Layer growth and desorption kinetics of a discoid molecular acceptor on Au(1 1 1)

The layer growth and desorption kinetics of discoid organic acceptor molecules hexaazatriphenylene-hexacarbonitrile (HAT-CN) on Au(1 1 1) have been studied by thermal desorption spectroscopy (TDS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and X-ray diffraction (XRD). The molecules form two wetting layers of flat lying molecules when evaporated at or below room temperature. Increasing the coverage beyond two monolayers and upon heating of the sample a destabilization of the 2nd layer and subsequently of the 1st layer takes place and 3D islands are formed. A quite unusual desorption behavior is observed for the individual layers, which is discussed in detail.