The adsorption of an n-hexadecane/benzoic acid solution onto highly oriented pyrolytic graphite studied by atomic force microscopy

Atomic force microscopy has been used to study structures formed on the surface of highly oriented pyrolytic graphite following the evaporation of a binary solution of n-hexadecane (C16H34) and benzoic acid (C6H5COOH). Previous work on the evaporation of n-hexadecane revealed the graphite surface to be decorated with two species of isolated features on the terraces and continuous features at the steps. Models were proposed, describing the molecular orientations within the features that were dependent on the length of the n-alkane molecule. Similar structures are observed on the graphite surface following the evaporation of the binary solution. The results of the experiments reported here are compared to the previous experiments of hexadecane alone, allowing a determination of the effect of the acid on both the structures and the coverage. (C) 1999 Elsevier Science B.V. All rights reserved.