DOUBLE-LAYER EFFECTS AT MOLECULAR FILMS CONTAINING ACID-BASE GROUPS

The effect of the double layer on the ionization of acidic head groups in a self-assembled monolayer on a gold electrode is considered. A mo del is developed which assumes that the head group is located in a reg ion of low dielectric constant adjacent to the oillike monolayer. Expr essions are developed for the potential distribution in the interface and its differential capacity. It is emphasized that discreteness-of-c harge plays an important role in determining the local potential at th e ionizable head group. The results obtained are discussed with respec t to other models and experimental data presented recently in the lite rature.