively, is analysed in terms of an anisotropic rotational diffusion model. The parameters involved are determined and their temperature-dependence is reported. The results are discussed, together with the methylene deuteron parameters, previously obtained from experiments on H2O solutions of the same polymer.

ISSN:0026-8976    

DOI:10.1080/00268977700102011

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The wetting of a rigid solid by a simple fluid is studied. Using the methods of statistical mechanics an exact expression is obtained for the work of adhesionWA(and hence the contact angle). It is found thatWAconsists of two termsWA(1) andWA(2).WA(1) depends directly on the solid-fluid interaction potential and the fluid one-particle distribution function, and corresponds to the direct interaction between fluid and solid.WA(2) depends directly on the fluid-fluid interaction potential and the fluid two-particle distribution function, and corresponds to the relaxation of the fluid density profile to its free surface form when the liquid is pulled away from the solid. The existence ofWA(2) is the novel feature of this theory. Comparisons with existing theories are made.

ISSN:0026-8976    

DOI:10.1080/00268977700102021

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The nuclear spin symmetry conversion transition, whereby a methyl group changes tunnelling state (A↔E) and total nuclear spin (ΔI= ± 1), is made resonant by the flip of an unpaired electron spin (Δms= ± 1). The coupling between an unpaired electron in a free radical and a methyl group in a nearby molecule is via the inter-molecular spin-spin interaction. The matrix elements and transition probabilities for this transition are calculated explicitly. The motivation behind the calculation is to aid in the interpretation of electron spin relaxation experiments inγ-irradiated 4-methyl-2,6-t-butylphenol where these resonant transitions have a profound effect. The results presented have also been useful in the interpretation of nuclear magnetic resonance experiments in the same substance.

ISSN:0026-8976    

DOI:10.1080/00268977700102031

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

An internally consistent theory of optical scattering in molecular fluids is developed in terms of a ‘screened dipole radiator’ and a screened dipole photon propagator, related by a Bohr-Peierls-Placzek-type relation. The screened dipole radiator describes the propagation of scattered radiation in the dielectric medium, the transition at the surface of the scattering sample, and the ultimate propagation in vacuum outside the material system. The scattering is obtained as a series in terms of Ursell functions, explicit to all orders. In an approximation describing light scattering by matter in bulk, the screened dipole radiator is obtained in closed form involving an intrinsic directional average. The directional average has important consequences for depolarization, for critical scattering, and for questions of convergence.

ISSN:0026-8976    

DOI:10.1080/00268977700102041

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Accurate momentum distributions and Compton profiles of the first-row atoms, B, C, N, O, F and Ne are reported usingab initiowavefunctions of the configuration-interaction type. The effects of electronic correlation are also analysed. Dynamical correlation was found to be insignificant while all-external, semi-internal and polarization terms were found to appreciably modify the momentum density and, to a lesser extent, the Compton profile. Radial correlation appears to affect these properties somewhat less than angular correlation terms. Specific studies were made on neon in order to clarify some conflicting results of previous works.

ISSN:0026-8976    

DOI:10.1080/00268977700102051

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The electric-field-variant (EFV) gaussian basis sets derived from the standard bases involving s and p-type GTO's are used for the calculation of the electric dipole polarizabilities of HF, H2O, NH3, and CH4. The explicit dependence of the basis functions upon the strength of the external electric field leads to a significant improvement of the computed polarizabilities in comparison with the results obtained from the corresponding field-independent bases. The accuracy of the computed polarizabilities and polarizability anisotropies is comparable to that achieved in the best, near-Hartree-Fock perturbation calculations employing much larger polarized basis sets.

ISSN:0026-8976    

DOI:10.1080/00268977700102061

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Energy and wave functions for the ground and lowest excited states of C2H2and C2H2+have been obtained by means ofab-initiovalence bond calculations. The results are compared with the experimental photoelectron spectrum of C2H2.

ISSN:0026-8976    

DOI:10.1080/00268977700102071

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor