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

Abstract

Self-assembled monolayers (SAMs) by the spontaneous adsorption of alkylthiocyanate (ATC) on Au(111) were formed by solution and ambient-vapor deposition techniques at room temperature and 50 °C. The formation and structure of ATC SAMs were strongly influenced by alkylchain length, solvent, solution temperature and deposition techniques. Molecular-scale scanning tunneling microscopy imaging revealed that octylthiocyanate SAMs formed by vapor deposition technique have a (√3 × 2√19)R5° structure with long-range ordered domains, whereas decylthiocaynate SAMs have a mixed phase: a hexagonal (√3 × √3)R30° phase and a less-dense ordered phase. More detailed SAM characteristics were also examined by various surface sensitive techniques, such as X-ray photoelectron spectroscopy, thermal desorption spectroscopy, and cyclic voltammetry (CV), and will be discussed in this presentation.