Core–core and core–valence double ionisation

Abstract

Abstract Basic concepts of inner shell double ionisation phenomena are discussed and examples are presented. An empirical model to calculate single-site K-shell double ionisation energies is proposed and the enhanced chemical shifts in double L-shell ionisation are illustrated. Core–valence double ionisation spectra are shown to closely resemble photoelectron spectra from single ionisation in many cases. Core–valence double ionisation spectra of NH3, CO, CO2, OCS, CS2, CF4, Si(CH3)4, benzene, and C60 are presented with analysis. In the context of core ionisation it is customary to use the very economical ‘KLM’ notation, which is universally used in Auger spectroscopy, as well as the chemists’ familiar 1s, 2s, 2p, and so on. This chapter uses the KLM notation sparingly where its brevity is an advantage, so a short table list of equivalents is also included here.