AES study of the adsorption of O2, CO, CO2, and H2O on indium

The adsorption of various oxygen-containing gases on clean polycrystalline In has been studied. For the In-O2 system, the relationship between N(E) areas and dN(E)/dE peak heights for the In MNN Auger transition was found to be linear. At saturation, an oxygen/indium ratio of 3/2 was measured, consistent with the formation of the stable oxide In2O3. Low coverage sticking coefficients were found to be approximately .014 for O2, approximately .004 for H2O, approximately 5 x 10-5 for CO, and approximately 2 x 10-5 for CO2. In each case, chemical shifts and peak distortions in the N(E) and dN(E)/dE spectra have been measured for the gas-saturated In, the largest being approximately 3 eV for the MNN transition of O2-saturated surface