One-photon, multielectron excitation in the L atomic levels of thulium

Discontinuities attributed to multielectron excitations were observed in the X-ray absorption spectra of thulium ( 69 Tm). They were identified as being the results of 2s -2 , 2s -1 +2p 1 2/ -1 , 2p 1 2/ -2 , 2p 1 2/ -1 +2p 3 2/ -1 and 2p 3 2/ -2 excitations. Their measured energies and the results of a non-relativistic Hartree-Fock calculation are in general agreement. The observed splitting of the (2s -1 +2p 1 2/ -1 ) discontinuity was explained on the basis of intermediate coupling calculations. The cross sections of these discontinuities were found to be between 1.6+or-0.4 and 1.9+or-0.4 per cent of the L 3 -absorption cross section of the element.