Physical adsorption on flat and corrugated surfaces

by 1976- Trasca, Raluca Andreea

iii Theoretical methods such as virial expansion, mean field theory and Monte Carlo simulations are employed to investigate adsorption of gases on various surfaces. For complex substrates like quasicrystalline structures, a virial expansion approach provides adsorption isobars and isosteric heats which are compared to experimental data in the limit of low coverage. In the case of flat or weakly corrugated substrates, a two dimensional approximation of the virial expansion is used instead. Adsorption inside cylindrical pores, as found in carbon nanotube bundles, is explored with a lattice gas model evaluated with mean field and Monte Carlo techniques in both grand canonical and canonical ensembles. The phonon spectrum of a monolayer film adsorbed on the wall of a spherical surface is calculated and compared to that of a cylindrical film. A special attention in this thesis is dedicated to the effective dimensionality experienced by the adsorbate, which leads to new and interesting effects.