ac Stark effect in multiphoton ionization

Abstract

Multiphoton ionization of atomic sodium has been studied experimentally for near resonance between the radiation field and several bound-bound transitions of the atom. It has been found that the atom-field interaction must be treated in a highly nonlinear way to describe successfully the observations, even when the absolute spectral power densities are relatively modest. Rabi frequencies as high as 10 GHz are found to be directly observable with simple flashlamp-pumped tunable dye lasers.