Dynamic processes in Rydberg-atom-ion systems

Abstract

In this thesis an ion microscope is used to study ion-Rydberg interactions in a cold quantum gas of rubidium atoms in real space. This allowed the observation of charged ultralong-range Rydberg molecules consisting of an ion and a Rydberg atom. The molecule is based on a charge-induced flipping dipole bond and shows a bond length of several micrometers. Due to the versatile nature of the ion microscope, the molecules could not only be studied by means of conventional spectroscopy and mass spectrometry, but could also be directly observed in real space images. Thus, the spatial alignment, caused by the laser polarization during the photoassociation, could be detected in situ. Furthermore, the response of the molecule to an external electric field was investigated, opening up the possibility to not only associate the molecule in an aligned, but also an orientated way. Owing to the exceptionally long bond length of these molecules, dynamical processes are slowed down drastically, which provides the possibility to observe the molecular vibrational motion directly. Finally, the onset of collision dynamics between an ion and a Rydberg atom in a purely attractive potential was analyzed. At sufficiently small distances, the charge-induced Stark shift leads to a large number of avoided crossings between an atomic Rydberg state and the adjacent hydrogenic manifold. These crossings open up additional fast collision channels whose population can be described by a Landau-Zener hopping process. For a certain energy regime this results in a counter-intuitive behavior, as initially slow particles predominantly occupy steep collision channels and therefore experience a drastic speed up in the collisional process.