Abstract

We present nonlinear light scattering measurements of the equilibrium, multilayer adsorption of molecular species on polycrystalline, porous ice films. The adsorption spectra are quantitatively modeled with the multilayer physical adsorption theory of Brunauer, Emmett and Teller (BET) and an extension based on the Bragg-Williams (BW) formalism which incorporates adsorbate-adsorbate interactions within the first layer. Although the polycrystalline, heterogeneous ice surfaces are likely characterized by adsorption site distributions broad both in energy and the size of local, homogeneous domains, these simple parameterizations model the data to high precision and imply a reduction in the effective complexity of the interface. The ability to quantitatively model adsorption onto a topologically complex, heterogeneous substrate from first principles renders many important systems amenable to quantitative study. For example, we have shown recently [1] that the physical adsorption of H₂O as islands on model polar stratospheric ice surfaces may be a controlling factor in the rates of some surface mediated chemical reactions important in seasonal ozone depletion.

© 1996 Optical Society of America