Temperature and coverage driven condensation of pentacene on the Si(111)-–Ag surface

Abstract

The adsorption and self-assembly behavior of pentacene molecules on theSi(111)-–Ag surface has been studied by variable-temperature scanning tunneling microscopy(STM). By cooling the surface from room temperature to 120 K we observed thecondensation of a two-dimensional molecular gas phase to a new ordered solid phase (P2).The structure models of this phase and the high-density brick-wall phase (P1) areproposed consistently based on a systematic investigation of the morphology,chirality and domain boundary structures of the two phases. The self-assemblymechanism of pentacene molecules driven by temperature and molecular coverage isdiscussed.