L-shell X-ray energy shifts for an additional vacancy in the M-shell

A relativistic screened hydrogenic model is used to calculate the transition energy shifts of Ll, L eta , L beta 15 and L gamma 1 X-ray lines for a spectator vacancy in the M v subshell for Z=57 and Z=60-95 in steps of 5. It is pointed out that, although not very pronounced, the relativistic effect if quite interesting for the L X-ray spectra. Relativity is seen to play an opposite role in affecting the energy shifts for LM and LN transitions. A possible explanation of this is presented in terms of the concept of direct and indirect relativistic effects on atomic orbitals. The authors' values for 57 La agree quite well with the experimental results of Pepper et al. (1975). By comparing these results with the appropriate values of Parente et al. they find that quantum electrodynamic corrections are quite important in calculating L X-ray transition energy shifts.