Modelling laser ionisation

Abstract

The authors examine the detailed dynamics of an idealised photoionisation process by examining numerical solutions to a model of monochromatic photoionisation: a one-dimensional single bound-state square well. They find, as would occur when modelling photoionisation by a complex energy operator, exponential decay of the bound-state probability. They also observe oscillations in the bound-state probability at the driving frequency; these originate in oscillatory localised motion of the probability packet as would be expected for a classical particle driven by an oscillatory field. They further find, when excitation frequencies are slightly above threshold and the interaction is sufficiently intense, slowly modulated departures from exponential decay. These originate in the action of the dipole force over large distances.