Domain structure of binary self-assembled monolayers composed of 3-mercapto-1-propanol and 1-tetradecanethiol on Au(111) prepared by coadsorption

The structure of the domains of phase-separated binary self-assembled monol ayers (SAMs) composed of 3-mercapto-1-propanol and 1-tetradecanethiol (TDT) on Au(111) strongly depends on the thiol concentration of the solution fro m which the SAM is formed. Cyclic voltammograms and scanning tunneling micr oscopic images show that a binary SAM formed from 1 x 10(-6) mol dm(-3) con centration of a thiol solution exhibits the phase separation with character istic finger-shaped domains, long and narrow TDT-rich domains elongate to [ 101] 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. (C) 2001 Elsevier Sc ience B.V. All rights reserved.