Adsorption of Oxygen on K_xC₆₀ Studied by Photoelectron Spectroscopy

Photoemission spectra of vacuum deposited K-incorporated C₆₀–K_xC₆₀( x≈6 ) , before and after exposure to oxygen, show that the interaction between oxygen and potassium forms an overlayer of 40Å 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.