Molecular monolayer, electron transfer across

If a defect-free molecular assembly covers an electrode surface completely, the assembly is an efficient electrochemical blocker [23, 30, 46, 47]. Electron transfer through the SAM to a solution redox probe is substantially slower than the rate of diffusion of the probe to the surface, and the voltammetric response is a quasiexponential increase in Faradaic current resulting from electron transfer across the chains of the SAM [30, 46]. This type of response qualitatively supports the presence of a monolayer low in defect sites. A more quantitative measure of the EBE of a modified electrode is expressed as the percentage of total blocking achieved using a bare electrode as the standard [48] ... 

The development of alkanethiolate monolayers on gold as well-characterized, electrode-bound molecular assemblies sets the stage for electron-transfer measurements in more well-defined systems than has previously been available. Chidsey and co-workers began to adapt and test these systems for studying electron transfer across the monolayer [30, 45, 74]. They chose to employ a pendant ferrocene-carboxylate redox probe. Mixed monolayers were formed of the electroactive redox probes diluted with various amounts of methyl-terminated -alkanethiols (Systems... 

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