Periodic step-bunching on a miscut Pt(111) surface

The temperature dependence of the equilibrium surface morphology of a stepped Pt(111) surface, miscut by 1.8° towards [1̄1̄2], has been studied by X-ray scattering techniques between 300 and 1900 K. Below T c = 1389 K, the surface is found to be uniformly stepped and unreconstructed. Above T c, the surface transforms into a periodic array of wide terraces and narrow terraces. Unlike macroscopic facets, the wide terraces are mesoscopic in extent, ranging from 230 Å at 1389 K to 94 Å at 1900 K. Reflectivity measurements suggest that multiple-height steps are not prevalent. The wave vector characterizing the array (δ) follows a power law versus reduced temperature [t = (T - T c ) T c ] : δ = δ 0t \ ̄ gb with \ ̄ gb = 0.66 ± 0.05 .