Temperature Stability of Three Commensurate Surface Structures of Coronene Adsorbed on Au(111) from Heptanoic Acid in the 0 to 60 °C Range

Abstract

For the first time, accurate quantitative data on the temperature evolution of a surface monolayer formed at the solution solid interface are reported. In addition, a detailed analysis is provided of the structures of three different monolayers formed when coronene in heptanoic acid is in contact with Au(111). All three monolayer structures are well-defined epitaxial structures that are extremely stable for temperature variations between 0 and 60 °C. At high concentrations, a dense hexagonal structure with molecular separation of 1.19 ± 0.04 nm is observed. At reduced concentration, the most often observed structure is an open hexagonal epitaxial structure with one molecule per unit cell and a molecular separation of 1.45 ± 0.04 nm. This structure is stabilized by solvent molecule adsorption. If the dense phase is exposed to pure solvent, or occasionally with low concentration direct adsorption, then a different hexagonal phase is formed with three molecules per unit cell but exactly the same density (lat...