Theory of Auger decay by laser-dressed atoms

Abstract

We devise an ab initio formalism for the quantum dynamics of Auger decay by laser-dressed atoms which are inner-shell ionized by extreme ultraviolet (xuv) light. The optical dressing laser is assumed to be sufficiently weak such that ground-state electrons are neither excited nor ionized by it. However, the laser has a strong effect on continuum electrons which we describe in strong-field approximation with Volkov waves. The xuv light pulse has a low peak intensity and its interaction with the atom is treated as a one-photon process. The quantum dynamics of the inner-shell hole creation with subsequent Auger decay is given by equations of motion (EOMs). For this paper, the EOMs are simplified in terms of an essential-states model which averages over magnetic subshells and is solved analytically. We apply our theory to the ${M}_{4,5}{N}_{1}{N}_{2,3}$ Auger decay of a $3d$ hole in a krypton atom. The orbitals are approximated by scaled hydrogenic wave functions. A single attosecond pulse produces $3d$ vacancies which Auger decay in the presence of an 800 nm laser with an intensity of ${10}^{13}\text{ }\text{W}\text{ }{\text{cm}}^{\ensuremath{-}2}$. We compute the Auger electron spectrum and assess the convergence of the various quantities involved.