Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 13: Photoionisation I (joint session A and MO)
A 13.12: Vortrag
Donnerstag, 5. April 2001, 18:30–18:45, H1012
Photoionization of Ca+ ions by synchrotron radiation — •S. Schippers1, A. Müller1, A. Covington2, A. Aguilar2, G. Hinojo sa2, R.A. Phaneuf2, M. Sant’Anna3, A.S. Schlachter3, J. D. Bozek3, and C. Cisneros4 — 1Institut für Kernphysik, Universität Giessen, Germany — 2University of Nevada, Reno, USA — 3Advanced Light Source, Lawrence Berkeley Laboratory, California, USA — 4Centro de Ciencas Fisicas, UNAM, Cuernavaca, Mexico
Multiply excited states play an important role in
electron-ion and
photon-ion interactions. Ionization cross sections are often dominated by
indirect processes
forming intermediate autoionizing states, which then decay into the
different final channels
observed in various types of experiments. As a consequence of time-reversal
identical
intermediate states are involved in both processes. Measurements of
photoionization of
Aq+ ions and photorecombination of A(q+1)+ ions complement one
another, revealing
information about identical intermediate states and their decay properties.
As the first of
a series of measurements on ions of the potassium isoelectronic sequence,
photoionization of
Ca+ was investigated in the energy range from about 20 to 50 eV. One
objective was to
determine the energy and line width of the rapidly decaying 3p5
3d2 2F state
which may be populated by the photoionization of 3p6 3d metastable
Ca+. The measured
energy of 29.4 eV differs by 0.6 eV from a recent theoretical prediction
[1]. The observed
line strength together with this calculation and previous absolute
measurements [2] suggests
a metastable fraction of 2−3 % of the parent ion beam. Furthermore we
find evidence of
interference between direct 3p inner-shell photoionization and resonances
due to double
core-excitation.
[1] J. E. Hansen and P. Quinet, J. Elec. Spectrosc. Rel. Phenom. 79, 307 (1996)
[2] I. C. Lyon, B. Peart, K. Dolder, and J.B. West, J. Phys. B 20, 1471 (1987)