We investigated(C59N)2multilayer films, intercalated with different amounts of potassium, by electron energy loss spectroscopy and by synchrotron radiation techniques. For low K exposures, valence band photoemission shows, apart from a rigid shift towards higher binding energies of the whole spectrum, two new LUMO-derived peaks, indicative of a mixture of phases. One of the doped phases still preserves the dimer structure. At K concentrations, the(C59N)2dimer breaks up, as seen by HREELS, but the dimer phase can be recovered by distillation. C1s and K2p photoemission spectra show two K sites up to aboutK3C59Nand one K site for higher K concentrations. ©2001 American Institute of Physics.