Structural Evolutions of the Self-Assembled <i>N</i>‑Decyldecanamide on Au(111)

The self-assembly of N-decyldecanamide (DDA) on Au(111) is investigated by means of scanning tunneling microscopy under ultrahigh vacuum conditions. Four self-assembled phases have been observed by varying the molecular coverage and the evaporation temperature. At lower coverage, the self-assembled phase with lowest Gibbs free energy is preferred, suggesting the self-assembly at low coverage is thermodynamically driven. At fixed evaporation temperature, the increasing of the molecular coverage results in the phase transitions from sparse packing to dense ones. On the basis of the systematic study of the self-assembly structures of DDA on the Au(111) surfaces, a phase diagram is eventually obtained. This study provides means to control the phase transitions on Au(111) surfaces by altering the balance of thermodynamic and kinetic effects