Epitaxial Growth of Quinacridone Derivative on Ag(110)

The growth behavior of quinacridone derivative (QA16C) molecules on Ag(110) surface is studied using low-temperature scanning tunneling microscopy and low energy electron diffraction. At low coverage two distinct molecular orientations can be observed on silver terraces. At higher coverage up to 1 monolayer, depending on the growth temperature we observe two different structures on Ag(110) surface. At 100K the molecules organize in a complete monolayer on the surface, with a network-like structure. At 300K, the molecular orientation on the surface gives rise to row-like ordering, with a substantially higher molecular density. A theoretical analysis reveals that the structure of the molecular layer is controlled by the competition between molecular deposition rates and molecular diffusion along the surface.