摘要:

Photoelectron kinetic-energy spectra of resonant multiphoton ionization of gaseous molecules are regarded as ‘photoelectron spectra of the resonant intermediate excited states’. Therefore, such a technique using resonant multiphoton ionization or stepwise ionization with a tunable pulse U.V./visible laser makes it possible to observe excited-state photoelectron spectra for various molecules and molecular complexes in the gas phase. Molecular nonradiative electronic states for which direct observation is difficult by fluorescence spectroscopy can be studied by this technique. It is possible to study not only static but also dynamic aspects of various molecular excited states from the point of view of photoelectron spectroscopy. In this sense, such photoelectron spectroscopy may be called ‘dynamic photoelectron spectroscopy’. This is in striking contrast to VUV photoelectron spectroscopy which is mostly concerned with static aspects of ground-state molecules, although information on the dynamics of ionization processes can be obtained. Molecular dynamic photoelectron spectroscopy will be fruitful especially for studying dynamic aspects of molecular excited states from the photophysical and photochemical points of view. The present article is concerned mainly with dynamic photoelectron spectroscopy and its application to molecular processes such as photodissociation, autoionization, and intramolecular relaxation.

ISSN:0144-235X    

DOI:10.1080/01442358709353405

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

We describe the basic methodologies and applications of computer modelling methods applied to the simulation of silicates and aluminosilicates. We discuss the use of distance least squares (DLS), electrostatic, Born-model and quantum mechanical methods. We consider applications to the simulation of the structures and defect properties of silicates. We include discussions of recent work on zeolites and on Mg2Si04.

ISSN:0144-235X    

DOI:10.1080/01442358709353406

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Potential energy hypersurfaces are now most frequently represented by the location and characterization of their stationary (critical) points. Model studies have demonstrated that hundreds of stationary points can be present on some potential hypersurfaces of chemical interest. Any structure-dependent observed quantity can thus have a convolutional nature, being composed of contributions of relevant stationary points. This article focuses on equilibrium and rate processes; it deals with situations in which component of an equilibrium is represented by a group of several different local energy minima and/or when several different saddle points serve as activated complexes in a single rate process. Particular attention is paid to the case where two or more isomeric structures of comparable stability coexist, the isomers being indistinguishable under observational conditions. Evaluations of overall, convolutional standard and/or activation reaction terms based on the stationary-point hypersurface representation are discussed with emphasis on theory-observation comparisons, experiment interpretation, and prediction of behaviour.

ISSN:0144-235X    

DOI:10.1080/01442358709353407

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

Positron Annihilation: Proceedings of the Seventh International Conference on Positron Annihilation, New Delhi, India, January 1985. Edited by P. C. Jain, R. M. SINGRU and K. P. GOPINATHAN. (World Scientific, 1985.) [Pp. 1048-f xliii.] £124-20. ISBN 0971978393.

ISSN:0144-235X    

DOI:10.1080/01442358709353408

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor