Double photoionization into double core-hole states in Xe

Double photoionization (DPI) leading to double core-hole states of Xe2+ 4d-2 has been studied using a magnetic bottle time-of-flight spectrometer. The assignments of the Xe2+ 4d-2 states are confirmed by the Auger lines extracted from fourfold coincidences including two photoelectrons and two Auger electrons. It is estimated that the core-core DPI into Xe2+ 4d-2 at a photon energy of 301.6 eV has a favored cross section of about 0.3 MB. The intense core-core DPI is due to mixing of the 4d-2 continuum with the 4p single photoionization, which is manifested in the relative intensities of the Xe2+ 4d-2 components.