Journal of Vacuum Science & Technology B, Vol.14, No.2, 1453-1460, 1996
Butanethiol Self-Assembly on Au(001) - The 1X4 Au Missing-Row, C(2X8) Molecular Lattice
We have characterized the molecular packing structure of butanethiol self-assembled monolayers (SAMs) on Au(001) using an ultrahigh vacuum scanning tunneling microscope. Butanethiol SAMs were formed on the clean surface using two different protocols : deposition by gas-phase transport and deposition from ethanol solution. The SAM growth proceeds by nucleation and growth of compact, anisotropic islands. The island growth results in relaxation of the compressed Au(001)(5 x 20) reconstruction with concomitant ejection of excess Au atoms onto the terraces. Although the reconstructed surface contains 0.26 monolayer excess Au atoms, 0.4 monolayer is ejected. The surface Au atoms arrange to form identical 1 x 4 missing row structures on both the original terrace level and the nascent island level. The thiols pack in a commensurate, distorted-hexagonal overlayer on this (1 x 4) missing row structure forming a c(2 x 8) molecular lattice.
Keywords:SCANNING-TUNNELING-MICROSCOPY;RAY PHOTOELECTRON-SPECTROSCOPY;RECONSTRUCTED AU(100) SURFACE;MEDIATED ELECTRON-TRANSFER;OXIDIZED ALUMINUM SURFACE;NORMAL-ALKANOIC ACIDS;STRUCTURAL CHARACTERIZATION;MONOLAYER FILMS;SCATTERING MEASUREMENTS;ORGANOSULFUR COMPOUNDS