Structure of mercaptoalcohol self-assembled monolayers on Au(111)

Abstract Structures of mercaptoalcohols (1-mercaptohexanol: C 6 OH, 1-mercaptobutanol: C 4 OH and 1-mercaptopropanol: C 3 OH) were studied with scanning tunneling microscopy (STM) and density functional theorem (DFT) calculations. Three structures were observed depending on the exposure of mercaptoalcohols: the striped structure (stripe A), at low exposure, with the stripe distances of 2.30 ± 0.07nm (8 a 0 ) for C 6 OH, 1.73 ± 0.05 nm (6 a 0 ) for C 4 OH, and 1.44 ± 0.04 nm (5 a 0 ) for C 3 OH; the stripe structure (stripe B), at high exposure, with the stripe distances of 1.19 ± 0.04 nm (4 a 0 ) for C 6 OH and 1.01 ± 0.03 nm (3.5 a 0 ) for C 4 OH; and the randomly distributed cluster-like structures at the highest exposure. Stripe B was not observed for C 3 OH. A (√3 × √3) R 30° related structure, which is the highest coverage structure for alkanethiols on Au(1 1 1), was not observed. The structures are uniquely determined by the formation of hydrogen bonding.