Interaction of oxygen with a clean Ir(111) surface

Abstract

HREELS and XPS methods were used for the investigation of the interaction of oxygen with Ir(111). At temperatures of 180 and 300 K oxygen is adsorbed dissociatively, 0.52±0.08 oxygen atoms per one Ir atom corresponding to a saturated coverage. Adsorbed oxygen atoms are characterized by a v (Ir-O) mode at 550 cm −1 . With rising temperature (above 300 K) diffusion of oxygen atoms into the subsurface Ir layer begins. At 600 K and an oxygen pressure of 1×10 −5 Pa, formation of a surface oxide begins which characterizes the initial stage of Ir(111) oxidation. A v (Ir-O) peak at about 800 cm −1 in the HREEL spectrum corresponds to the surface oxide. More intensive oxidation of Ir(111) proceeds at 850 K and an oxygen pressure of 0.1 MPa, the surface oxide formed differing in composition from IrO 2 .