AVS 50th International Symposium
    Surface Science Thursday Sessions
       Session SS+OM-ThA

Paper SS+OM-ThA2
Spectroelectrochemical Studies of Self-Assembled Monolayers of Thiols

Thursday, November 6, 2003, 2:20 pm, Room 327

Session: Self-Assembled Monolayers
Presenter: I. Thom, St Andrews University, Scotland
Authors: I. Thom, St Andrews University, Scotland
M. Buck, St Andrews University, Scotland
Correspondent: Click to Email
Thiol SAMs provide a convenient route to modify electrodes and to serve as templates for directing electrochemical processes. Towards a rational design of thiol SAMs for electrochemical applications the electrochemically induced desorption and adsorption of thiols are studied in-situ using the combination of electrochemistry and non-linear optical techniques. Potential dependent capacitive and faradaic currents are correlated with the second harmonic signal which probes the S-Au bond formation. Studies of alkane thiols and biphenyl based thiols reveal that this correlation is strongly dependent on the electrolyte, i.e. both the penetration of ions into the layer and the desorption mechanism are affected by the electrolyte. In the ethanol case, a change in the desorption mechanism during multiple potential cycling is observed. While the current continuously decreases with increasing number of cycles, the change of the SHG signal remains essentially unaltered and indicates a change in the faradaic process. This change is explained by a transition from thiolate to disulfide formation upon the desorption of thiols.