SPECTROSCOPIC CHARACTERIZATION OF THIN VANADIUM CARBIDE FILMS ON A VANADIUM(110) SURFACE - FORMATION, STABILITY, AND REACTIVITIES

The surface properties of thin vanadium carbide films, produced on a V(110) surface, have been investigated by using a combination of high-resolution electron energy-loss spectroscopy, fluorescence-yield near-edge x-ray absorption spectroscopy (FYNES), and Auger electron spectroscopy (AES). Our results indicate that thin carbide films with a stoichiometry of VC can be produced by exposing V(110) to olefin molecules at 600 K. A comparison of the bulk-sensitive FYNES data with the relatively surface-sensitive AES results suggests that the average thickness of the VC film is greater than the penetration depth of Auger electrons for the C(KLL) and {LMM) transitions. Upon heating to 600–1050 K, the thin VC films most likely undergo a thermally induced clustering process, which is followed by a diffusion of carbon atoms into the bulk V(110). The surface reactivities of the carbide-modified surfaces are significantly different from those of either clean V(110) or oxygen-modified V(110), as will be demonstrated by the interactions of these surfaces with CO and ethylene molecules. © 1995, American Vacuum Society. All rights reserved.