An interplay of adsorption and corrugation at HCl–ice interfaces

A role of ice corrugation in increasing HCl coverage and adsorption energy E is studied within a simple model, involving a competition between the surface morphology η and coverage θ. It takes into account that the surface steps create new adsorption sites and have a larger binding energy compared to the flat area. Depending on an interplay of the step and the binding energy variations εs, εb the adsorption proceeds in one 0<θ<2 or in two stages 0<θ<1 and 1<θ<2. The latter is supplemented by the adsorbate-induced healing, manifested by the surface flattening at nonzero coverages. A reasonable choice of the parameters allows us to recover the experimental results, obtained for HCl on ice at stratospheric conditions.