The contribution of incoherent photoelectron scattering off neighbouring atoms to the above-threshold ionization and detachment spectra

The role of incoherent scattering in above-threshold ionization (ATI) of atoms and above-threshold detachment of negative ions is investigated. We assume that the ionized (detached) electron may scatter on a target other than its parent ion (atom). We call such a process incoherent in order to distinguish it from the coherent rescattering of an electron on its parent ion (atom). The rescattering process is known to be responsible for high-order ATI (HATI). We show that the contribution to the ionization rate of ATI with a subsequent incoherent scattering can be higher than that of the rescattering-induced HATI if the density of atomic targets is high enough. The spectra of ATI with incoherent scattering have a cutoff-like behaviour, similar to that of ATI and HATI. Our numerical results show that the cutoff energy of the ATI with incoherent scattering is higher than that of the rescattering-induced HATI. These results are supported by classical analysis.