ELECTRON-BEAM DAMAGE OF C-60 FILMS ON HYDROGEN-PASSIVATED SI(100)

We report the effects of medium-energy (3.5 keV) electron-beam irradia tion of C-60 films between and 4 ML thick grown on Si(100) 2x1-H studi ed by high-resolution electron energy-loss spectroscopy. Electron irra diation leads primarily to molecular fragmentation. Initially, molecul ar fragments are discrete, and saturated with hydrogen, but continued irradiation leads to the formation of a disordered material with a gra phitic local structure. Experiments performed on a single monolayer of C-60 show that under irradiation, fragments can bond to the substrate via displacement or desorption of the hydrogen atoms bonded to the Si substrate. (C) 1998 American Institute of Physics.