Hamburg 2009 – scientific programme
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A: Fachverband Atomphysik
A 28: Precision Spectroscopy of Atoms and Ions IV, Interaction with VUV and X-Ray Light III
A 28.4: Talk
Thursday, March 5, 2009, 14:45–15:00, VMP 6 HS-E
Photoionization Processes in H3O+ — •Brandon Jordon-Thaden1, Henrik Pedersen2, Simon Altevogt1, Oded Heber3, Lutz Lammich2, Michael Rappaport3, Dirk Schwalm1, Joachim Ullrich1, Daniel Zajfman3, Rolf Treusch4, Natalia Guerassimova4, Michael Martins5, and Andreas Wolf1 — 1Max-Planck-Institut für Kernphysik, D-69117 Heidelberg, Germany — 2Department of Physics and Astronomy, University of Aarhus, Aarhus, DK-8000 Aarhus C, Denmark — 3Department of Particle Physics, Weizmann Institute of Science, Rehovot, 76100, Israel — 4HASYLAB at DESY, D-22607 Hamburg, Germany — 5Institut für Experimentalphysik, Universtität Hamburg, D-22671 Hamburg, Germany
The fragmentation of the hydronium ion H3O+ after photoionization by high energy radiation plays a significant role in the chemistry in interstellar environments. In measurements performed at the Free-ELectron LASer in Hamburg (FLASH), the photoionization and subsequent dissociation of fast H3O+ ions with VUV photons in a cross-beam setup was measured where the photodissociating fragments were position and time analyzed by two detectors arranged in a serial geometry. An analysis of the coincidence and fragmentation patterns between the measured events yields the branching ratios between the multitude of possible channels with absolute cross-sections. Furthermore the kinetic energy release distribution for the two-body channels returns detailed information about the H3O2+ states after inner-valence ionization and the atomic and molecular photofragment states.