The multielectron character of the S 2p → 4e_g shape resonance in the SF₆ molecule studied via detection of soft X-ray emission and neutral high-Rydberg fragments

We have studied the nature of the S 2p → 4e_g shape resonance in the SF₆ molecule by performing two different experiments. Soft X-ray emission spectra measured at the 4e_g shape resonance reveal features that do not originate from the S 2p^-1 states. One of the features can be assigned to the 6a_1g → S 2p transition. The 6a_1g orbital, which is empty in the molecular ground state, can be populated either in core-valence double excitations or in S 2p shake-up transitions. Both these channels are considered. We have also studied the fragmentation of SF₆ molecule after the decay of the S 2p core-hole states by observing neutral fragments in high-Rydberg states, where an electron occupies an orbital with n ≥ 20 (n is the principal quantum number). Such neutral fragments become, in relative terms, more abundant at the S 2p → 4e_g shape resonance with respect to the S 2p → 2t_2g shape resonance, which is a pure one-electron phenomenon.