Semiempirical potentials for alkali-noble gas interactions

A semiempirical calculation of alkali-noble gas interatomic potentials applicable to excited states of the alkali at internuclear separations and energies important for the interpretation of optical line broadening experiments is presented. The assignment of a single adjustable parameter is based on a comparison with scattering cross-section measurements of ground state potentials. Evidence that the repulsive interaction scales as the collision cross section of the noble gas atoms for low energy electrons is presented, and simple formulas are developed to predict potentials for all alkali-noble gas combinations as a function of noble gas dipole and quadrupole polarizabilities and alkali unperturbed energy. Additional comparisons are made with data from satellite bands in Cs–Xe and Cs–Kr spectra, and the impact broadening and shift of alkali spectral lines at low foreign gas pressure is calculated from the predicted potentials and compared with available experimental data.