Multiphoton detachment with atom excitation: explicit three-step quantumtheory

Abstract

A quantitative theory of multiphoton detachment with excitation of the residualatom, A− + Nω → A* + e, isdeveloped. A fully quantum treatment explicitly casts the amplitude as a result ofrescattering (or a three-step process), where the above-threshold detachment (ATD)is followed by continuum electron propagation in the laser field and subsequentexcitation of the residual atom by laser-dressed electron impact. The contributionsof all intermediate ATD channels add up coherently. All three stages of theprocess are described by simple expressions. The theoretical scheme is similar tothat employed previously for the calculation of high harmonic generation andhigh-channel ATD by an intensive laser field. To illustrate the general approach,H−detachment with excitation of the residual H atom into 2s and2p states is calculated for various numbers of absorbed photons,N. Theoscillations in the angle-differential rates are qualitatively similar to those alreadyknown for the conventional ATD process without atom excitation. The ratessummed over photoelectron emission angles exhibit non-monotonous dependenceon the number of absorbed photons and are also qualitatively similar to knownATD patterns.