Formation and Structure of Self-Assembled Monolayers by Adsorption of Octaneselenocyanate on Au(111)

The formation and surface structure of self-assembledmonolayers (SAMs) on Au(111) by adsorption of octaneselenocyanate (C8Se-CN) in a 1 mM ethanol solution were examined by scanning tunneling microscopy (STM) and cyclic voltammetry (CV). STM imaging reveals that octaneselenolate (C8Se) SAMs formed at room temperature were mainly composed of disordered phase containing many vacancy islands, whereas well-ordered C8Se SAMs with a row structure were formed at high solution temperature of 50 or 75 degrees C. Spacing between the rows was measured to be 1.7 +/- 0.2 nm, and molecular spacing in the row was measured to be 0.5 +/- 0.1 nm. From this work, we clearly demonstrated that C8Se-CN molecules on Au(111) at high solution temperature led to the formation of ordered C8Se SAMs after bond cleavage of C8Se-CN. Our results will provide new insight into understanding the formation and structure of SAMs by the adsorption of C8Se-CN molecules on Au(111) surface.