Complete Double Valence Photoionization Study Of The Electron Spectra Of Krypton

Double photoionization spectra of Kr have been recorded using monochromatized synchrotron radiation of 88 eV photon energy and a versatile multielectron coincidence time-of-flight spectroscopy technique. The formation of the Kr2+ states of the lowest-energy configuration 4s(2)4p(4) is partly direct, producing electron pairs with a continuous distribution, and partly indirect via superexcited singly ionized states. The superexcited Kr+ states show strong and hitherto unexplained selectivity in branching to final Kr2+ states. Kr2+ states based on excited configurations are formed mainly by direct double photoionization.