title: Universal properties in ultracold ion-atom interactions.
abstract: We present some of the universal properties in ion-atom interaction derived from a newly formulated quantum-defect theory for the -1/r4 type of long-range interactions. For bound states, we present the universal bound spectrum, namely, the equivalent of the Rydberg formula, for ion-atom systems. For scattering, we introduce the concept of a universal resonance spectrum to give a systematic understanding of many resonances present in ion-atom scattering. The theory further provides a method for an accurate spectroscopic determination of the atomic polarizability. It also suggests the existence of atomlike molecules, in which multiple atoms orbit around a heavy ion.
authors.affiliation: Department of Physics and Astronomy, University of Toledo, Mailstop 111, Toledo, Ohio 43606, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Gao