Potential-assisted deposition of alkanethiols on Au: Controlled preparation of single- and mixed-component SAMs

The commonly used method of preparing RS/Au self-assembled monolayers (SAMs ) involves a passive incubation process in a nonabsorbing solvent. Preparat ion of mixed-component SAMs is particularly problematic under these conditi ons. The time course of the open circuit potential in the passive adsorptio n experiment suggests that control of the deposition potential could lead t o a faster and ultimately more complete SAM formation process. This is show n to be the case, as both C-16 RS/Au SAMs and mixed C-16/HOOCC15S/Au SAMs a re shown to be readily prepared in approximately 15 min from 5 mM thiol sol utions at potentials ranging from 200 to 600 mV (vs Ag/AgCl). The blocking properties of the resulting C16 SAMs are excellent. This technique provides access to mixed-composition SAMs otherwise inaccessible using deposition u nder open circuit conditions.