Solid clusters above the bulk melting point

The fact that the melting points of nanoparticles are always lower than tho se of the corresponding bulk material is a paradigm supported by extensive experimental data for a large number of systems and by numerous calculation s. Here we demonstrate that tin cluster ions with 10-30 atoms remain solid at similar to 50 K above the melting point of bulk tin. This behavior is po ssibly related to the fact that the structure of the clusters is completely different from that of the bulk element.