The reaction of MO(CO)6 on aluminum films grown on a Mo(100) substrate at 700 K is explored in ultrahigh vacuum using temperature-programmed desorption (TPD) and Auger and X-ray photoelectron (XPS) spectroscopies. Reaction with MO(CO)6 at 700 K results in some oxidation of the outer layer of the aluminum film, and the formation of a molybdenum carbide, which incorporates some oxygen. The carbide stoichiometry varies initially from approximately MoC for carbonyl reacting with the aluminum surface, to Mo2C for thicker films. Heating this film to similar to 1200K results primarily in the desorption of carbon monoxide due to a reaction between the carbide and aluminum oxide. Metallic aluminum diffuses from the bulk of the film and some aluminum is found to desorb from the surface at similar to 1270 K so that aluminum is retained on the surface due to the presence of the carbonyl-derived film. It is suggested that the aluminum can form an alloy with molybdenum at these higher temperatures. (c) 2005 Elsevier B.V. All rights reserved.