Rydberg states of calcium fluoride

Abstract

We derive the entire singly excited electronc level spectrum of a dipolar molecule (CaF) from atomic properties alone (the quantum defects of ${\mathrm{Cd}}^{+}$). In the approach presented here the motion of the lone electron is treated as a double scattering process involving the closed-shell ${\mathrm{Ca}}^{++}$ and ${\mathrm{F}}^{\mathrm{\ensuremath{-}}}$ centers with ${\mathrm{F}}^{\mathrm{\ensuremath{-}}}$ treated as a point charge. The energies of all known electronic states of CaF are well reproduced by the theory. Refinements of the model such as inclusion of the finite volume of ${\mathrm{F}}^{\mathrm{\ensuremath{-}}}$ or of polarization effects are deferred as are extensions of the model to account for spin-orbit and other fine structure effects.