Inner-shell excitation of PF3, PCl3, PCl2CF3, OPF3 and SPF3 Part I. Spectroscopy

Total ion yield spectra of PF3, PCl3, PCl2CF3, OPF3 and SPF3 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 PF3 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 PF3 is particularly notable, analogous P 2p excited states with large singlet–triplet splittings are calculated in PCl3, PCl2CF3, OPF3 and SPF3. Aspects of partial ion yield measurements (particularly the PF3+ yield of PF3 and the SPF3+ yield of SPF3) 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.