Theoretical study of the Rydberg excited electronic states of Ar+2

Abstract

The first Rydberg states of the Ar+2 molecular ion dissociating into Ar+(3p5,2P) +Ar*(3p54s,3,1P) are calculated using multireference configuration interaction and effective core pseudopotentials. At long internuclear distance, their electronic structure is shown to be determined by resonance interaction and the magnitude of the Rydberg electron-transfer integral, inducing long-distance wells with De in the range 0.6–0.8 eV around Re≂9.0a0. In the short distance range, the electronic structure can be understood as resulting from an ionic Ar++ core with an outer Rydberg electron, and bound or quasibound Rydberg states are obtained around Re∼4a0. The fluorescence spectra of those states are simulated and the possible intervention of the Ar+2 system in the third continuum spectrum is considered.