Binding energy and electronic properties in antimony clusters: comparison with bismuth clusters

Antimony clusters are produced by the gas aggregation method. They are found to be built from Sb4 units. The Sb+4n clusters are demonstrated to relax their excess energy by evaporation of a tetramer and the binding energy of Sb4 in the cluster is measured to be about 1.3 eV, well below the binding energy of a Sb atom in the bulk (≊2.75 eV). The ionization potentials of Sb4n clusters are studied as a function of the size and the observed evolution confirms the nonmetallic character of their structure. These results are compared with those obtained for bismuth clusters which exhibit a very different behavior. Finally the possible metastable character of Sb4n structure is discussed and illustrated by experiments performed as a function of inert gas temperature in the clusters source.