Molecular fragmentation and charge redistribution in XeF₂ after K-shell photoionization

Robert W. Dunford, Stephen H. Southworth, Dipanwita Ray, Elliot P. Kanter, Bertold Kraessig, Linda Young, Dohn A. Arms, Eric M. Dufresne, Donald A. Walko, Oriol Vendrell, Sang-Kil Son, and Robin Santra

[BibTeX]http://www.dpg-verhandlungen.de/year/2012/conference/stuttgart/part/mo/session/22/contribution/6

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.