Angle-resolved photoion yield and resonant Auger spectroscopy for the doubly excited Rydberg states above the C1sthreshold of CO

Abstract

Doubly excited core-hole states of carbon monoxide in the photon energy region of $300--305\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$, i.e., directly above the C $1s$ ionization threshold, have been studied using both angle-resolved ion-yield and high-resolution resonant Auger spectroscopies. The leading configurations of the most prominent doubly excited Rydberg states are assigned by careful analysis of the ion-yield spectra and the final-state spectra to C $1{s}^{\ensuremath{-}1}$ $(5{\ensuremath{\sigma}}^{\ensuremath{-}1}2{\ensuremath{\pi}}^{1}S=1)$ $3s\ensuremath{\sigma}$ $({v}^{\ensuremath{'}}=0,1,2)$, C $1{s}^{\ensuremath{-}1}$ $(5{\ensuremath{\sigma}}^{\ensuremath{-}1}2{\ensuremath{\pi}}^{1}S=0)$ $3s\ensuremath{\sigma}$ $({v}^{\ensuremath{'}}=0,1,2)$, and C $1{s}^{\ensuremath{-}1}$ $(5{\ensuremath{\sigma}}^{\ensuremath{-}1}2{\ensuremath{\pi}}^{1}S=1)$ $4s\ensuremath{\sigma}$ $({v}^{\ensuremath{'}}=0,1)$, which can only be populated via a conjugate shake-up process. Analysis of the resonant Auger spectra provides an assignment of several two-hole--one-electron $(2h\text{\ensuremath{-}}1e)$ final states.