Room temperature stability of mass selected Ag clusters on C$_{60}$ functionalized surfaces*

Mass selected clusters from Ag$^+_{55}$ to Ag$^+_{561\pm5}$ were soft landed on HOPG and Au(111) functionalized with 1 and 2 monolayers (ML) of C$_{60}$ molecules [1]. Depositions at 165 \,K gave extremely narrow cluster height distributions in STM images measured at 77\,K. Using C$_{60}$/HOPG or 2\,ML C$_{60} $/Au(111) the cluster heights are stable for more than 12\,h at room temperature (RT). For 1\,ML C$_{60}$/Au(111) the cluster height decreases and finally all clusters disappear at RT. Molecular dynamics simulations reveal a process by which the clusters decay atom by atom through 1\,ML C$_{60}$/Au(111) at RT. A sharp maximum at 1.7\,nm cluster height forms during the cluster decay, indicating that there exists some metastable 'supported magic number'. \par \noindent [1] S. Duffe et al., Eur. Phys. J. D (2007), published online