Phase-separated alkanethiol self-assembled monolayers investigated by non-contact AFM

We investigated phase-separated self-assembled monolayers (SAMs) of alkanethiol molecules on Au(1 1 1) surfaces as model samples which have nanometer-scale domain distribution by non-contact atomic force microscopy (NC-AFM). We made SAMs composed of 1-decanethiol (CH3–(CH2)9–SH; C10) and 1,10-decanedithiol (HS–(CH2)10–SH; C10D). We obtained topographic, surface potential (SP) and energy dissipation images. The obtained topographic images suggested the sample surface was composed of closely packed C10 monolayer domains and C10D domains. The SP of C10 domains were about 100–150 mV higher than that of C10D domains. The energy dissipation on C10D domains were larger than that on C10 domains. We discussed the origins of difference in SP and the dissipated energy on the C10 and C10D domains.