Properties of helium isotopes adsorbed on uniform surfaces. I. Isolated atoms

Abstract

Experimental data are reported for the submonolayer adsorption of ⁴He and ³He on the basal plane of a graphitized carbon black and on this substrate after coating with one monolayer of solidified xenon. The results obtained for these four systems include heats of adsorption as a function of coverage, Henry’s law constants, and derived properties of an isolated atom interacting with the solid, such as the average energy, the Slater sum, and the nonconfigurational entropy. Theoretical calculations of the gas–solid potential energy surfaces are reported and compared with previous calculations. The eigenstates for ⁴He and ³He that have been obtained by other workers for these systems were then used in direct theoretical calculations of the experimental quantities. Comparison of theory and experiment is used to comment upon the choice of parameters in the calculated gas–solid potentials for these systems.