Structural Transition and Thermal Stability of a Coronene Molecular Monolayer on Cu(110)

Abstract

A series of alternating structural transitions of coronene monolayers on Cu(110) surfaces are observed using in situ molecular beam epitaxy with low-energy electron diffraction when varying substrate temperature after deposition. The first transition is observed around 293 K, and the second one happens at 360 K. By employing molecular mechanics and density functional theory calculation, it is found that the first transition is due to the transition from physical adsorption to chemical adsorption, while the second transition can be explained by the adsorbed molecules diffusing from a metastable site to a thermodynamically more stable site. Moreover, the unchanged diffraction pattern in the subsequent cooling and reheating process indicates that the final monolayer structure has a high thermal stability. These transitions were compared with the reversible transitions of coronene on Ag(110).