Modified statistical treatment of partially mobile adsorbates

Abstract

A simple statistical treatment is given for partially, patchwise mobile adsorbates. For monolayers of monatomic molecules, neglecting lateral interaction but allowing for finite size, a gradual transition from the Langmuir isotherm to the Volmer isotherm is obtained if the mobile fraction of the adsorbate increases or if the temperature is increased. The distribution of the adsorbed molecules over the mobile and localized part of the surface is also computed. At low coverage, a great preference for the mobile part is found, but if saturation is approached there is some preference for accommodation in the localized part.