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Abstract

In this thesis multiphoton ionization of molecular hydrogen is investigated by using 50 fs laser pulses with 400 nm central wavelength and a Cold Target Recoil Ion Momentum Spectrometer (COLTRIMS), known as Reaction Microscope (ReMi). It was found that singly excited Rydberg states play a dominant role in the bound ionization process. In order to examine the importance of these Rydberg states for the dissociative ionization, the electron nuclear correlation and electron emission asymmetry was studied experimentally and theoretically. The kinetic energy distribution of the ions is simulated by numerically solving the time-dependent Schrödinger equation, whereas the electron localization asymmetry is modeled with a semiclassical theory. The presented findings indicate that dissociation via the H⁺₂ 1sσ_g state is much less pronounced than commonly believed. Singly-excited Rydberg states are found to play the most important role in multiphoton bound and dissociative ionization of molecular hydrogen with 400 nm photons. The second part of the thesis reports about a pump-probe measurement using a pulse shaper setup in 4f geometry. To our knowledge this is the first report about combining a pulse shaper with a ReMi. The experimental data is compared to a former pump-probe measurement that uses a Mach-Zehnder interferometer to confirm the correct operation of the pulse shaper.