Lifetime broadening and CI-resonances observed in ESCA

The electron spectrum of the M2 and M3 levels in bromine and krypton have been studied by high resolution ESCA. The M1Msub(2,3) super Coster-Kronig transitions become energetically forbidden for Z >approximately 36 (Kr) and recent calculations therefore predict a decrease in the M2 and M3 natural linewidths around krypton in the periodic system. The experiment shows that the 3psub(3/2) linewidth is smaller in Kr than in Br. It is, however, also found that this decrease in linewidth is followed by configuration interaction (CI) between 3p 2P and 3d2 nl * 2P states. Several discrete CI resonances are observed in the Kr 3p spectrum. Such resonances are also studied in the N shell for the elements from Te(Z=52) to Ba(Z=56). For these elements the effect is found to be much larger due to the strong collective character of 4d-nf* excitations. (Auth.)