摘要:

The triplet lineshape is solved analytically for a paramagnetic molecule slow tumbling both in a disordered and an oriented solution. The algorithm takes into account the autoperators of the liouvillian associated with the spin hamiltonian and gives the spectrum as a linear combination of simple terms. As an intermediate result we obtain the lineshape for anS= 1/2 spin system subjected to an axially symmetric Zeeman interaction. An analytical expansion is obtained even if an orienting potential drives the molecular diffusion.

ISSN:0026-8976    

DOI:10.1080/00268978500101501

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Copper complexes are present in many biological systems dissolved in an isotropic or ordered fluid matrix. For such systems E.P.R. lineshape studies in the slow motion region are often incomplete due to both the slowness of simulation programs and inherent approximations in the fitting routines. The aim of this paper is to describe a fast computational procedure for simulating E.P.R. lineshapes of such magnetic species. We take into account, in a very simple way, the angular dependence of the transition probability. Furthermore we criticize carefully the assumption of deleting, in the slow motion regime, the pseudosecular terms.

ISSN:0026-8976    

DOI:10.1080/00268978500101511

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The H3+ab initiopotential energy surface and its analytical representation has been re-examined to promote more accurate vibration-rotation calculations. We present here a new and accurate 78 point PNO-CI grid which predicts the minimum energy geometry to be an equilateral triangle of side,r(H-H)= 1·6525a0. and energy of -1·34188Eh. Of the analytical representations only the sixth order Simons-Parr-Finlan (SPF) and Ogilvie force fields were found to satisfy our fitting criteria, resulting in associated errors of less than 11·1 kJ mol-1. Our calculated vibrational band origins are in good agreement with those of Carney and Porter, with the differences of the lowest-lying vibration states essentially reflecting the analytical characteristics of the potential energy surfaces used.

ISSN:0026-8976    

DOI:10.1080/00268978500101521

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The molecular dynamics simulation of chain molecules with a full atomic description is considered in the particular case of a n-alkane molecule. In order (a) to keep the time step in the numerical integration of the equations of motions to a reasonable value (10-15-10-14s) and (b) to describe such flexible systems with a minimum number of degrees of freedom, it is useful to impose geometrical constraints in order to freeze the fastest intramolecular motions of the chain.

ISSN:0026-8976    

DOI:10.1080/00268978500101531

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A general apparatus is described with which the effects of static magnetic fields and microwave fields on the recombination reactions of radicals may be studied. In the latter case the experiment is of the optically-detected electron spin resonance (O.D.E.S.R.) variety in solution and in principle provides a means for identifying radicals very shortly after they are created. A new method which involves creating the radicals repetitively and adding their successive decay signals, obtained with the field on and the field off, in real time in counterphase is shown to be capable of detecting quite small effects. The method is illustrated with preliminary results obtained from a variety of chemical systems in normal and micellar solutions.

ISSN:0026-8976    

DOI:10.1080/00268978500101541

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The molecular pair correlation functions of liquid H2O have been obtained in the pressure range 1–2000 bar. A strong structural inhomogeneity of liquid water resulting from fluctuations of the entropy and density has been found. This gives rise to a complicated shape of the distribution of the intermolecular distances in the first coordination sphere. The coordination number is equal to approximately 4·4, but not more than 2·5 of the total number of the nearest molecules can form a tetrahedral short-range order.

ISSN:0026-8976    

DOI:10.1080/00268978500101551

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

A classification of the 16 possible dual (syn + anti) 4 donor + 4 acceptor orbital correlation schemes is developed to describe cofacial complexes of benzene, naphthalene, anthracene and pyrene with benzoquinone, chloranil and tetracyanoquinodimethane, belonging toC2vandCspoint groups. None of these forms an exciplex and the type of correlation is not indicative of the preferred donor acceptor orientation in the EDA complex ground state. Although the correlations are not uniquely defined inCssymmetry they provide a basis for identifying adiabatic channels for geminate charge neutralization of radical-ion pairs.

ISSN:0026-8976    

DOI:10.1080/00268978500101561

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

where λ = μ2/d3kT. This series has been examined by various Padé approximant methods. We conclude that the extended series almost certainly sets an upper limit to the absolute magnitude ofC*ϵ, whose true value may well lie close to the estimates provided by Joslin's terms. The opportunity is taken to present a number of mathematical lemmas useful in calculations of this type.

ISSN:0026-8976    

DOI:10.1080/00268978500101571

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Thef-felectronic spectra of aD4coordination compound [Eu(III)(2,2′-bipyridine-N,N′-dioxide)4]3+and ofD3analogues indicate, on comparison, that only the ΔMJ= ±1 component of the quadrupolar Eu(III)7F0→5D2transition is active in theD4case. The intensity of a quadrupolar metal-ion transition in aD4complex is governed uniquely by a single rank-2 environmental ligand tensor, within the restriction to one-electron operators, and it generates a first order electric dipole moment solely for the ΔMJ= ± 1 transition component. A rank-2 ligand tensor cannot arise from a configurational interaction mechanism based upon a static point-charge or dipolar crystal field, nor from the dynamic ligand-polarization mechanism in the mean polarizability approximation. The extension of the latter mechanism to include the polarizability anisotropy of the ligand bonds gives a rank-2 ligand polarization field tensorF(2)0which accounts for the7F0→5D2dipole strength of theD4complex investigated.

ISSN:0026-8976    

DOI:10.1080/00268978500101581

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

It is shown that the free energies associated with the solutions of extended RISM integral equations can be obtained in closed form thus avoiding the necessity of numerical coupling parameter integrations. In addition, variational principles are deduced which provide a basis for efficient algorithms to solve extended RISM integral equations.

ISSN:0026-8976    

DOI:10.1080/00268978500101591

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor