11-Hydroxyundecyl octadecyl disulfide self-assembled monolayers on Au(111)

Here, we report a helium atom diffraction study of 11-hydroxyundecyl octadecyl disulfide (CH3-(CH2)17-S-S-(CH2)11-OH, HOD) self-assembled monolayers (SAMs) produced by supersonic molecular beam deposition (SMBD). Two different lying down monolayer phases were observed depending on the substrate temperature. At low temperatures a poorly ordered phase was observed, while the diffraction patterns of the film grown at high temperatures were similar to that of mercaptoundecanol (MUD) SAMs reported previously in the literature. The transition from the low temperature phase to the high temperature phase is due to S-S bond cleavage at the surface. Desorption from several different chemisorbed and physisorbed states were observed with energies in the same range as observed for MUD and octadecanelthiol (ODT) SAMs.