Observation of Vibrational Dynamics of Orientated Rydberg-Atom-Ion Molecules.

Vibrational dynamics in conventional molecules usually takes place on a timescale of picoseconds or shorter. A striking exception are ultralong-range Rydberg molecules, for which dynamics is dramatically slowed down as a consequence of the huge bond length of up to several micrometers. Here, we report on the direct observation of vibrational dynamics of a recently observed Rydberg-atom-ion molecule.

Observation of a molecular bond between ions and Rydberg atoms.

Atoms with a highly excited electron, called Rydberg atoms, can form unusual types of molecular bonds. The bonds differ from the well-known ionic and covalent bonds not only by their binding mechanisms, but also by their bond lengths ranging up to several micrometres. Here we observe a new type of molecular ion based on the interaction between the ionic charge and a flipping-induced dipole of a Rydberg atom with a bond length of several micrometres.