Reactivity of Mo2C/Mo(1 0 0) toward oxygen: LEIS, AES, and XPS study

Ion scattering spectroscopy (LEIS) was used in conjunction with X-ray photoelectron (XPS) and Auger electron spectroscopies (AES) for the study of the structure and the reactivity of surface Mo2C prepared on Mo(1 0 0). At 1265 K the carbide phase transformed into an oxide layer in the presence of O2. The oxidation starts in the outermost layer but at higher oxygen exposition subsurface O is also formed. LEIS results suggest the existence of different adsorption centers for O in the topmost layer. Carbon could be completely removed both from the first layer and from deeper regions as was shown by LEIS and AES. The carbidisation of the oxide phase with high temperature decomposition of ethylene was also investigated. After several carbidisation cycles approximately clean Mo layer could be achieved as an intermediate state. At higher ethylene exposures carbide accumulates simultaneously in the different layers of the surface region.