Semiclassical interferences and catastrophes in the ionization of Rydberg atoms by half-cycle pulses

A multidimensional semiclassical description of excitation of a Rydberg electron by half-cycle pulses is developed and applied to the study of energy- and angle-resolved ionization spectra. Characteristic phenomena. observable in these spectra such as interference oscillations and semiclassical glory and rainbow scattering are discussed and related to the underlying classical dynamics of the Rydherg electron. Modifications to the predictions of the impulse approximation are examined that arise due to finite pulse durations. [S1050-2947(99)50205-9].