Effects of Electrolyte and Potential on the in Situ Structure of Alkanethiol Self-Assembled Monolayers on Silver

Surface Raman spectroscopy using an emersion approach has been utilized to study the effects of electrolyte and applied potential on the in situ structure and conformational order of self-assembled monolayers (SAMs)formed from n-alkanethiols on smooth Ag surfaces. Vibrational information in the v(C-S), v(C-C), d(C-H), and v(C-H) regions is particularly useful in elucidating the degree of order and presence of defects in the monolayer before and after exposure of the SAM to electrolyte and potential. Spectral results from these studies suggest that aqueous 0.1 M electrolytes (NaF, NaCI, NaSCN, NaOH, H₂SO₄) and potential have different effects on the order of the SAMs studied. The order of short chain alkanethiol SAMs is more easily affected by electrolyte and potential than that of the longer chain SAMs.