Interatomic Coulombic decay following Ne 1s Auger decay in NeAr

Using momentum-resolved electron-ion multicoincidence spectroscopy, we have investigated interatomic Coulombic decay (ICD) in the heteronuclear NeAr dimer following Ne 1s Auger decay. The measured intensity ratio for the three ICD transitions Ne{sup 2+}(2s{sup -1}2p{sup -1} {sup 1}P)Ar to Ne{sup 2+}(2p{sup -2} {sup 1}S)-Ar{sup +}(3p{sup -1}), Ne{sup 2+}(2s{sup -1}2p{sup -1} {sup 1}P)Ar to Ne{sup 2+}(2p{sup -2} {sup 1}D)-Ar{sup +}(3p{sup -1}), and Ne{sup 2+}(2s{sup -1}2p{sup -1} {sup 3}P)Ar to Ne{sup 2+}(2p{sup -2} {sup 3}P)-Ar{sup +}(3p{sup -1}) reasonably agree with predictions. The kinetic energy release distribution for the fragmentation to Ne{sup 2+}(2p{sup -2} {sup 1}D)-Ar{sup +}(3p{sup -1}) after the ICD transition from singlet Ne{sup 2+}(2s{sup -1}2p{sup -1} {sup 1}P)Ar state, which is a mirror image of the kinetic energy distribution of the emitted ICD electrons, suggests that the corresponding ICD rate is roughly two times lower than predicted by ab initio calculations.