Structure of mercaptoalcohol self-assembled monolayers on Au(1 1 1)

Structures of mercaptoalcohols (1-mercaptohexanol: C6OH, 1-mercaptobutanol: C4OH and 1-mercaptopropanol: C3OH) 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 (8a0) for C6OH, 1.73 0.05 nm (6a0) for C4OH, and 1.44 0.04 nm (5a0) for C3OH; the stripe structure (stripe B), at high exposure, with the stripe distances of 1.19 0.04 nm (4a0) for C6OH and 1.01 0.03 nm (3.5a0) for C4OH; and the randomly distributed cluster-like structures at the highest exposure. Stripe B was not observed for C3OH. A (H3 H3)R308 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