X-RAY-DIFFRACTION AND ELECTROCHEMICAL STUDY ON THE OXIDATION OF FLAME-ANNEALED AU(100) SINGLE-CRYSTAL SURFACES

A comparison of the surface structure and the cyclic voltammograms of a Au(100) single crystal surface after various non-UHV preparation tec hniques has been made. Comparisons were made between two flaming tempe ratures, above and below the annealing transition temperature, and two cooling methods (air and water quenching). A chemical cleaning method was also used as a standard for the flame results. None of the prepar ation techniques produced a (5 X 20) reconstruction as measured by sur face X-ray diffraction. The high temperature annealing produced the sm oothest surface; however, the bulk mosaics, as measured by the full wi dth at half maximum of the (0, 0, 2) reflection, were increased. Upon immersion in 0.1 M HClO4 at +0.4 V/SCE asymmetry in the (0, 0, l) spec ular rod associated with the (5 X 20) reconstruction was observed. The increased mosaics associated with an increase in the surface defects resulted in the growth of the oxidation peak at +0.95 V/SCE in the cyc lic voltammogram.