Adsorption of Phenacenes on a Metallic Substrate: Revisited

Phenacenes represent a class of simple hydrocarbons with appealing physical properties ranging from high charge mobility to superconductivity in combination with chemical robustness that are easily modified to serve as versatile building blocks for tailored structures. As a promising candidate for applications in organic devices, phenacenes are the focus of recent investigations. Thereby, the initial growth behavior starting from a single molecule is controversial. Here, we address the growth of [7]phenacene and [9]phenacene on a Ag(111) surface, studying the details of the initial stage of growth by scanning tunneling microscopy. According to our results, a previously introduced model involving a coverage-dependent phase change with the out-of-plane rotation of molecules in the initial growth stage can be disregarded. Instead, we find evidence for the formation of a new phase on top of an in-plane wetting layer during the initial stage of growth.