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Phys. Rev. A 69, 022711 (2004) [8 pages]

Double photodetachment from the Cl- ion

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A. Aguilar* and J. S. Thompson
Department of Physics, MS 220, University of Nevada, Reno, Nevada 89557-0058, USA

D. Calabrese
Department of Physics, Sierra College, Rocklin, California 95677, USA

A. M. Covington
Lake Tahoe Community College, South Lake Tahoe, California 95150-4524, USA

C. Cisneros
Centro de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca 62131, Mexico

V. T. Davis
Photonics Research Center, United States Military Academy, West Point, New York 10996, USA

M. S. Gulley
LANSCE Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

M. Halka
Department of Physics, Embry-Riddle Aeronautical University, Prescott, Arizona 86301, USA

D. Hanstorp and J. Sandström
Department of Physics, Chalmers University of Technology and Göteborg University, SE-41296, Göteborg, Sweden

B. M. McLaughlin†
Department of Applied Mathematics and Theoretical Physics, The Queens University, Belfast BT7 1NN, United Kingdom

D. J. Pegg
Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA

Received 25 September 2003; revised 26 November 2003; published 25 February 2004

The correlated process involving the photodetachment of two electrons from the Cl- ion has been investigated over the photon energy range 20–45 eV. In the experiment, a beam of photons from the Advanced Light Source (ALS) was collinearly merged with a counterpropagating beam of Cl- ions from a sputter ion source. The Cl+ ions produced in the interaction region were detected, and the normalized signal was used to monitor the relative cross section for the reaction. An absolute scale for the cross section was established by measuring the spatial overlap of the two beams and by determining the efficiency for collection and detection of the Cl+ ions. The overall magnitude and shape of the measured cross section for this process agrees well with an R-matrix calculation. The calculation identifies the dominant mechanism leading to the production of the Cl+ ion as being a direct nonresonant process involving the ejection of a pair of electrons from the valence shell. Less important is the indirect nonresonant process that involves the production and decay of core-excited and doubly excited states of the Cl atom in an intermediate step. Direct and indirect resonant mechanisms involving the excitation of a single 3s core electron or more than one valence electron of the Cl- ion were found to be insignificant in the energy range studied.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevA.69.022711
DOI:
10.1103/PhysRevA.69.022711
PACS:
32.80.Gc

*Present address: National Institute of Standards and Technology, Gaithersburg, MD 20809, USA.

†Present address: ITAMP, Harvard Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA.

 
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