Sulfur1score-level photoionization ofSF6

Photoelectron spectra have been taken between 2460 and 2600 eV photon energy across the discrete and continuum resonances in the vicinity of the sulfur K edge in gaseous ${\mathrm{SF}}_6$. Results at the below-threshold S 1s→6$t_{1u}$ resonance indicate that ‘‘highly excited’’ S 2p and S 2s satellites (with two core holes) are the primary autoionization final states of ${\mathrm{SF}}_6$ ${\mathrm{}}^{+}$. An observed asymmetric profile in the S(LVV) Auger angular distribution suggests interference effects in the alignment of these resonantly produced ${\mathrm{SF}}_6$ ${\mathrm{}}^{+}$ ions. Decay of the low-energy S 1s continuum resonances near 2507 eV photon energy into S 2p, S 2s, and/or valence photoemission channels indicates autoionizing character. These features are assigned as doubly excited states, leading to S 1s satellite thresholds observed here for the first time. At higher photon energies, between 2520 and 2570 eV, large oscillations in the S 1s cross section are reproduced well by multiple-scattering Xα calculations, but are not explained adequately by single-scattering plane-wave extended x-ray absorption fine structure effects. We speculate that improvements in the description of both the electron scattering process and the molecular potential are necessary to model the diffractive and nondiffractive (barrier interaction) effects in this energy region.