Adsorption and decomposition of methane on gallium oxide films

Surface reactions are investigated by a sensitive mass spectrometer. Ga2O3 films are exposed to square pulses of methane. From the experimental data t he desorption energies and the frequency factors are calculated for H2O and CO2. Semiempirical Hartree-Fock calculations with the Modified Neglect of Diatomic Overlap - Parametric Method 3 (MNDO-PM3) method give information a bout the adsorption process. The energy gain of physisorption amounts to 0. 27 eV. The Heat of Formation (HoF) of the chemisorbed CH3 group and the H a tom is 4.05 eV lower in comparison to the value of the physisorbed methane. After the COlatt, group formation the energy gain is 7.33 eV. The binding energy of the formed COlatt, is calculated to 2.07 eV. The charge transfer is estimated using the Mulliken charges. A reaction scheme for the catalyti c oxidation of methane by lattice oxygen is proposed. (C) 1999 Elsevier Sci ence S.A. All rights reserved.