Modification of the surface reactivity of Mo(110) upon carbide formation

The surface reactivity of thin molybdenum carbide films, prepared on a Mo(110) surface, has been investigated by using CO and ethylene molecules as chemical probes. Analytical techniques used include high-resolution electron energy loss spectroscopy (HREELS), Auger electron spectroscopy (AES), temperature-programmed desorption (TPD), low energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS). The carbide layers remain active towards the decomposition of CO and ethylene. Comparison with the clean Mo(110) surface as well as with the oxygen-modified Mo(110) surface indicates significant differences in surface reactivity of the molybdenum carbide films. These differences lend support to the assumption of an electronic modification upon surface carbide formation, rather than pure site-blocking by carbon atoms.