Semiclassical Theory of Satellite Bands Produced in the Spectra of Alkali Metals by Interaction with Foreign Gases

A 6–12 potential is used to describe the interaction of an alkali atom in any state with a foreign gas molecule or atom. The hydrogenlike nature of the alkali combined with knowledge of the polarizability of the foreign gas atom allows an explicit semiclassical expression for the force constants to be given. This potential is used to relate the equilibrium separation of an alkali atom–noble gas collision pair to the position of the red satellite band produced. Within a series of levels of the same $l$ and $j$ , this separation is seen to vary linearly with the square of the effective principal quantum number. This permits an expression to be written for the line–band separation. As a check, positions of the bands are calculated. The results are in good agreement with previously reported experimental values.