NEW MONOLAYER PHASES OF N-ALKANE THIOLS SELF-ASSEMBLED ON AU(111) - PREPARATION, SURFACE CHARACTERIZATION, AND IMAGING

We report the observation by scanning tunneling microscopy (STM) and low energy atom diffraction, of new, striped, structures at the surface of monolayers of n-alkane thiols [CH3 (CH2)n - 1 SH with n = 8,10,12] self-assembled on the (111) face of single crystal gold. These structures can be prepared by slow (room temperature) or thermally accelerated treatment of the well known c(4√3×2√3)R 30° phase formed by self-assembly in solution, or can be accessed directly by molecular beam deposition. With respect to the unit mesh of the gold substrate, the new striped structures can be described as p × √3 overlayers where 7.5≤p≤13. The discovery of these phases has implications for the understanding of the growth mechanisms and the pursuit of applications of this widely studied class of materials. © 1994 American Institute of Physics.