In the scope of this thesis, the long-range interaction between Rydberg atoms and ions is studied. Depending on the prepared Rydberg state, the two particles either collide or form a novel type of molecular bond. This type of molecular bond has been predicted only recently and is observed for the first time in a cold rubidium gas as part of this thesis. The binding mechanism is based on the dipole moment of the Rydberg atom, which is induced by the ion. The dipole changes its orientation around an equilibrium distance and therefore binds the two partners together. The binding length is extremely large for a diatomic molecule and on the order of 2 μm to 4 μm for the studied vibrational states. By photoassociation spectroscopy, a dozen vibrational states are identified and their energy spacings fit excellent with theoretical calculations. An ion microscope allows for the spatially and temporally resolved observation of the Rydberg-atom–ion pairs. In situ images of the molecule reveal, that the alignment of the molecule can be controlled by the polarization of the excitation laser. The presented results on classical Rydberg-atom–ion collisions demonstrate the influence of highly polarizable Rydberg states on the dynamics and illustrate the potential of the microscope for future studies in the ultracold quantum regime. By imaging a periodic structure with a period of 240nm, the employed ion microscope is determined to possess a resolution below 200nm. The results render it excellently suited to study interactions and transport phenomena in bulk systems of Rydberg atoms, ultracold atoms or ion-atom hybrid systems.weiterlesen