Systematic measurement of pentacene assembled on Cu(111) by bimodal dynamic force microscopy at room temperature

A wide range of depositions of pentacene on a Cu(111) surface was studied by frequency modulation bimodal dynamic force microscopy at room temperature. The morphologies and stabilities of the pentacene films were systematically studied via detections of the vertical and lateral tip-sample interactions at sub-molecular-scale resolution. At low coverage, pentacene adsorbs flat on the surface where two phases of molecular assemblies were observed. At the boundary between the different phase domains, a large magnitude of the dissipation energy, arising from the high mobility of pentacene, was measured while no significant increase of the dissipation energy was observed at the domain boundary of different orientations in the same phase. By increasing the amount of the deposited molecules, the second layer with the flatly aligned molecule tilted with a longitudinal molecular axis was observed over a small area, but most of the molecules moved to a certain site and formed crystallites with bulk structure on top of the first flat layer. We found that the work function of the bulk surface was strongly affected by the first flat layer.