Adsorption Studies on the Mechanism of Ice Nucleation: I. Oxide Nuclei

The adsorption of water vapor was measured at several constant temperatures from 0°to -15°C on the oxides of zinc, cadmium, nickel and copper by weighing method. The isotherms obtained are all of the sigmoid nature, but with some step-wise discontinuities. The heats of adsorption were calculated from the isotherms, those of the first to second layer being found higher than those of next few layers which approached the heat of condensation of water vapor. The data have been discussed in terms of two-dimensional transitions of state, taking into consideration the interaction effects between adsorbed water olecules together with the adsorption forces of the solid surface toward the layers of adsorbed water molecules.