Coadsorption of potassium and oxygen on Fe(110)

Abstract

The interaction of oxygen was studied on clean and potassium covered Fe(110) using XPS, UPS, AES and LEED. The chemisorption phase of oxygen on potassium covered Fe(110) is characterized by oxygen-iron bonds and the lack of a formation of potassium oxide as long as the potassium coverage is one monolayer or less. The initial sticking coefficient for oxygen increases from 0.13 for clean Fe(110) to 1.0 for Fe(110) covered with a monolayer of potassium. Coadsorption of potassium and oxygen gives an ordered c(4 × 2) LEED structure at coverage θO = 0.5 and θK = 0.28. The chemisorption of oxygen at room temperature may be followed by penetration into the subsurface region prior to the oxide formation. For Fe(llO) with and without potassium the oxidation/penetration initiates at an oxygen coverage of 0.4–0.5.