CHEMISORPTION OF OXYGEN ON Au (111) SURFACE

The chemisorption of oxygen on Au (111) surface has been studied by low energy electron diffraction (LEED) and photoemission spectroscopy (PES). Oxygen was found to begin adsorbed on clean Au(ll1) surface at a temperature above 600°C and an oxygen pressure 5x10^-6mbar. The chemisorbed oxygen was very stable and could not be removed by heating up to 85°C . The widening of the Au 4f XPS peak and two new peaks in UPS were observed. The LEED observation showed that a structure with two twisted domains of hexagonal close packed oxide (AuO_x) overlayer was formed at the initial oxygen adsorption, and with further oxygen exposure another (√3 x√3 ) R30°structure was formed on the twisted oxide-overlayer.