INTERFACIAL PROPERTIES OF URACIL FILMS ADSORBED AT THE MERCURY/ELECTROLYTE INTERFACE

The absorption behavior of uracil at the mercury/electrolyte interface was studied by electrocapillary and capacitance measurements. Three different adsorption states (SI, SII, SIII) can be distinguished, depending on adsorbate concentration, temperature and potential. State I corresponds to a layer of adsorbed uracil molecules oriented flat on the electrode, which exhibits weak lateral interactions. The Frumkin isotherm is applicable. State II exhibits the properties of a 2-D condensed film. Based on a lattice-gas treatment an isotherm corresponding to the "low temperature series expansion" is applied. State III probably results from the formation of a multi-layer.