Diffusion and aggregation of Agn-clusters (n = 2-9) on HOPG probed by fs-two-photon-photoemission U. Busolt, E. Cottancin, L. Socaciu, H. Röhr, T. Leisner and L. Wöste Eur. Phys. J. D, 16 1-3 (2001) 297-300 Published online: 15 September 2001 DOI: 10.1007/s100530170114