Investigations of C molecules deposited on Si 111/by 60 noncontact atomic force microscopy

We demonstrated the high resolution imaging of the organic molecules using noncontact atomic force microscopy in ultrahigh vacuum. The sample was C60 molecules deposited on the Si 111.-7=7 reconstructed surface. When the thickness of the C60 film was submonolayer, we could image some isolated C60 molecules and the reconstructed Si surface simultaneously. However, the imaging was highly unstable not only because of the large structure but also due to the large difference between the interaction forces on the molecules and on the Si surface. On the other hand, when the thickness of the C60 molecules was almost monolayer, individual molecules could be stably imaged. q1999 Published by Elsevier Science B.V. All rights reserved