Threshold shifts in strong radiation fields: The connection between dc and ac effects.

Abstract

We have studied near-threshold single-photon detachment of a model negative ion, in the presence of a second, intense radiation field. We find a simple, continuous connection between detachment in strong static fields (dc limit) and the increased energy needed to detach an electron into an intense optical field (ac limit). Below this shifted threshold energy, net detachment is suppressed because parent systems reabsorb electrons that have been temporarily emitted. This fragile emission-absorption process is easily upset, leading to leakage detachment below the shifted threshold.