Stuttgart 2012 – wissenschaftliches Programm
MO 22.6: Vortrag
Freitag, 16. März 2012, 11:45–12:00, V38.02
Molecular fragmentation and charge redistribution in XeF2 after K-shell photoionization — Robert W. Dunford1, Stephen H. Southworth1, Dipanwita Ray1, Elliot P. Kanter1, Bertold Kraessig1, Linda Young1, Dohn A. Arms1, Eric M. Dufresne1, Donald A. Walko1, •Oriol Vendrell2, Sang-Kil Son2, and Robin Santra2,3 — 1Argonne National Laboratory, Lemont, IL 60439, USA — 2Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany — 3Department of Physics, University of Hamburg, 20355 Hamburg, Germany
The photoionization of an inner-shell electron in a heavy atom by synchrotron radiation sets off a cascade of x-ray and Auger transitions as the atom relaxes and reaches its final charge state. If the heavy atom is embedded in a molecule, the decay is accompanied by charge redistribution and molecular fragmentation processes.
In this work, we investigate the effect of Xe K-shell hole in XeF2 and compare it to the isolated atomic case, Xe. The average total charge produced for Xe is +8, whereas it is +9 for XeF2. Such similarity suggests a model in which the cascade proceeds at the atomic level followed by charge redistribution and Coulomb explosion. Simulations of the decay cascade of Xe, however, indicate that the cascade lasts for about 100 fs, in which case nuclear motion may play a role. Moreover, energetic considerations based on an independent ion model suggest that it is unlikely that the total charge in XeF2 is initially produced entirely on Xe. Therefore, a more complex mechanism involving molecular effects is probably at play.