INTERFACE EFFECTS IN MELTING OF PB CLUSTERS ON THE CU(111) SURFACE

The growth and melting transition of Pb clusters on the Cu(111) surfac e have been studied with low energy electron microscopy. Kinetic growt h and equilibrium cluster shapes are distinguished and a systematic va riation of the melting temperature among individual clusters in an ens emble has been observed. A simple thermodynamic model is proposed whic h accounts for this unusual melting behaviour through known finite siz e and new interface effects. The role of the interface roughness, e.g. atomic steps, in modifying the interface tension between adsorbate an d substrate is suggested by these results.