ADSORPTION AND FILM FORMATION OF THYMINE ON A GOLD(100) SINGLE-CRYSTAL ELECTRODE

The film formation of thymine adsorbed at a Au (100) surface in aqueous solution has been analysed by means of cyclic voltammetrie and capacity-potential measurements. On the freshly flame annealed and therefore reconstructed (100) surface the formation of a 2-dimensional condensed adlayer of thymine has been observed. On the unreconstructed (100) surface exists no condensed adsorbate state. A certain amount of charge transfer from adsorbed thymine molecules is detected at potentials near to the potential of zero charge. Variation of the pH of the solution reveals a transfer of nominally 0.81 electrons per molecule. From this the surface concentration of chemisorbed thymine at positive potentials is estimated. The surface concentration correlates with an adsorption state in which the molecular plane of thymine is parallel oriented to the surface.