摘要:

Dipole relaxation of a sphere and of a spherical region in surrounding dielectric are calculated by Zwanig's methods, using his assumed distribution function equation for Brownian motion and a modified one based on Kirkwood's transport theory. The latter is shown to give no new relaxation time from dipole forces and to give functions consistent with Glarum's relation but not with ones derived from cavity models.

ISSN:0026-8976    

DOI:10.1080/00268977400100021

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

E.S.R. spectra of phosphorescent aromatic molecules in frozen solution present, forg≲ 2, a line arising from absorption of two microwave quanta. We show how the resonance field may be computed for any molecular orientation. We find the value of the stationary resonance field and we demonstrate that the transition probability goes through a maximum for the same field value. We give a perturbation treatment followed by an exact derivation of this property. When the electron spin couples strongly enough to the nuclei, we record hyperfine structure in the two-quantum peak. We also analyse this phenomenon theoretically. For an axial hyperfine tensor we are able to account for the observed lineshape, thereby confirming our treatment of the stationary resonance.

ISSN:0026-8976    

DOI:10.1080/00268977400100031

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A formulation in terms of projection operators of the Van Vleck trans-formation is presented. Explicit formulae through eighth order are given, and the eleventh order may be reached fairly simply. Such high orders are relevant for the Born-Oppenheimer separation. It is proved that the Van Vleck transformation conserves symmetry. A special formulation is given for product spaces. The Foldy-Wouthuysen transformation is treated as an example.

ISSN:0026-8976    

DOI:10.1080/00268977400100041

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The problem of the theoretical description of the onset of molecular rotation in crystals is discussed. A particular model based on an effective one-molecule potential function is elaborated and it is suggested that it should be of wide application. The model is applied to solid hydrogen and qualitative agreement found with the behaviour of the phase transition with respect to temperature, pressure and ortho-hydrogen concentration.

ISSN:0026-8976    

DOI:10.1080/00268977400100051

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The Green's function method is utilized to obtain a modified treatment of Fano's line-shape problem which takes into account the coupling between different states in the continuous (or quasi-continuous) non-radiative manifold due to their interaction with the same radiation field states. A new expression for the absorption line-shape is obtained in the form σa(∈)∞[(∈+qYL)2+ (YLq2+ 1)(1 -YL)]/(∈2+ 1), where ∈ is the reduced energy parameter,qis Fano's line-shape index andYLis the non-radiative quantum yield obtained when the non-radiative manifold is optically forbidden. AsYLis always smaller than unity, the absorption never strictly vanishes in contrast to the result obtained in Fano's approximation. In addition, expressions are obtained for the emission line-shape and for the (energy dependent) emission quantum yield within a Fano resonance. The quantum yield so obtained is free from the singular behaviour which characterizes the same quantity obtained in Fano's approximation.

ISSN:0026-8976    

DOI:10.1080/00268977400100061

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Electron density operators and projection operators are fundamental quantities in the general physical interpretation of quantum theory. In this series of papers the aim is to explore their relevance to the definition and use of chemical valence concepts. Here, the problems involved in defining the charge on an atom in a molecule are discussed, and a new approach is formulated in terms of these operators.

ISSN:0026-8976    

DOI:10.1080/00268977400100071

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

In the E.S.R. spectra of K pyrazine in dimethoxyethane asymmetries are observed which are attributed to second order shifts of the nitrogen hyperfine lines. From a detailed analysis of the line shapes it follows that these shifts should be attributed to an ion pair in which the potassium ion is localized symmetrically with respect to the two nitrogen nuclei. The E.S.R. spectra cannot be explained by migration of the cation between two equivalent sites. The spectra at low temperatures indicate the presence of a rapid exchange reaction between the contact ion pair and a solvent separated ion pair.

ISSN:0026-8976    

DOI:10.1080/00268977400100081

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268977400100091

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The dipole moment of three spherical atoms,μ(R12,R23,R31) is expanded in inverse powers of the interatomic distances and an expression is obtained for the coefficients of the leading terms, which vary asR-10. These coefficients are accurately evaluated for the case of three hydrogen atoms and an estimate is obtained for their values in He3.

ISSN:0026-8976    

DOI:10.1080/00268977400100101

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268977400100111

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor