The L2:L3 intensity ratio in soft X-ray emission spectra of 3d-metals

We present L2,3 X-ray emission spectra of the 3d-metals Ti through Cu. It is found that the ratio of the integrated non-resonant emission intensities of L2 to L3 emission, I(L2)/I(L3), is approximately two times smaller than the ratio of the core hole state degeneracies (L2/L3 = 1/2). Our atomic calculations show that the L2L3M4,5 Coster-Kronig transition is responsible for the reduction of the I(L2)/I(L3) intensity ratio and explains its gradual decrease with increasing atomic number among the 3d transition metals. For the resonant case we find that accounting for the core-hole interaction and local field effects via TDDFT satisfactorily explains the changes in the I(L2)/I(L3) ratio.