Breakdown of the Dipole Approximation in Soft-X-Ray Photoemission

Document Type

Article

Publication Date

10-1999

Publication Title

Journal of Electron Spectroscopy and Related Phenomena

Publisher

Elsevier

Volume

100

Issue

2021-01-03

First page number:

297

Last page number:

311

Abstract

Although breakdowns in the dipole approximation in the soft-X-ray photon-energy range (hν≤5 keV) were first observed 30 years ago and have been studied theoretically for many years, their significance at low energies has remained generally unappreciated within the broader photoemission community. Advances in gas-phase photoemission experiments using synchrotron radiation have recently highlighted nondipole effects at relatively low energies while probing the limits of the dipole approximation. Breakdowns in this approximation are manifested primarily as deviations from dipolar angular distributions of photoelectrons. Detailed new results demonstrate nondipolar angular-distribution effects are easily observable in atomic gases at energies well below 1 keV, and, in molecules, a previously unexpected phenomenon greatly enhances the breakdown of the dipole approximation just above core-level ionization thresholds. A progress report on this newly burgeoning area from an experimental perspective is presented here, including a brief history, a description of recent advances, graphical representations of nondipolar angular distributions, a re-evaluation of the classic first experiment in the soft-X-ray range and a look to the future.

Controlled Subject

Angular distribution (Nuclear physics); Electron spectroscopy; Photoemission; Synchrotron radiation

Disciplines

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

Language

English

Comments

Also published in:

Advanced Light Source Compendium of User Abstracts and Technical Reports 1998, August 1999

Permissions

Use Find in Your Library, contact the author, or use interlibrary loan to garner a copy of the article. Publisher copyright policy allows author to archive post-print (author’s final manuscript). When post-print is available or publisher policy changes, the article will be deposited.

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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