Coster–Kronig decay of the 2s hole state in HCl observed by sub-natural linewidth Auger electron spectroscopy

Abstract

Threshold photoelectron–Auger electron coincidence spectroscopy has been applied to the Coster–Kronig transitions from the Cl 2s core-hole state of HCl. The use of coincidence spectroscopy reveals Auger lines associated with the Cl 2s core-hole state in the sub-natural linewidth regime. The coincidence Auger spectrum reveals two band structures corresponding to the formation of HCl 2+[(Cl 2p) −1 (V) −1] doubly ionized states via Coster–Kronig transitions, which are only weakly observed in the normal Auger spectrum. These structures are tentatively assigned to HCl 2+[(Cl 2p) −1 (V) −1] doubly ionized states with the 2 π or 5 σ valence (V) holes.