ADSORPTION OF NITROGEN ON GRAFOIL PREPLATED WITH CARBON-TETRACHLORIDE AT 77-K

Nitrogen adsorption on Grafoil preplated with carbon tetrachloride has been studied volumetrically at 77 K. The step in the N2 adsorption isotherm which is caused by the order-disorder (solid-fluid) phase transition of adsorbed N2 has been observed for various amounts of CCl4 preadsorbed. The equilibrium pressure of N2 at which the step appears is not affected by the preadsorption of CCl4. The step height decreases linearly with increasing amount of CCl4 preadsorbed, until the step disappears at 0.844 +/- 0.053 monolayer (ML) of CCl4. It is suggested that the adsorbates separate into an essentially pure N2 phase and a phase mixture of CCl4 and N4 when the amount of CCl4 preadsorbed is less than 0.844 ML. It is also found that the amount of N2 which fills the first overlayer of the monolayer CCl4 is comparable to or slightly greater than the 1 ML quantity of CCl4.