A model for molecular adsorption on the surface of a columnar structure including steric effects and adsorbate-adsorbate repulsive interactions

Two-dimensional Monte Carlo simulations for adsorption on a columnar struct ured substrate were made to explore the steric effects of pore width and de pth on molecular adsorption under adsorbate-adsorbate repulsive interaction s. Simulation adsorption data fit a Frumkin-type isotherm for each set of p ore width, depth and top column dimensions. As pore depth increases and por e width approaches the adsorbate molecular size, the surface coverage by ad sorbed particles decreases sharply. Therefore, the adsorbate-adsorbate inte raction parameters derived from the simulated isotherms exhibit a marked de pendence on the substrate roughness factor (R). Phenomenologically, the inf luence of R on the isotherms is smoothed down by introducing a correction f actor (f), which allowed us to collapse all simulated isotherms into a sing le isotherm. Results from the model are qualitatively compared to earlier o bservations about the influence of columnar structured gold surface roughne ss on the adsorption of 1,10-phenantroline in acid solution (oph) at consta nt potential (E > E-pzc). (C) 2001 Elsevier Science Ltd. AH rights reserved .