Surface potential studies of self-assembling monolayers using Kelvin probe force microscopy

The local contact potential difference (CPD) of different self-assembled n-alkanethiol monolayers on Au substrates has been measured using Kelvin probe force microscopy (KPFM). Our results demonstrate that KPFM can be used to obtain topography and CPD information simultaneously. The measured CPDs show a clear chemical contrast, allowing us to distinguish between thiol molecules with different terminal groups. The CPD values of the same terminal group are found to vary with chain length, which is explained in the context of the dipole layer model.