Surface Stress, Kinetics, and Structure of Alkanethiol Self-Assembled Monolayers
Abstract
The surface stress induced during the formation of alkanethiol self-assembled monolayers (SAM) on gold from the vapor phase was measured using a micromechanical cantilever-based sensor. In situ, real-time monolayer thickness measurements were simultaneously carried out using ellipsometry. Ex-situ scanning tunneling microscopy (STM) was performed in air to ascertain the final monolayer structure. The evolution of the surface stress induced during coverage-dependent structural phase transitions reveals features not apparent in average thickness measurements. These results show that both the kinetics of SAM formation and the resulting SAM structure are strongly influenced by both the surface structure of the underlying gold substrate and by the diffusion rate of the alkanethiol towards the gold surface. In particular, the adsorption onto gold surfaces having relatively large, flat grains produces high quality self-assembled monolayers inducing a large surface stress. In contrast, SAM growth on smaller-grained gold is hindered and results in a much smaller surface stress.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARA33008G