%0 Generic
%A Laux, Martin
%D 2017
%F heidok:23688
%R 10.11588/heidok.00023688
%T Photoionization in strong laser fields:  from atoms to complex molecules
%U https://archiv.ub.uni-heidelberg.de/volltextserver/23688/
%X In this  thesis, the results of the strong-field photoionization of various gas targets, particularly  of methane are presented. The photoionization was performed by focusing an ultrashort  two-color laser pulse into the supersonic gas jet of a Reaction Microscope. The capability  of the Reaction Microscope of simultaneous detection and identification of all charged  ionization products enables the channel- and fragment-specific analysis of the ionization  process. The tunable relative phase between both components of the two-color field is  an additional control parameter for the experiment. The discrepancy in the yield of lowenergy  photoelectrons for methane ionization channels with a coincident molecular ion  on the one hand and a coincident atomic ion on the other hand resembles similar results  from experiments in molecular hydrogen, which could be explained by autoionization  and simultaneous vibrational relaxation of a molecular Rydberg state. Despite the lack of  reference data for Rydberg states of methane with excitations higher than n = 6, it was  possible to estimate their energies and for one ionization channel, it could be demonstrated  that electrons released by autoionization of Rydberg states between n = 9 and n = 12 are  the origin of the enhanced low-energy electron yield.