ADSORPTION OF 1,3-DIMETHYLURACIL AT THE AU(111) AQUEOUS ELECTROLYTE INTERFACE - A CHRONOCOULOMETRIC STUDY/

The interfacial behavior of 1,3-dimethyluracil (1,3-DMU) on Au(111) ha s been investigated quantitatively using chronocoulometry. The adsorpt ion parameters such as film pressure, relative Gibbs surface excess, G ibbs energy of adsorption, and electrosorption valency were determined as a function of electrode potential and charge density for concentra tions of 1,3-DMU up to 50 mM. The values of the relative Gibbs surface excess and the small shift of the zero charge potential due to 1,3-DM U adsorption, E(NI), indicate that the organic molecules are oriented parallel to the electrode surface within the entire region of an ideal polarizable interface. The Gibbs energy at maximum adsorption is equa l to -35.4 kJ mol(-1) and suggests weak chemisorption. The strategy of analyzing chronocoulometric data, as shown in the present communicati on, provides the tools for a subsequent project aimed to address the r ole of the adsorbate structure on the thermodynamics of adsorption and phase-formation of N- and C-alkylated uracil derivatives on single cr ystal electrodes.