OXYGEN INTERACTION WITH RHODIUM AT LOW-PRESSURES

Oxygen adsorption and desorption on polycrystalline Rh and Rh(100) at P(O2) less-than-or-equal-to 10(-5) Pa and 400-1600 K have been studied using TDS and AES methods. Adsorption kinetics for both samples is described by the King model taking account of the effect of both precursor state and lateral interaction on O2 adsorption. Under desorption at low surface coverages (theta < 0.3) the adsorbed oxygen particles penetrate into the metal and then diffuse back to surface. At theta > 0.3 the processes of formation/decomposition of the surface oxide Rh2O3 take place. Adsorption and desorption data for both samples are close, which evidences a weak effect of the rhodium surface structure on these processes.