On the ionization energy of CF3SF5 in the valence region measured by angle-resolved photoelectron spectroscopy

Ionization energies for valence electrons of CF3SF5 were measured in the 12-35 eV region by means of angle-resolved photoelectron spectroscopy. The observed ionization energies were basically consistent with previous ones measured by threshold photoelectron and HeI photoelectron spectroscopy, and the ionization levels at 22.60, 26.92 and 27.86 eV were newly observed. Asymmetry parameter derived at hν = 684.7 eV was a constant of β = 1.02 ± 0.04 in the ionization energy lower than 20 eV, suggesting that lone pair electron of F atom is probably released through 2p → ɛd like electron emission. Characters of the 22 valence bands were elucidated with the help of ab initio calculations and of the nature of valence orbitals for CF4 and SF6.