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The theory of stepwise electron and laser excitation of atoms. I. Weak optical excitation case

C J Webb, W. R. MacGillivray, M. C. Standage

A theory of stepwise excitation of atoms in which electron excitation is followed by single-mode laser excitation is presented. Theoretical expressions are developed using density matrix techniques for line polarisations, excitation cross sections and electron-photon coincidence signals applicable to both axial and planar symmetry stepwise excitation experiments.

Journal of Physics B Atomic and Molecular PhysicsApr 28, 198410 citations

POLARIZATION OF ATOMIC LINE RADIATION. II. OPTICAL EXCITATION AND ITS RELATIONSHIP TO ELECTRON IMPACT EXCITATION.

Hans Kleinpoppen, R. Neugart

Jan 1, 19670 citations

Spin-Dependent Orientation Propensities Revealed in Polarized-Electron–Polarized-Photon Coincidence Studies

N. Andersen, Klaus Bartschat, John T. Broad +2 more

The density matrix parametrization of collisionally excited atomic ensembles is generalized to account for a projectile spin. The elements are related to the ``generalized Stokes parameters'' of Andersen and Bartschat [J. Phys. B 27, 3189 (1994)], determined in scattered-projectile--polarized-photon coincidence experiments after impact excitation by spin-polarized electrons. The well-established orientation propensity rule for unpolarized electron beam experiments is not valid for spin-resolved collisions.The density matrix parametrization of collisionally excited atomic ensembles is generalized to account for a projectile spin. The elements are related to the ``generalized Stokes parameters'' of Andersen and Bartschat [J. Phys. B 27, 3189 (1994)], determined in scattered-projectile--polarized-photon coincidence experiments after impact excitation by spin-polarized electrons. The well-established orientation propensity rule for unpolarized electron beam experiments is not valid for spin-resolved collisions.

Physical Review LettersJan 8, 199624 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.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 PhysicsNov 28, 199733 citations

INTENSITY BEATS IN RESONANCE RADIATION AND ABSORPTION DUE TO COHERENT EXCITATION OF ATOMS BY ELECTRON IMPACT.

T. Hadeishi

Mar 13, 19670 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.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 PhysicsApr 1, 19961 citation

Coherent and incoherent excitation of atoms by electron impact

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Coherent and incoherent excitation of atoms by electron impact

Abstract

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