Chain-length dependence of the structures and phases of ${\mathrm{CH}}_3$(${\mathrm{CH}}_2$${)}_{\mathit{n}\mathrm{-}1}$ SH self-assembled on Au(111)

A grazing incidence x-ray diffraction study of ${\mathrm{CH}}_3$(${\mathrm{CH}}_2$ ${)}_{\mathit{n}\mathrm{-}1}$SH self-assembled on a Au(111) surface shows that self-assembly results in a nonequilibrium state with a specific defect structure. We also explore the global (n,T) phase diagram whose phases are distinguished by the tilt direction and the two-dimensional periodicity. These phases result in distinct long (n>14) and short (n<14) chain-length regimes, and reflect the relative importance of the hydrocarbon and interface interactions in these systems.