(LS) versus (jj) coupling in P 2p inner-shell excited states of PF3

The P 2p total and parent ion yield spectra of PF3 have been measured and interpreted with ab initio SCF-CI calculations. The PF+3 yield has only one line at 136.5 eV, without a spin-orbit partner. The ab initio calculations attribute it to the (e−1, e)1A1 state. They predict the (e−1, e)3A1-(e−1, e)1A1 state separation is 2.4 eV, much greater than for other P 2p states (0.05–0.5 eV), and much larger than the P 2p−1 spin-orbit splitting (0.9 eV). We conclude the 136.5 eV state is the (LS) coupled (e−1, e)1A1 state, and the normally dominant P 2p−1 spin-orbit (jj) splitting can be ignored. The importance of treating core-valence exchange as well as spin-orbit interactions is discussed.