SEMICLASSICAL FORMULA FOR OSCILLATOR-STRENGTHS IN ATOMIC SPECTRA

A simple semiclassical formula is given for the oscillator strengths o f high Rydberg states of a hydrogen atom in an electric field. The osc illator strength of a state is; proportional to the square of the func tion representing the quantum angular distribution of outgoing waves, evaluated at the classical angle of ejection from the atom that sends the electron into a semiclassically quantized eigentrajectory. The for mula gives an interpretation of the envelopes of Stark manifolds in ph otoabsorption spectra; it is in good agreement with quantum calculatio ns. The formula may also be used for other integrable or near-integrab le systems.