Laser assisted electron dynamics

Abstract

We apply the convergent close-coupling (CCC) formalism to analyse the processes of laser assisted electron impact ionisation of He, and the attosecond time delay in the photodetachment of the H^{-} ion and the photoionisation of He. Such time dependent atomic collision processes are of considerable interest as experimental measurements on the relevant timescale (attoseconds 10^{-18} s) are now possible utilising ultrafast and intense laser pulses. These processes in particular are furthermore of interest as they are strongly influenced by many-electron correlations. In such cases their theoretical description requires a more comprehensive treatment than that offered by first order perturbation theory. We apply such a treatment through the use of the CCC formalism which involves the complete numeric solution of the integral Lippmann-Schwinger equations pertaining to a particular scattering event. For laser assisted electron impact ionisation of He such a treatment is of a considerably greater accuracy than the majority of previous theoretical descriptions applied to this problem which treat the field-free scattering event within the first Born approximation. For the photodetachment of H^{-} and photoionisation of He, the CCC approach allows for accurate calculation of the attosecond time delay and comparison with the companion processes of photoelectron scattering on H and He^{+}, respectively.