The critical temperatures of the first three layers of Xe on a stepped surface of Pd, as well as the roughening temperature, have been recently measured by Miranda et al. These temperatures are about half those expected from theory for homogeneous infinite surfaces. Here we propose that this dramatic decrease is due to the finite size of the terraces in the stepped surface and to the existence of preferential adsorption sites along the steps.

• Received 2 April 1984

DOI:https://doi.org/10.1103/PhysRevLett.53.822