A comparison of valence level photoelectron cross sections for SF 6, SeF 6 and “F 6” from 21 eV to 100 eV photon energy

Abstract

High resolution photoelectron spectra of SF 6 and SeF 6 have been obtained in the 21 to 100 eV photon energy range using synchrotron radiation. All valence levels as well as the lower lying F2s, and in the case of Se, 3 d levels were observed. Resulting experimental branching ratios and partial cross sections were then compared with those from MS-Xα calculations. This comparison provided the following valence level ordering for SF 6: 1 t 1g < (5 t 1u, 1 t 2u) < 3 e g < 1 t 2g < 4 t 1u < 5 a 1g. In addition, the existing body of knowledge on molecular shape resonances is increased through the detailed recording of cross section variations at higher kinetic energies, and through extension to a 3rd row atomic centre in SeF 6. The striking similarity of structure in both the experimental and theoretical partial cross sections of these two compounds confirms the existence of resonance channels acting upon photoionized valence electrons in both compounds and suggests that valence levels of g symmetry can resonate through t 1u channels. The degree of structure beyond the near threshold region led to a theoretical study of “F 6” in an octahedral environment in order to differentiate scattering from the F 6 cage from a molecular potential effect. The “F 6” calculations showed remarkable similarities to both the SF 6 and SeF 6 calculations; and along with simple calculations strongly indicate that the high KE features on both valence, S2 p and S1 s core levels (and part of the low KE features) are due to atomic scattering from the F atoms.