HARD-RODS ON A LINE AS A MODEL FOR ADSORPTION OF GAS-MIXTURES ON HOMOGENEOUS AND HETEROGENEOUS SURFACES

It is shown that a mixture of hard rods on aline in a homogeneous exte rnal field is ideal. The composition of such an adsorbed mixture is de termined not by the relative values of the energies of the adsorbed mo lecules but by the relative values of a function similar to the enthal py of a single molecule. In contrast, the hard rod mixture in an inhom ogeneous external field is not ideal but displays minor negative devia tions from Raoult's law. It is suggested that the deviation from ideal ity depends significantly upon the dimensionality of the space.