| AVS 54th International Symposium | |
| Surface Science | Wednesday Sessions |
| Session SS2+EM+TF-WeM |
| Session: | SAMs and Organic Films I |
| Presenter: | H.M. Saavedra, The Pennsylvania State University |
| Authors: | H.M. Saavedra, The Pennsylvania State University T.J. Mullen, The Pennsylvania State University C.M. Barbu, The Pennsylvania State University A.A. Dameron, University of Colorado V.H. Crespi, The Pennsylvania State University P.S. Weiss, The Pennsylvania State University |
| Correspondent: | Click to Email |
We have investigated the solution-phase displacement kinetics of 1-adamantanethiolate self-assembled monolayers on Au{111} by n-dodecanethiol molecules using infrared spectroscopy, scanning tunneling microscopy, x-ray photoelectron spectroscopy and electrochemical desorption. The displacement reaction can be described by the fast insertion of n-dodecanethiolate at defects in the original 1-adamantanethiolate monolayer, which nucleates island growth and is followed by eventual slow ordering of the n-dodecanethiolate domains. Langmuir-based kinetics, which describe alkanethiolate adsorption on bare Au{111}, fail to describe this displacement reaction. Instead, a Johnson-Mehl-Avrami-Kolmogorov model of perimeter-dependent island growth yields good agreement with kinetic data obtained over a hundred-fold variation in n-dodecanethiol concentration. Analysis on a model-free basis suggests that displacement is a scale-free process within this concentration regime. The crucial role of the adsorbate lattice, along with the thermodynamic driving forces, rationalizes the rapid and complete displacement of 1-adamantanethiolate monolayers and explains why other monolayers reach kinetic traps that result in slow and incomplete displacement.