Time-Resolved Measurement of Interatomic Coulombic Decay in Ne2

The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al., Phys. Rev. Lett. 79, 4778 (1997)] in Ne-2 is determined via an extreme ultraviolet pump-probe experiment at the Free-Electron Laser in Hamburg. The pump pulse creates a 2s inner-shell vacancy in one of the two Ne atoms, whereupon the ionized dimer undergoes ICD resulting in a repulsive Ne+ (2p(-1)) - Ne+ (2p(-1)) state, which is probed with a second pulse, removing a further electron. The yield of coincident Ne+ - Ne2+ pairs is recorded as a function of the pump-probe delay, allowing us to deduce the ICD lifetime of the Ne+ (2s(-1)) state to be (150 +/- 50) fs, in agreement with quantum calculations.