Electron-energy-loss spectroscopy of C60 monolayer ®lms on active and inactive surfaces

The characteristics of interaction between C60 molecules and Si(1 1 1)-7 7, Ag/Si(1 1 1)-p3 p3 R308 and layered material MoS2 surfaces have been investigated using electron-energy-loss spectroscopy (EELS). The EEL spectrum of C60/ Si(1 1 1)-7 7 shows a new peak at loss energy of 2.7 eV. This indicates the existence of charge transfer from the substrate to C60 molecules. The EEL spectrum of a C60 monolayer ®lm grown on a cleaved surface of MoS2 is almost the same as that of bulk C60. The EEL spectrum of a C60 monolayer ®lm on an Ag/Si(1 1 1) surface is quite different from that on a clean Si(1 1 1)-7 7 surface, although the ®lms on those substrates have the same epitaxial arrangement. Furthermore, intensities of energy-loss peaks of C60/Ag/Si(1 1 1) are slightly smaller than those of C60/MoS2 in spite of having the same loss-energy. This suggests that the interaction between C60 molecules and the Ag/Si(1 1 1) surface is stronger than that between C60 molecules and the MoS2 surface. # 2001 Elsevier Science B.V. All rights reserved.