Interaction between a Rydberg atom and neutral perturbers

Abstract
A simple combination of quantum defect theory with a nonperturbative Fermi-type analysis is shown to reliably determine a class of molecular Born-Oppenheimer potential curves. Applications to alkali-metal-atomrare-gas-atom dimers verify that their potential curves are determined to semiquantitative accuracy using two pieces of information: the alkali-atom quantum defects and the electronrare-gas scattering phase shifts.