Theory and computation of the profile of the free - free transition probability between autoionizing (resonant) states

Abstract

We have derived the general expression for the energy-dependent cross section of the transition between two resonant states in the continuous spectrum of atoms and molecules, under the physically meaningful conditions of broadband excitation. The profile is expressed in terms of a symmetric, an asymmetric and a background component, and is cast in a form containing as limiting cases the discrete - discrete Lorentzian profile and the discrete - resonance Beutler - Fano profile. The theory has been implemented numerically by ab initio methods on the transition , for tunable radiation around 3.4 eV.