Pt-dimer dissociation on Pt(111)

An analysis of the temperature dependence of Pt-island number densities on Pt(1 1 1) and ab initio density functional theory calculations agree that t he activation energy for Pt-dimer dissociation on Pt(1 1 1) is between 0.79 and 0.88 eV. This result is much larger than the value 0.49 +/- 0.01 eV ob tained from field ion microscopy (FIM). The discrepancy is attributed to ea sy dimer access to the boundaries of the apex (1 1 1)-plane on a Pt FIM tip , where dissociation is facile. (C) 2001 Elsevier Science B.V. All rights r eserved.