Relationship between the c(4×2) and the (√3×√3)R30° phases in alkanethiol self-assembled monolayers on Au(111)

Abstract

Transformation between the two well-known phases of alkanethiol monolayers on Au(111), c(4×2) and (√3×√3)R30°, has been studied using scanning tunneling microscopy in ultra-high vacuum. Among the many versions of the c(4×2) phases observed, one particular structure where a lateral shift of adsorbate by as much as 0.17 nm within the unit cell is found. This lateral shift along the [11] direction corresponds to the movement of one adsorbed unit, towards its nearest neighbour from one hollow site to another (fcc to hcp, or hcp to fcc).