Dynamic scanning probe microscopy of adsorbed molecules on graphite

We have used a combined dynamic scanning tunneling and atomic force microscope to study the organization of weakly bound adsorbed molecules on a graphite substrate. These weakly bound molecules may be imaged in dynamic scanning tunneling microscopy (STM) mode in which the probe is oscillated above the surface. We show that molecular resolution may be readily attained and that a similar mode of imaging may be realized using conventional STM arrangement. We also show, using tunneling spectroscopy, the presence of an energy gap for the adsorbed molecules confirming a weak molecule-substrate interaction.