Experimental and theoretical study of the double ionization of the sulphurhexafluoride molecule to singlet and triplet electronic states of its dication

The results of a combined experimental and theoretical study of the double ionization of sulphur hexafluoride are reported. Double-charge-transfer (DC T) spectroscopy was used in the experimental investigation. Double-electron -capture (DEC) reactions, on which DCT spectroscopy is based, are known to be subject to spin conservation. Consequently, double-ionization energies t o singlet and triplet electronic states of SF62+ were measured by using Hand F+ projectile ions, respectively. In the theoretical investigation, ADC (2) Green's function calculations indicated a high density of singlet and t riplet electronic states for SF62+. It was found, however, that groups of s tates could be identified that were well separated from adjacent groups. Th e average double-ionization energies (DIEs) for these groups are in good ag reement with those measured. The combined experimental and theoretical appr oach has thus provided a considerably improved understanding of the double ionization of the SF, molecule. (Int J Mass Spectrom 185/186/187 (1999) 651 -662) (C) 1999 Elsevier Science B.V.