Self assembly of 16-mercapto-1-hexadecanol on gold: surface characterization and kinetics

The chemical composition, film structure and surface wetting properties at different self-assembly formation stages for 16-mercapto-1-hexadecanol on gold were investigated in this work. Complementary surface analytical techniques (ESCA, infrared reflection absorption spectroscopy (IRAS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and contact angle measurements) explored the progression of self-assembly at a molecular level from different perspectives. At the earlier stages during the formation of a self-assembled monolayer, molecules adsorbed onto the gold surface in a manner suggesting island growth. This was followed by a slower process where the monolayer underwent a phase transition by conformational reconstruction and realignment of molecular axes with the surface normal. The contact angle behavior can be related to surface coverage as well as molecular orientation. In integrating spectroscopic, thermodynamic and kinetic data, a clearer picture was obtained about mechanistic and structural aspects of self-assembled molecular thin films.