Shape-resonance-induced long-range molecular Rydberg states

When an excited atomic electron interacts with a neutral perturbing atom or molecule that possesses a shape resonance, it generates a characteristic class of Bom-Oppenheimer potential curves that rise with internuclear distance. We document this effect, and predict the existence of a diverse class of stable, strongly bound atom-atom and atom-molecule states that result from this phenomenon. For the specific case in which Rb is the perturbing atom, we show that such states should be observable in the spectroscopy of an ultracold gas or condensate.