Excitation of weakly bound Rydberg electrons by half-cycle pulses

The interaction of a weakly bound Rydberg electron with an electromagnetic half-cycle pulse (HCP) is described with the help of a multidimensional sem iclassical treatment. This approach relates the quantum evolution of the el ectron to its underlying classical dynamics. The method is nonperturbative, and is valid for arbitrary spatial and temporal shapes of the applied HCP. On the basis of this approach, angle- and energy-resolved spectra resultin g from the ionization of Rydberg atoms by HCP's are analyzed. The different types of spectra obtainable in the sudden-impact approximation are charact erized in terms of the appearing semiclassical scattering phenomena. Typica l modifications of the spectra originating from finite-pulse effect are dis cussed. [S1050-2947(99)03108-X].