Formation enthalpies of Sn clusters:: a calorimetric investigation

The formation of a bulk Sn layer from a molecular beam of Sn, clusters has been directly investigated with a picojoule-sensitive calorimeter. The calorimeter is based on a microfabricated composite cantilever, and it makes use of the bimetallic effect. The formation enthalpy Delta H-f,H-298 for Sn(s) --> (I/N) Sn-N(g) has been determined from the released heat during the deposition of a distribution of Sn, clusters with a mean cluster size of [N] = 150 atoms. For this Sn cluster size distribution one obtains a formation enthalpy per atom of Delta H-f,H-298 = 0.45 +/- 0.19 eV. (C) 1999 Elsevier Science B.V. All rights reserved.