Anisotropy of fragment ions from SF6 by photoexcitation between 23 and 210 eV

The anisotropy of the ionic photofragments produced from SF6 has been measured using synchrotron radiation in the range of 23–210 eV. Despite the highly symmetrical molecule a strong anisotropy is observed below ∼35 eV. The behavior of the asymmetry parameter involving all the fragment ions has been interpreted by simulation using partial oscillator strengths for the formation of individual species. Only SF5+ ions produced via superexcited states of valence type are assumed to have an anisotropic angular distribution. The observed decrease in the asymmetry parameter with increasing photon energy can be ascribed to the dominance of direct photoionization and the decrease in the branching ratio for SF5+ formation.