The feasibility of in-situ Mössbauer transmission spectroscopy of species adsorbed on high surface area electrodes has been demonstrated using iron phthalocyanine on high surface area carbon. The choice of an appropriate cell geometry has allowed detection of strong absorption signals at room temperature without resorting to isotope enrichment of the compound. The quadrupole splitting of the doublet assigned to FePc adsorbed on the carbon surface was found to decrease from 0.88 mm/s for the dry specimen to 0.68 mm/s upon immersion of the sample into an arsaline electrolyte with a nearly constant isomer shift of ∼0.35 mm/s with respect to α-Fe (metal). This phenomenon is antributed to the formation of an octahedral complex with a hydroxyl ion coordinated in the axial position. Mössbauer spectra at several potentials have been obtained and no significant differences were observed in any of the relevant parameters.
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