ELECTRON-TUNNELING THROUGH DIFFERENT-THICKNESS ORGANIC FILMS ADSORBEDON ELECTRODES

Using the dicarbollyl iron reduction reaction as an example, we studie d the probability of electron tunnelling through organic films of diff erent thickness, adsorbed on an amalgamated platinum electrode. The fi lm thickness varied from 2 nm (for cetyl alcohol) to 2.2, 2.7, and 3.7 nm for a monolayer of stearic, behenic, and triacontanoic acid, respe ctively. The retardation of the electrode reaction, even by a layer 2. 7 nm thick, appeared to be too small to make the reaction irreversible . Only with the triacontanoic acid film (3.7 nm), did we find a clear- cut effect of the reaction rate decrease. It has been speculated that the electron transfer in the system under discussion proceeded by a su per-exchange mechanism.