Disordered structure of Pt(1 1 1)-p(2 × 2) induced by synchrotron X-ray beam irradiation

Surface-structure analysis of a disordered 2 × 2 phase on Pt(1 1 1) was carried out utilizing surface X-ray diffraction under grazing incidence condition with a synchrotron X-ray beam (SPring8, Nishiharima). The structure of an ordered Pt(1 1 1)-p(2 × 2)–O surface started losing its threefold symmetry immediately after 3 min of X-ray beam irradiation at 25 K. A disordered new phase of a Pt(1 1 1)-2 × 2 surface was stabilized and supplied to intensity measurements. Structure analysis using Texan software of the new phase of the Pt(1 1 1)-2 × 2 surface revealed the existence of remarkable displacements of platinum atoms over ten surface platinum layers in contrast to the buckled Pt(1 1 1)-2 × 2–O surface structure observed by LEED. The maximum in-plane and out-of-plane displacements from the bulk-phase positions were found to be 0.017(5) and 0.040(5) nm, respectively.