摘要:

Previously reported calculations concerned with spin-orbit enhancement of molecularS-Ttransitions have utilized an approximate one-electron spin-orbit Hamiltonian. The approximations are carried over from atomic spin-orbit theory and are justified on the basis of physical reasoning strictly applicable only to diagonal matrix elements. In order to test critically these assumptions, a treatment of spin-orbit enhancement of the formaldehyde3A2↔1A1transition is given using the complete spin-orbit Hamiltonian. A one-electron approximation to the spin-orbit Hamiltonian is found to be conceptually valid. The one-electron approximation which most closely approximates the complete spin-orbit Hamiltonian is the bare nuclear field Hamiltonian. Calculations on the lowest triplet state of the azines yield similar results.

ISSN:0026-8976    

DOI:10.1080/00268976800101341

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A valence electron approximation is examined in which valence shell orbitals are orthogonalized to neglected core orbitals. It is possible to determine approximate upper and lower bounds to that binding energy which would be predicted by an analogous calculation with the same basis orbitals but with all electrons included. This should be useful in estimating molecular binding energies. The example of lithium hydride is discussed in detail.

ISSN:0026-8976    

DOI:10.1080/00268976800101351

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

ISSN:0026-8976    

DOI:10.1080/00268976800101361

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A method for calculating unsaturated slow-passage N.M.R. spectra is presented which differs from conventional procedures in that no energy levels and no wavefunctions have to be computed and that no explicit line-shape function need be specified. It is shown, by developing the theory in the Liouville representation of quantum mechanics rather than in the Hilbert space representation, that it is possible to compress the total information content of an N.M.R. spectrum into two complex vectors, a radiofrequency-independent ‘shape vector’ and a ‘spectral vector’ which is a trivially simple function of the radiofrequency. The absorption spectrum is obtained as the negative real part of the scalar product of these two vectors. The method may be regarded as an extension of the super-operator formalism of Banwell and Primas.

ISSN:0026-8976    

DOI:10.1080/00268976800101371

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A simple expansion is given for the μαβtensor in terms of the normal coordinates.

ISSN:0026-8976    

DOI:10.1080/00268976800101381

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The quantum field theoretical formulation of optical birefringence based upon theSmatrix and the Stokes parameter description of polarization is applied in a study of the birefringence of liquids induced by a static magnetic field. The phenomena treated are the Faraday effect (for an arbitrary ellipticity of the incident beam), the Cotton-Mouton effect and the quadratic Faraday effect in which the angle of rotation of the plane of polarization is proportional to the square of the magnetic field strength and which occurs in solutions of naturally optically active molecules.

ISSN:0026-8976    

DOI:10.1080/00268976800101391

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

The inverse Faraday effect, in which a magnetization is induced in a solution through which is passed a polarized light beam of arbitrary ellipticity, is discussed on the basis of theS-matrix formulation of optical birefringence. It is shown that the Faraday effect and the inverse Faraday effect are topologically identical problems of diagrammatic perturbation theory and so it follows automatically that the magnetization should be proportional to the Verdet constant. The optical Faraday effect is the circular birefringence induced by an intense circularly polarized beam of light propagated colinearly with the weak measuring beam: the electric vector of the circularly polarized beam interacts with the molecule in a way that resembles the interaction of a static magnetic field. The interrelations of these two effects and the normal Faraday effect the self-rotation of the polarization ellipse of an intense beam are discussed.

ISSN:0026-8976    

DOI:10.1080/00268976800101401

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Couplings over four bonds,4JHH, are discussed for compounds where stereochemistry is thought to be the dominant factor determining their values. A simple MO theory [3, 4] provides calculated coupling constants in agreement with experiment. The form of the theory permits an analysis of the mechanisms responsible for long-range coupling. The approach is generalized to include distorted cyclohexane fragments and these results are presented in a graphical form.

ISSN:0026-8976    

DOI:10.1080/00268976800101411

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

Group theoretical methods are used to construct the [AX]4nuclear spin hamiltonian for a system with tetrahedral symmetry. This is used to analyse the fluorine and phosphorus spectra of tetrakis (2-fluoro-1,3,2-benzo-dioxaphosphole) nickel(0). Tables are given which will assist the construction of the spin hamiltonian of any tetrahedral spin system.

ISSN:0026-8976    

DOI:10.1080/00268976800101421

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor

摘要:

A revised expression for the π electron contribution to proton-proton coupling is presented. Calculations using this expression give much smaller contributions than were obtained from the earlier expression of Karplus. Even for coupling over five bonds it is predicted that a significant part of the coupling arises from aσelectron mechanism.

ISSN:0026-8976    

DOI:10.1080/00268976800101431

出版商:Taylor & Francis Group    

年代:1968

数据来源: Taylor