Epitaxial nanolayers of quaterrylene: Influence of the substrate on the growth of the first and second monolayers

We present a combined low energy electron diffraction and scanning tunneling microscopy study on the growth of the first and second monolayers (MLs) of quaterrylene on single crystalline Au(111). For the first ML, we observe a point-on-line coincident growth of flat lying molecules which agrees well with our potential energy calculations. In contrast, we observe alternating upstanding and flat lying molecules in the second layer. This behavior nicely demonstrates that the substrate has a very strong influence on the structure of the first layer, whereas the second layer is much weakly affected and exhibits properties comparable to the bulk. (c) 2006 American Institute of Physics.