COMPETITIVE SURFACE INTERACTIONS OF WATER VAPOR AND OXYGEN ON Ni_3(Al,Ti) and Ni_3Fe SURFACES

摘要

The interaction of water vapor with singlecrystal Ni_3(Al,Ti) and polycrystalline Ni_3Fe, withand without the presence of oxygen, has been studiedwith Auger electron spectroscopy, photoemissionspectroscopy, thermal desorption and isotope exchange.Water dissociates to produce atomic hydrogen above 200K on both Ni_3(Al,Ti) and Ni_3Fe surfaces. ForNi_3(Al,Ti), the reaction is structure-sensitive.Pre-adsorbed or co-adsorbed oxygen on Ni_3(Al,Ti) andNi_3Fe significantly suppresses hydrogen productiondue to water dissociation. This suppression processoccurs more efficiently on Ni_3Fe than Ni_3(Al,Ti).