Resonant single-photon double ionization driven by combined intra- and interatomic electron correlations

The double ionization of an atom by single-photon absorption in the presence of a neighbouring atom is studied. The latter is, first, resonantly photoexcited and, afterwards, transfers the excitation energy radiationlessly to the other atom, leading to its double ionization. The process relies on the combined effect of interatomic and intra-atomic electron correlations. It can dominate over the direct double photoionization by several orders of magnitude at interatomic distances up to a few nanometers. The relative position of the neighbouring atom is shown to exert a characteristic influence on the angular distribution of emitted electrons.