Mobility of the alkanethiol-gold (111) interface studied by scanning probe microscopy

Scanning tunneling microscopy (STM) was used to observe the motion of pits on the CH3(CH2)nSH/Au(111) surface (n = 5, 15, and 17). These pits are shown to diffuse to step edges at rates independent of the alkanethiol chain length during STM imaging. Heating the CH3(CH2)nSH/Au(111) surface (n = 15 and 17) at 100 °C causes removal of the pits from the surface without damage to the monolayer. The proposed mechanism for pit motion suggests that the Au-S bonds are labile and that only Au atoms diffuse. The pits are shown to be defects in the Au(111) surface formed during thiol adsorption.