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Astron. Astrophys. 334, L26-L28 (1998)


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Letter to the Editor

Shake-up processes following K-shell photoionization in the Boron isoelectronic sequence

S. Stoica * , D. Petrini and F. Bely-Dubau

Observatoire de la Côte d'Azur, Department G. D. Cassini, BP 4229, F-06304 Nice Cedex 4, France (e-mail: petrini@obs-nice.fr)

Received 31 October 1997 / Accepted 31 March 1998

Abstract

The direct and conjugate shake-up cross sections for the 2p [FORMULA] 3p, 3s and 2s [FORMULA] 2p, 3s transitions are calculated for CII, NIII, OIV, FV and NeVI in a close-coupling approximation using the R-matrix method. We find that the total shake-up cross section relative to that for single photoionization decreases with increasing Z. The decrease is about a factor 10 when going from BI to NeVI. When the full shake-up regime is reached, i.e. for about twice the 1s threshold energy, the cross section ratio ranges from about 15% for CII to about 3.5% for NeVI, of the single 1s inner-shell photoionization cross section. The 2s [FORMULA] 3s transition gives the dominant contribution for all ions. The 2p [FORMULA] 3p and 2s [FORMULA] 2p excitation contributions are broadly comparable in this energy range, while the 2p [FORMULA] 3s transition is negligible. Our results suggest that the importance of shake off excitation is significant for low Z ions.

Key words: atomic physics: K – photoionization: shake-up process

Send offprint requests to: S. Stoica
* Permanent address: Department of Theoretical Physics, Institute of Physics and Nuclear Engineering, P.O. Box MG-6, 76 900-Bucharest, Romania (e-mail: stoica@theor1.ifa.ro)

© European Southern Observatory (ESO) 1998

Online publication: May 12, 1998

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