ADSORPTION-ISOTHERM STUDY OF MONOLAYER FILMS OF N-2 ON BN

We have measured adsorption isotherms for N-2 films on BN for temperat ures between 51 and 75 K and coverages in the first layer. Data measur ed below 65.8 K display two features: a substep and (at slightly highe r coverages) a kink in the slope of the isotherm. Isotherms measured a t and above 65.8 K have no features present in them. The isotherm and isothermal compressibility data for N-2 On BN are compared with very s imilar corresponding data for Kr, CO, and N-2 on graphite; this compar ison is used to propose an interpretation for the observed features of N-2 On BN. Our results for N-2 are also contrasted with data for Kr o n BN; the differences observed between these two systems are discussed .