Double core-hole electron spectroscopy for open-shell molecules: theoretical perspective

TL;DR

This paper provides a theoretical analysis of double core-hole states in open-shell molecules, exploring their energies and the potential of X-ray two-photon photoelectron spectroscopy to measure these states, with implications for chemical environment effects.

Contribution

It offers the first detailed theoretical investigation of DCH states in open-shell molecules and evaluates the feasibility of DCH spectroscopy using XTPPS.

Findings

DCH states' energies were calculated using CASSCF.

XTPPS can measure core-hole ionization potentials.

Chemical environment influences DCH states at different atomic sites.

Abstract

We have theoretically investigated the double core-hole (DCH) states of the open-shell molecules and examined the possibility of DCH spectroscopy by means of X-ray two-photon photoelectron spectroscopy (XTPPS). Energies of many DCH states were obtained by the CASSCF calculations and the generalized intra- and interatomic relaxation energies were evaluated. We show that XTPPS can extract these quantities by the measurement of single and double core-hole ionization potentials. We discuss the influence of chemical environment on the DCH states with two holes at the same atomic site and at two different atomic sites.