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

Vapor-pressure isotherms of N-2 on BN were measured at 17 temperatures in the vicinity of the bulk triple point to study the behavior of the multilayer physisorbed films. Four steps were resolved in the adsorpt ion data. The fourth step exhibits a region of high-temperature reshar pening between 58 and 62 K. The third step also exhibits a region of h igh-temperature resharpening (between 62 and 65 K). The resharpened th ird steps, however, are not as sharp as their lower-temperature counte rparts. The critical layering temperatures for the second, third, and fourth layers were determined. The N-2 data are compared to data for t he same and other adsorbates on graphite, as well as to theoretical ex planations for the existence of a region of high-temperature step resh arpening.