Adsorption of nitrogen on grafoil preplated with carbon tetrachloride at 77 K

Abstract Nitrogen adsorption on Grafoil preplated with carbon tetrachloride has been studied volumetrically at 77 K. The step in the N 2 adsorption isotherm which is caused by the order-disorder (solid-fluid) phase transition of adsorbed N 2 has been observed for various amounts of CCl 4 preadsorbed. The equilibrium pressure of N 2 at which the step appears is not affected by the preadsorption of CCl 4 . The step height decreases linearly with increasing amount of CCl 4 preadsorbed, until the step disappears at 0.844 ± 0.053 monolayer (ML) of CCl 4 . It is suggested that the adsorbates separate into an essentially pure N 2 phase and a phase mixture of CCl 4 and N 4 when the amount of CCl 4 preadsorbed is less than 0.844 ML. It is also found that the amount of N 2 which fills the first overlayer of the monolayer CCl 4 is comparable to or slightly greater than the 1 ML quantity of CCl 4 .