Surface Electrochemistry of Amino Acids: Voltammetry Assisted by EELS (Electron Energy-Loss Spectra), Auger and LEED

摘要

Recent studies by means of thin-layer electrochemistry of the chemisorption at polycrystalline Pt of hydroquinone, catechol and more than 50 related compounds have revealed that a layer of oriented molecules is formed in virtually all instances. Variables affecting adsorbate orientation include: adsorbate molecular structure, adsorbate concentration, electrode potential, nature of the electrolyte anion, temperature, solvent and structure of the Pt surface. Adsorbate orientation strongly influences the course of electrocatalytic oxidation and reduction. The present work brings some advances in technique to bear on such studies: well-defined Pt(111) and pt(100) surface were employed as substrates; surface molecular packing densities were measured by means of Auger spectroscopy (rather than by thin-layer voltammetry), thus extending the range of experimentation to include non-electroactive compounds and concentrations outside the range of adsorption measurements with thin-layer electrodes; much useful insight into the nature of the adsorbed species was obtained from electron energy-loss spectra (EELS) of the adsorbed layers. Reprints. (KT)