| Abstract
| - Using electrochemical and chemical probes, we demonstrate that thin films of crystalline polymethylene(PM), formed via solution decomposition of diazomethane on gold surfaces, exist in the form of a heterogeneousdistribution with microscopically small pores at low average PM coverages. For evaporated gold substrates,as the PM loading increases above ∼0.8 μg·cm-2, a mass density equivalent to an ∼7 nm thick, fully denseplanar film, a transition from a micropore to a blocked electrode occurs. This microstructural picture isconfirmed by the ability to backfill open areas with alkanethiolates and electropolymerized aniline. Parallelexperiments on sputter-deposited gold films show that the blocking threshold occurs at much lower averagePM coverages and alkanethiolate chemisorption data suggest that the open pores are approaching thesizes of individual molecules. These results can be rationalized by a more uniform nucleation of PMnanocrystals across sputter-deposited relative to evaporated surfaces. This ability to regulate the conformaldeposition of an inert, low dielectric material at the nanometer scale on gold surfaces offers a new wayto engineer electrodes with controlled, micropore dielectric barrier structures and “quasi-two-dimensional”nanocomposite films.
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