Domain structure of binary self-assembled monolayers composed of 3-mercapto-1propanol and 1-tetradecanethiol on Au(1 1 1) prepared by coadsorption

The structure of the domains of phase-separated binary self-assembled monolayers (SAMs) composed of 3-mercapto-1-propanol and 1-tetradecanethiol (TDT) on Au(1 1 1) strongly depends on the thiol concentration of the solution from which the SAM is formed. Cyclic voltammograms and scanning tunneling microscopic images show that a binary SAM formed from 1×10-6 mol dm-3 concentration of a thiol solution exhibits the phase separation with characteristic finger-shaped domains, long and narrow TDTrich domains elongate to <1 0 1> directions of the Au substrate. The size of the domains becomes longer and the degree of phase-separation becomes higher as the concentration of the thiol solution used in preparing the SAM is lower.