The lifetime of interatomic Coulombic decay (ICD) [L. S. Cederbaum et al., Phys. Rev. Lett. 79, 4778 (1997)] in Ne2 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 Ne2(+)(2s(-1)) state to be (150±50)  fs, in agreement with quantum calculations.

No abstract

No abstract

No abstract

Narrow graphene nanoribbons (GNRs) exhibit electronic and optical properties that are not present in extended graphene. Most importantly, they possess band gaps in the order of a few electron volts, which has been subject to numerous studies. Here we report on the experimental observation of exctionic states in the band gap of N = 7 armchair GNRs (7-GNR) on Au(111) and Au(788) using energy-and angle-resolved two-photon photoemission spectroscopy. Thereby, an exciton binding energy in the 7-GNR on Au(111) of 160 ± 60 meV has been determined. On the stepped Au(788) surface, the exciton binding energy is in the same range.