Bound state evolution in atoms exposed to intense laser fields

This thesis describes a number of experiments which investigated bow bound states in atoms exposed to intense laser pulse evolved both during and after the laser pulse. Specifically, a variety of mutiphoton ionization measurements in Li have been analyzed using a simple Floquet model which is essentially a dressed-state representation of atomic levels in the presence of a strong laser field. The results of the analysis show that the adiabatic evolution of bound states during the laser pulse determined the outcome of the ionization process. A multiphoton ionization experiment in K was performed which explicitly demonstrated that the evolution of intermediate bound states can be either adiabatic or diabatic, with the end result of the ionization process being very different for the two cases. Finally, the time evolution of nonstationary wave packet states after the exciting laser pulse was studied in several different experiments using either a time-domain bound-state interferometric technique or a standard time-delayed photoionization technique. In all the experiments, the wave packet state consisted of coherently excited states in Ba atoms. The fact that Ba is a two-electron system introduced added complexity to the wave packet evolution as compared to the evolution of wave packet states excited in one-electron atoms. Analysis of the wave packet evolution in two-electron atoms may provide insight into possible approaches for coherent control of molecular processes.