Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Physics B Atomic Molecular and Optical Physics

Coherence and correlation in electron-atom collisions

J. A. Slevin, Stanisław Chwirot

Published Jan 28, 1990• 40 citations
Publisher

Abstract

Recent developments in the field of alignment and orientation studies of electron impact excitation of atoms are discussed. The article reviews experiments which have a well defined planar symmetry, i.e. in which the initial and final momenta of electrons are determined. The experimental results obtained by different groups during the last four years are presented after a brief theoretical introduction followed by a description of typical experimental arrangements.

DOI
10.1088/0953-4075/23/2/004

Related papers

Electron-Photon Coincidence Technique for Atomic Collisions

Mevlüt Doğan, Hüseyin Ali Yalım

A brief review is given on development of electron-photon coincidence studies from electron impact of atoms. The theory of electron-photon correlations is outlined in detail in terms of cross sections of excited atoms and excited state charge clouds. The state of a target atom is determined by the various orientation and alignment parameters and the multipole moments of the excited atom. General considerations, such as coherence effects in impact excitation, the influence of fine and hyperfine structures in correlations are taken into account. The relationship between scattering amplitudes (including their phases) and target parameters is worked out for singlet and doublet transitions.

Afyon Kocatepe Üniversitesi Fen Ve Mühendislik Bilimleri Dergisi•Jun 1, 2003•0 citations

Spin-resolved Alignment and Orientation Effects in Atomic Collisions

Klaus Bartschat, N. Andersen

The density matrix parametrisation of collisionally excited atomic ensembles is generalised to account for projectile and target spin polarisations. The density matrix elements, containing spin-resolved alignment and orientation parameters, can be determined by measurements of the 'generalised Stokes parameters' introduced by Andersen and Bartschat (1994) to describe scattered-projectile-polarised-photon coincidence experiments. Focusing on electron impact excitation of light alkali-type targets and mercury, the present experimental status of such experiments is reviewed, in particular with regard to the 'perfect scattering experiment' whereby all independent scattering amplitudes are determined.

Australian Journal of Physics•Apr 1, 1996•1 citation

Complete experiments in electron–atom impact excitation: present status and future prospects

N. Andersen, Klaus Bartschat

An overview is given of the present understanding of excitation in electron–atom collisions, with particular emphasis on the extent to which a "perfect scattering experiment" in the Bederson sense has been achieved. Recent experimental and theoretical results are put into a common framework, generalizing the ideas and systematics, presented in a review paper, of the case of excitation by spin-polarized electron beams. For various levels of complexity, complete sets of coherence parameters are suggested, and their relationships to generalized Stokes parameters and generalized STU parameters are pointed out.

Canadian Journal of Physics•Nov 1, 1996•0 citations

Combining laser and electron interactions – current experiments and future possibilities in excitation and ionization studies

Andrew James Murray

In this brief review a number of different experimental techniques that combine the advantages of laser and electron interactions with atoms and molecules will be described. These processes range from super-elastic electron scattering from laser excited atoms so as to ascertain the electron collision parameters over all scattering geometries, through new electron interactions with laser cooled and trapped atoms, to the process of electron impact ionization of laser-aligned targets. Examples from work carried out in Manchester are given, and new types of measurements that may be possible in the future are described. © 2010 IOP Publishing Ltd.

Journal of Physics Conference Series•Feb 1, 2010•2 citations

Coherence in inelastic low-energy electron scattering

J. A. Slevin

The results of electron-photon coincidence experiments have given a new insight into the excitation of atoms by electron impact. This article reviews the way in which this new experimental technique has provided an exacting and fundamental test for the theory of the excitation process. The basic experimental method is first described, and a comprehensive treatment of excitation of the n 1 P states of helium is given. The extension of the technique to the study of excitation of the n=2 states of atomic hydrogen is then presented. Coincidence measurements also provide information on the role of spin in the collision, and this subject is treated in detail for excitation of heavy atoms by both unpolarised and spin-polarised beams of electrons. Finally, the electron-photon coincidence method permits observation of the time evolution of excited atomic states, and this review describes the attempts made to observe quantum beats in the radiative decay.

Reports on Progress in Physics•May 1, 1984•89 citations

Collisional excitation of atomic D states

N. Andersen, Klaus Bartschat

The description of alignment and orientation for collisional excitation of atomic states by electron and heavy-particle impact, including electron transfer processes, is reviewed. For D states, a new parametrization of the excited atomic ensemble is proposed, and the density matrices describing the excited target state and the light emitted in a subsequent optical decay are expressed in terms of the new parameter set. Recipes for performing complete experiments through scattered-particle - multiple-photon coincidence set-ups are discussed. Because of the difficulties associated with such experiments, attention is also given to the generally incomplete case of scattered-particle - one-photon coincidence arrangements. For D-state excitation, it is demonstrated how the new set of parameters allows for a systematic description of the collision process, and provides opportunities for consistency checks.

Journal of Physics B Atomic Molecular and Optical Physics•Nov 28, 1997•33 citations
Recent developments in the field of alignment and orientation studies of electron impact excitation of atoms are discussed. The article reviews experiments which have a well defined planar symmetry, i.e. in which the initial and final momenta of electrons are determined. The experimental results obtained by different groups during the last four years are presented after a brief theoretical introduction followed by a description of typical experimental arrangements.
A brief review is given on development of electron-photon coincidence studies from electron impact of atoms. The theory of electron-photon correlations is outlined in detail in terms of cross sections of excited atoms and excited state charge clouds. The state of a target atom is determined by the various orientation and alignment parameters and the multipole moments of the excited atom. General considerations, such as coherence effects in impact excitation, the influence of fine and hyperfine structures in correlations are taken into account. The relationship between scattering amplitudes (including their phases) and target parameters is worked out for singlet and doublet transitions.
The density matrix parametrisation of collisionally excited atomic ensembles is generalised to account for projectile and target spin polarisations. The density matrix elements, containing spin-resolved alignment and orientation parameters, can be determined by measurements of the 'generalised Stokes parameters' introduced by Andersen and Bartschat (1994) to describe scattered-projectile-polarised-photon coincidence experiments. Focusing on electron impact excitation of light alkali-type targets and mercury, the present experimental status of such experiments is reviewed, in particular with regard to the 'perfect scattering experiment' whereby all independent scattering amplitudes are determined.
An overview is given of the present understanding of excitation in electron–atom collisions, with particular emphasis on the extent to which a "perfect scattering experiment" in the Bederson sense has been achieved. Recent experimental and theoretical results are put into a common framework, generalizing the ideas and systematics, presented in a review paper, of the case of excitation by spin-polarized electron beams. For various levels of complexity, complete sets of coherence parameters are suggested, and their relationships to generalized Stokes parameters and generalized STU parameters are pointed out.
In this brief review a number of different experimental techniques that combine the advantages of laser and electron interactions with atoms and molecules will be described. These processes range from super-elastic electron scattering from laser excited atoms so as to ascertain the electron collision parameters over all scattering geometries, through new electron interactions with laser cooled and trapped atoms, to the process of electron impact ionization of laser-aligned targets. Examples from work carried out in Manchester are given, and new types of measurements that may be possible in the future are described. © 2010 IOP Publishing Ltd.
The results of electron-photon coincidence experiments have given a new insight into the excitation of atoms by electron impact. This article reviews the way in which this new experimental technique has provided an exacting and fundamental test for the theory of the excitation process. The basic experimental method is first described, and a comprehensive treatment of excitation of the n 1 P states of helium is given. The extension of the technique to the study of excitation of the n=2 states of atomic hydrogen is then presented. Coincidence measurements also provide information on the role of spin in the collision, and this subject is treated in detail for excitation of heavy atoms by both unpolarised and spin-polarised beams of electrons. Finally, the electron-photon coincidence method permits observation of the time evolution of excited atomic states, and this review describes the attempts made to observe quantum beats in the radiative decay.
The description of alignment and orientation for collisional excitation of atomic states by electron and heavy-particle impact, including electron transfer processes, is reviewed. For D states, a new parametrization of the excited atomic ensemble is proposed, and the density matrices describing the excited target state and the light emitted in a subsequent optical decay are expressed in terms of the new parameter set. Recipes for performing complete experiments through scattered-particle - multiple-photon coincidence set-ups are discussed. Because of the difficulties associated with such experiments, attention is also given to the generally incomplete case of scattered-particle - one-photon coincidence arrangements. For D-state excitation, it is demonstrated how the new set of parameters allows for a systematic description of the collision process, and provides opportunities for consistency checks.