Ultrafast Spectroscopy of Atomic and Molecular Quantum Dynamics

An all-pervading feature of the work presented in this thesis is the study of ultrafast dynamics, both theoretically and experimentally, in terms of time-dependent wave functions (wave packets). We have experimentally, by pump-probe fluorescence spectroscopy, examined spin-orbit interactions, by time-tracing molecular wave packets on excited states of diatomic rubidium, and the main channels causing the fast predissociation from one of those states is revealed. The time evolution of wave packets and their extension in space, in addition to varying transition dipole moment is of specific interest in the semiclassically derived expressions for the total ion signal, in the context of pump-probe ionization spectroscopy on diatomic molecules. We have experimentally, by pump-probe fluorescence spectroscopy, addressed a previously derived theoretical prediction about level interactions between atomic levels with all angular momentum quantum numbers equal but different principal quantum numbers. Hence, the ultrafast progression of atomic radial wave packets are disclosed in terms of quantum beat frequencies and explained theoretically in the context of pump-probe fluorescence spectroscopy. Preliminary fluorescence up-conversion experiments are as well treated in this thesis with the aim to reveal further experimental knowledge on the previously derived theoretical prediction on the specific level interactions mentioned above