Document Type

Article

Publication Date

7-2003

Publication Title

Physical review A

Publisher

American Physical Society

Volume

68

Issue

1

First page number:

012714-1

Last page number:

012714-10

Abstract

We have measured the forward-backward asymmetry of photoelectron angular distributions produced in the vacuum ultraviolet photoionization of helium. This asymmetry, a consequence of the breakdown of the dipole approximation, measures the real part of the ratio of the quadrupole and dipole matrix elements. In the autoionization region, the strong energy dependence of the asymmetry permits an experimental separation of the ratio of those magnitudes from their phase difference. We experimentally determined the Fano parameters of the 2p21D2 quadrupole resonance, and report improved values of the width Γ and line profile parameter q from those previously available from electron scattering. Off resonance, the smooth energy dependence of the asymmetry is found to agree well with the theoretical treatment presented here which incorporates higher multipole effects.

Keywords

Angular distribution (Nuclear physics); Atomic absorption spectroscopy; Conduction electrons; Dipole moments; Nuclear physics; Photoionization

Disciplines

Atomic, Molecular and Optical Physics | Inorganic Chemistry | Materials Chemistry | Nuclear | Physical Chemistry

Language

English

Permissions

Copyright American Physical Society. Used with permission.

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