Journal of Molecular Catalysis A-Chemical, Vol.209, No.1-2, 135-144, 2004
The effect of electron beam irradiation on the chemistry of molybdenum hexacarbonyl on thin alumina films in ultrahigh vacuum
The interaction of incident electron beams with molybdenum hexacarbonyl (MO(CO)(6)) adsorbed on thin, dehydroxylated alumina films grown on a molybdenum substrate is studied in ultrahigh vacuum using primarily temperature-programmed desorption (TPD) and reflection-absorption infrared spectroscopies (RAIRS). It is found that electron beams induce decarbonylation, forming both subcarbonyls and a stable surface oxalate species, where it is found that a MO(CO)(2) species is the precursor to the formation of oxalate species. A similar oxalate species is formed on dehydroxylated alumina by heating a MO(CO)(6)-covered surface to above similar to205 K, but the amount formed by electron beam irradiation is similar to3.5 times larger. It is shown that electron beam energies of similar to10 eV or greater are required to cause extensive decarbonylation and that the majority of the surface decomposition is caused by an electron dose of similar to6 mC/cm(2) (C) 2003 Elsevier B.V. All rights reserved.
Keywords:reflection-absorption infrared spectroscopy;temperature-programmed desorption;chemisorption;molybdenum hexacarbonyl;alumina thin films;electron beams