ANISOTROPY IN PHYSICAL ADSORPTION ON GRAPHITE.
Abstract
Anisotropy of polarizability has been taken into account in calculating the relative strengths of adsorption of Ne, A, Kr, Xe, and CO2 on several possible sites in the graphite lattice. A 6-12 potential, modified to include an angular dependence arising from anisotropy considerations, was summed over the lattice. As a direct result of the anisotropy, sites on the plane consisting of edges of basal planes exhibit a higher energy of adsorption at 0 K for all the gases considered. Calculations ignoring anisotropy have shown that the nature of the results depends markedly on this characteristic of graphite. For the inert gases at -196 C, adsorption is still favored on the edge plane unless the adsorption is considered to be immobile. In contrast, for CO2 at 0 C entropy effect predominates and the basal plane offers the more favorable sites for adsorption. These calculations have ignored any unusual edge effects which may overwhelm the anisotropy effects; in the absence of such effects anisotropy is able to account for the existence of two types of sites on graphite, the relative stability of which depends on temperature. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 31, 1967
- Accession Number
- AD0660378
Entities
People
- Edwin F. Meyer
Organizations
- United States Naval Research Laboratory