Strong configuration interaction in the 3p photoelectron spectrum of Kr

We measured the Kr photoelectron spectrum in the region close to the 3p ionization threshold. Our high-resolution measurements allowed a clear observation of spectral structures due to electron correlation effects. Analysis based on relativistic multiconfiguration calculations could explain these observed peaks as due to strong configuration interactions between the 3p(-1) state and 3d(-2) nl states. Calculated and experimental data for peak assignments and intensity distributions are in good agreement. In addition, we measured the anisotropy parameter beta, which also agreed well with theory. These findings provide a detailed view of strong configuration interactions between the 3(-1) and 3d(-2)nl inner-shell hole states.