A Comparative Study on the Adsorption Behavior of Pentacene and Perfluoropentacene Molecules on Au(111) Surfaces

Abstract

In this study, we use low-temperature scanning tunneling microscopy and X-ray photoemission spectroscopy to study two closely related molecules, pentacene (PEN) and perfluoropentacene (PFP), adsorbed on a herringbone reconstructed Au(111) surface. PEN molecules are mobile under the probe tip at an elevated positive sample bias voltage with the direction of diffusion being correlated to the surface structure and the initial molecular orientation. Moreover, an induced rearrangement of the herringbone reconstruction is observable after manipulation. PFP molecules rearrange into flat, densely packed islands and the herringbone structure is undisturbed by the adsorbed PFP molecules. In addition, the X-ray photoelectron spectroscopy (XPS) C 1s and F 1s core level spectra of PFP show a shift toward high binding energy at high coverage. In comparison only a subtle shift for the C 1s core level of PEN at high coverage is seen. This indicates a different molecular arrangement for PFP in the bulk and in close proximity to the gold substrate.