Relating the4sσ−1inner-valence photoelectron spectrum of HBr with the Br3d−15lλresonant Auger spectra: An approach to the assignments

Abstract

The high resolution Br $4s{\ensuremath{\sigma}}^{\ensuremath{-}1}$ photoelectron spectrum of HBr is presented together with the resonant Auger spectra resulting from excitations from the $3d$ core levels to the low-$n$ Rydberg orbitals $5s\ensuremath{\sigma},$ $5p\ensuremath{\sigma},$ and $5p\ensuremath{\pi}.$ The very complex spectra can be broadly assigned using two observations. First, the energy splittings of the $4p{\ensuremath{\pi}}^{\ensuremath{-}2}5s$ and $4p{\ensuremath{\pi}}^{\ensuremath{-}2}5p$ states are very similar to the splittings of the $4p{\ensuremath{\pi}}^{\ensuremath{-}2}{(}^{1}{\ensuremath{\Sigma}}^{+}{,}^{1}\ensuremath{\Delta},\mathrm{and}{}^{3}{\ensuremath{\Sigma}}^{\ensuremath{-}})$ final states seen previously in the normal Auger spectra. Second, the ${}^{2}{\ensuremath{\Sigma}}^{+}$ states, which are the dominant correlation satellites in the complex $4s{\ensuremath{\sigma}}^{\ensuremath{-}1}$ photoelectron spectrum, are often enhanced in the $5s\ensuremath{\sigma}$ resonance Auger spectra. Electron correlation and spin-orbit interaction in the final states are important to understand all of these spectra. Unlike the normal Auger spectra, vibrational excitations play only a minor role in these spectra, showing that the $5s$ and $5p$ Rydberg orbitals have some bonding character.