Evaporation of Metal Clusters
The evaporation of sodium clusters on an insulator single crystal surface has been investigated. For this purpose the substrate was heated slowly, and sodium atoms desorbing from the cluster surface were detected with a mass spectrometer. We demonstrate that the resulting spectra can be used to extract cluster binding energies as a function of cluster size. They approach the bulk value for clusters containing as many as 106 to 107 atoms. This is consistent with theoretical calculations.