Inner-shell excitation of PF 3, PCl 3, PCl 2CF 3, OPF 3 and SPF 3: Part I. Spectroscopy

Abstract

Total ion yield spectra of PF 3, PCl 3, PCl 2CF 3, OPF 3 and SPF 3 were recorded in the region of P 2p, P 2s, S 2p, S 2s and halogen (Cl 2p, F 1s) excitation using synchrotron radiation. The P 2p spectra are interpreted with GSCF3 ab initio configuration interaction calculations optimized for core excitation studies. The experimental–theoretical comparison is based on both absolute intensities (oscillator strengths) and transition energies. The calculations indicate that several of the discrete states (e.g., that in PF 3 at 136.5 eV) are best described as LS-coupled states because the core–valence electron exchange is very large and thus the singlet–triplet splitting is larger than the spin–orbit splitting. While the state at 136.5 eV in PF 3 is particularly notable, analogous P 2p excited states with large singlet–triplet splittings are calculated in PCl 3, PCl 2CF 3, OPF 3 and SPF 3. Aspects of partial ion yield measurements (particularly the PF 3 + yield of PF 3 and the SPF 3 + yield of SPF 3) support this interpretation by revealing isolated single states without a corresponding partner at the spin–orbit splitting. The partial ion yields help clarify spectral interpretation by removing interference from overlap with adjacent states having the normal ( j, j)-coupled ion core character.