Formation and annealing effect of tolanethioacetate self-assembled monolayers on Au(111)

Abstract

Self-assembled monolayers (SAMs) were formed by adsorption of thioacetyl-terminated tolanethioacetate (TTA) on Au(111) in a 0.5-mM ethanol solution after one day immersion at room temperature. Molecular-scale STM imaging revealed that the TTA SAMs were composed of two mixed phases; an ordered phase with small domains describing a (root 3 x 2 root 3)R30 degrees structure and a disordered phase. Interestingly, after annealing the precovered TTA SAMs on Au(111) at 90 degrees C for 1 h, the small ordered domains grew unidirectionally, resulting in the formation of unique rod-like domains, which were assigned a (root 3 x 2 root 3)R7 degrees structure. These results will be very useful in understanding the formation and thermal behavior of TTA SAMs on gold surfaces.