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Chemical Physics Letters 265 (1997) 490-496
(LS) versus (jj) coupling in P 2p inner-shell excited states of PF₃

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

^aInstitute for Molecular Science, Okazaki 444, Japan ^bChemistry, University of Alberta, Edmonton, Alb., Canada T6G 2G2 ^cChemistry, McMaster University, Hamilton, Ont., Canada L8S 4MI Received 14 October 1996; in final form 5 December 1996

Abstract
The P 2p total and parent ion yield spectra of PF₃ have been measured and interpreted with ab initio SCF-CI calculations. The PF₃⁺ yield has only one line at 136.5 eV, without a spin-orbit partner. The ab initio calculations attribute it to the (e -', e)¹A₁ state. They predict the (e ^{- 1}, e) ³A₁ -(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.