SUPERFULLERIDE FORMATION AND ELECTRONIC-PROPERTIES OF C60 ON K RH(111) SURFACES/

Despite the high electron affinity of C60, photoemission and work func tion measurements of C60 on Rh(111) surfaces containing submonolayer a mounts of K show that a low value of the work function is not sufficie nt to cause extensive charge transfer (> 1 electron) from the substrat e to the C60 molecule. However, when appropriate amounts Of C60 are ev aporated onto potassium multilayers of controlled thickness at 100 K, interdiffusion occurs and potassium superfullerides, KxC60 with 6 < x < 12, form on the surface. The resulting phases can be purified by ann ealing the sample to almost-equal-to 325 K for x-->12, or higher tempe ratures for lower K stoichiometries, to drive out excess K.