Ionization by short uv laser pulses: Secondary above-threshold-ionization peaks of the electron spectrum investigated through a modified Coulomb-Volkov approach

Abstract

Coulomb-Volkov approach was applied for investigating the interaction between an atom and a short laser pulse in case where both photon energies were smaller than the ionization potential. The secondary peaks show up in the above-threshold ionization (ATI) spectrum, as indicated by a full numerical solution of the time-dependent Schrödinger equation for a hydrogen atom initially in its ground state. A full numerical electron spectrum for smaller photon energies was obtained by introducing a coupling to intermediate bound states into the applied approach. The secondary peaks for the excitation of transient bound states followed by multiphoton absorption were easily traced with the help of the approach.