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Abstract

During the course of this thesis, two optical interferometers for pump-probe experiments with strong laser fields were built up and put into operation. Both employed two laser pulses of different wavelength to investigate the ionization dynamics of noble gas atoms. A reaction microscope allowed to detect the full three-dimensional momentum vectors of the charged particles after interaction with the laser pulses. The main goal of the experiments was to study the existence of time delays in the tunnel ionization of argon and krypton. It was possible to imprint information on the timing of the tunnel ionization onto the momenta of the ions and electrons at the detector by controlling the shape of the electric field of the laser with adjustments to the time delay between pump and probe pulses. A comparison between the ionization dynamics of argon and krypton revealed only small differences which could be partly reproduced by a semi-classical model without incorporating a tunneling time. This lead to the conclusion that either the time delays in tunnel ionization are very small (on the order of a few 10 as) or that they differ only very little between argon and krypton.