摘要:

Recent advances in the dynamics of photochemical isomerization reactions in solution are reviewed. The isomerization reactions in solution show diverse behaviour depending on the nature of the solvent, the viscosity of the solution and the sharpness of the activation barrier. The results of recent time-resolved spectroscopic measurements on several isomerizing molecules in different solvents are discussed. The rate constants of these isomerization reactions lie in the picosecond regime. We briefly discuss the stochastic, Markovian theories of chemical kinetics in solution, including the well known Kramers' theory. Contrary to the traditional belief, recent experiments reveal an apparent breakdown of Kramers' theory atlargeviscosities. This breakdown is most dramatic for isomerizing molecules with sharp barriers. The failure of Kramers' theory for these cases can be traced to the assumption that the solvent forces on reactive motion are delta-correlated in time. We discuss the recent generalization of Kramers' theory by Grote and Hynes who removed the white-noise assumption of Kramers' theory by including the frequency dependence of friction. This generalized theory can qualitatively explain the new experimental data. We also review both experimental and theoretical studies on isomerization reactions in theabsenceof an activation barrier. We discuss why the earlier theory of Forster and Hoffmann is inconsistent, and review the recent theory of Bagchi, Fleming and Oxtoby on isomerization in solution in the absence of a barrier. We also discuss the importance of non-equilibrium solvation dynamics on fast isomerization reactions in solution. Recent computer simulation studies are reviewed. Lastly, we discuss the outstanding problems of this field for future work.

ISSN:0144-235X    

DOI:10.1080/01442358709353399

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Recent advances in gas-phase ion chemistry are discussed. These include theoretical and experimental approaches to ion structure determinations, ion spectroscopy and photodissociation, unimolecular dissociation reactions of polyatomic cations and ion-molecule reactions. Considerable progress in many of these areas of research has come through the experimental use of tandem (MS/MS) mass spectrometers. From the theoretical viewpoint,ab initiocalculations have demonstrated predictive capabilities for ion structure determinations and statistical theories—quasiequilibrium theory (QET) and variational transition state theory (VTST)—are still of great value in treating the dynamics of ionic systems.

ISSN:0144-235X    

DOI:10.1080/01442358709353400

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Unimolecular and bimolecular reactions of alkoxy and alkyl peroxy radicals have evoked considerable interest because of their relevance to both atmospheric chemistry and combustion. In addition to the reactions of these radicals, their electronic spectra and thermochemistry are also considered. In particular group additivity values are tabulated so that the latter values may be calculated.

ISSN:0144-235X    

DOI:10.1080/01442358709353401

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Orbitals, Terms and States. By M. GERLOCH (John Wiley & Sons, 1986.) [Pp. 176.] £7-95. ISBN 047190936 X.

ISSN:0144-235X    

DOI:10.1080/01442358709353402

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor