Electronic state-lifetime interference in resonant Auger spectra: a tool to disentangle overlapping core-excited states

Abstract

We have measured resonant-Auger decay following Cl 1s⁻¹ excitations in HCl and CH₃Cl molecules, and extracted the pseudo-cross sections of different Cl 2p⁻² final states. These cross sections show clear evidence of shake processes as well as contributions of electronic state-lifetime interference (ELI). To describe the spectra we developed a fit approach that takes into account ELI contributions and ultrafast nuclear dynamics in dissociative core-excited states. Using this approach we utilized the ELI contributions to obtain the intensity ratios of the overlapping states Cl 1s⁻¹4pπ/1s⁻¹4pσ in HCl and Cl 1s⁻¹4pe/1s⁻¹4pa₁ in CH₃Cl. The experimental value for HCl is compared with theoretical results showing satisfactory agreement.