Silver on : Alloying vs. surface reconstruction —two competing mechanisms to reduce surface stress

Department of Chemistry, University of Southern California Los Angeles, CA 90089-0482, USA

Corresponding author: koel@usc.edu

Received: 31 March 2003
Accepted: 18 July 2003

Abstract

Phase-coexistence of a surface-alloy and a pure -hex reconstructed phase has been observed for sub-0.3 coverage on a surface by scanning tunneling microscopy and temperature-programmed desorption of . We argue that, despite a stronger homoatom interaction, mixing at the surface is observed because the intrinsic tensile stress of the surface facilitates the incorporation of the slightly larger atoms into the surface layer in order to minimize strain energy of the surface. Thus, surface-alloying presents an alternative to surface reconstruction as a means of strain minimization. Therefore, a competition between surface reconstruction and alloying to reduce the stress at the surface exists and, consequently, a two-phase coexistence of an alloy-phase and a pure hex-reconstructed phase are observed.