N. Kosugi ^{a}, R.G. Cavell^{b}, A.P. Hitchcock^{c}

**Abstract**

The P 2p total and parent ion yield spectra of PF_{3}
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
-', e)^{1 }A_{1} state. They predict the (e ^{- 1},
e) ^{3}A_{1} -(e -', e) 'A, 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) 'A , 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.