Adsorption of Oxygen on K x C 60 Studied by Photoelectron Spectroscopy

Photoemission spectra of vacuum deposited K-incorporated C60–KxC60 (x ≈ 6), before and after exposure to oxygen, show that the interaction between oxygen and potassium forms an overlayer of 40 A K-O complex with stoichiometry near to that of potassium peroxide K2O2 on the surface. In contrary to the oxidation of potassium film, no potassium oxide K2O has been observed.