摘要:

In low energy atomic collision processes, the main contribution to the cross section often comes from ‘‘hidden crossings’’ of potential energy curves in the complex internuclear coordinate plane. Ionization of hydrogen by bare proton has been calculated at intermediate energies (E/A=5−25 keV). In addition to total cross section the electron energy spectra are discussed. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50089

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The current status of evidence for saddle‐point electrons is discussed critically. Applications of the saddle‐point model to the Barkas effect, ionizing collisions involving highly‐charged projectiles, and proton‐H collisions are considered. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50099

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Representative experiments reported with regard to the subject of Saddle Emission are reviewed and a critical summary of their evaluation as well as artifacts that could have affected or distorted the experimental results is also given. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50087

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Ionization in atomic collisions at adiabatic impact energies is discussed. Special attention is given to the saddle point ionization mechanism. This mechanism can be described by a quantum mechanical theory based on the concept of hidden crossings. The fundamental H+‐H collision system is studied as a test case. For 1–6 keV collisions both the experimental velocity distributions and the relative total ionization cross sections of this system can be explained by the theory in a consistent way. At collision energies of 4 keV and higher there is strong evidence for the existence of a saddle point ionization mechanism. Saddle point effects in the He2+‐H (theory) and H+‐He (experiment) collision systems are briefly commented upon. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50088

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A theoretical overview of target and projectile ionization in ion‐atom collisions is presented within the framework of the First Born Approximation. The dual role of the electrons in screening and electron‐electron interactions is emphasized, along with the observable consequences of each role. Examples from theory and experiment are given. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50090

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

This lecture will focus on one aspect of electron spectroscopy from ion‐atom collisions. This topic is the ionization of target atoms by highly charged projectile ions. It deals with the overall broad features of electron spectra created by direct ionization and only requires low energy resolution electron spectroscopy. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50091

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Features of the spectra of electrons ejected in ion‐atom collisions which arise due to ‘‘two‐center’’ effects are described. After a brief survey of these effects, they are illustrated in more detail through examples of studies involving intermediate energy collisions. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50092

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The passive (screening) and active (antiscreening) roles of the target electrons in the electron loss process is reviewed. The semiclassical approximation is used to show that the screening and antiscreening modes are related to the form in which the coherence of the various parts of the target electron cloud is considered in the electron loss process. These concepts are applied to projectile electron loss in 2.0‐MeV/u C5++He collisions. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50093

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We analyze the interplay between classical and quantum dynamics in ionization of atoms by fast charged particles. The convergence to the classical limit is studied as a function of the momentum transferred to the electron during the collision, the impact parameter, the energy and angle of the emitted electron, and the initial state of the target. One goal is to assess the validity of exact classical (CTMC) methods and approximate classical models such as the Thomson model. Applications to data for electron ejection at large angles are presented. The connection between collisional ionization by charged particles and ionization by half‐cycle pulses is discussed. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50094

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The close‐coupling method of treating ion‐atom collisions is reviewed and evaluated in terms of the limitations. A new AO‐MO matching method which can be easily generalized to collisions involving multi‐electron systems is described. It is suggested that in the inner region the adiabatic MO approach is replaced by diabatic‐by‐sector MO basis functions. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.50095

出版商:AIP    

年代:1996

数据来源: AIP