Electron-stimulated conversion of chemisorbed o to Al2O3 on Al(111)

The transformation of a chemisorbed O layer on the Al(111) surface into Al2 O3 under electron impact has been monitored by high-resolution electron ene rgy-loss and x-ray photoelectron spectroscopies. Electron irradiation (100 eV) of chemisorbed O was observed to cause spectroscopic changes in the sur face layer indicative of oxide formation. The energy transfer from the elec trons to the chemisorbed O atoms through electronic excitations, leading to vibrationally excited adsorbed particles, is proposed to be responsible fo r the observed conversion of chemisorbed oxygen to Al2O3. The cross section for this electron-induced process is estimated to be 2 x 10(-19) cm(2) for 100 eV electrons. (C) 1999 American Institute of Physics. [S0003-6951(99)0 2746-1].