Stuttgart 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
A: Fachverband Atomphysik
A 27: Poster: Photoionization
A 27.3: Poster
Mittwoch, 14. März 2012, 16:30–19:00, Poster.V
Quasi free mechanism in single photon double ionization of Helium — •Markus Schöffler1,2, Till Jahnke1, Markus Waitz1, Florian Trinter1, Ute Lenz1, Christian Stuck1,2, Mathew Jones3, Ali Belkacem2, Lew Cocke4, Allen Landers3, Horst Schmidt-Böcking1, Thorsten Weber2, and Reinhard Dörner1 — 1Institut für Kernphysik, J. K. Goethe-Universität Frankfurt am Main, 60438 Frankfurt — 2Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA — 3Auburn University, Auburn, AL, 36849, USA — 4Kansas State University, Manhattan, KS, 66506, USA
Double ionization of Helium by a single photon is widely believed to proceed through two mechanisms: knock-off (TS1) or shake-off, with the last one dominating at high photon energies. A new mechanism, termed "Quasi Free Mechanism" (QFM) was predicted 35 years ago by Amusia and coworkers, but escaped experimental observation till today. Here we provide the first proof of this mechanism using 800 eV photons from the Advanced Light Source. Fragments (electrons and ions) were measured in coincidence using momentum spectroscopy (COLTRIMS). He2+ ions with zero momentum were found - the fingerprint for the QFM.