Peter J. Branton, Katsumi Kaneko and Kenneth S. W. Sing
Pore filling by oxygen takes place reversibly at 77 K in pores of effective width of ca. 2.6 nm, whereas hysteresis is involved in the filling (by capillary condensation) of wider pores; it appears that the oxygen meniscus becomes unstable at cylindrical pore widths < ca. 2.9 nm.