Adsorption-site mixing at a continuous order-disorder phase transition

Abstract

The temperature-dependent probability of occupation of the two threefold-coordinated adsorption sites was determined for the system S/Ru(0001) at a coverage of 0.33, analyzing energy-dependent intensity curves [I(E) curves] in low-energy electron diffraction of the ordered 3 × 3 R30° phase and of the disordered system. We show that this probability agrees fully with a lattice gas model containing a finite difference in adsorption energy between these sites. © 1995 The American Physical Society.