Electron localization involving doubly excited states in broadband extreme ultraviolet ionization of H2

Dissociative single ionization of H2 induced by extreme ultraviolet photons from an attosecond pulse train has been studied in a kinematically complete experiment. Depending on the electron kinetic energy and the alignment of the molecule with respect to the laser polarization axis, we observe pronounced asymmetries in the relative emission directions of the photoelectron and the H+ ion. The energy-dependent asymmetry pattern is explained by a semiclassical model and further validated by fully quantum mechanical calculations, both in very good agreement with the experimentA. G.-C., A. P., and F. M. acknowledge allocation of computer time by CCC-UAM and BSC Mare Nostrum and financial support from the Advanced Grant of the European Research Council XCHEM 290853, the European grants MC-RG ATTOTREND and ITN CORINF, the European COST Actions CM0702 (CUSPFEL) and CM1204 (XLIC), the MICINN projects No. FIS2010-15127 and No. CSD 2007-00010, and the ERA-Chemistry project No. PIM2010EEC-0075