From Positive to Negative Ions, Studies Based on Rydberg Spectroscopy

This thesis studies interactions of Rydberg atoms with neutral atoms and with single ions. While for the studies of Rydberg atom-neutral interaction the case of one, few, or even many atoms interacting with a single Rydberg electron is investigated, for the ion-Rydberg atom system mostly binary interaction is studied. Beyond that, the level structure of negative ions is explored in the context of ultralong-range Rydberg molecules. The experiments are carried out in a gas made of rubidium-87 atoms at ultracold temperatures, where the motion of atoms is usually frozen out on the time and length scale of such experiments.