Condensation phenomenon of oxygen and nitrogen molecules physisorbed into a porous medium

Abstract

Using the nanosized porous medium SBA-15, we construct the condensed spin-1 network composed of oxygen molecules (O2) with tube and rod structures. The condensed network can be controlled by changing the amount of O2 molecules and substituting nonmagnetic nitrogen molecules (N2) at the O2 site. The characteristics of the two-dimensional spin model were observed in the monolayer and double layer physisorption systems. In a typical bulk system, the liquidizing temperature Tliq−gas is 90 K, while in SBA-15 with a pore size of 8.5 nm, the monolayer network of O2 has a Tliq−gas value of 60 K. However, in the monolayer system, when a half of O2 site is diluted with N2, Tliq−gas increases to 94 K. Even after the N2 molecules are vaporized, they affect the physisorption potential of the inner wall of SBA-15. The resultant electric cloud of N2 hinders the evaporation of O2, resulting in an increase in Tliq−gas. The effect is weakened with increasing number of physisorption layers. Thus, this study presents the unique condensation phenomenon of two molecules with different Tliq−gas under a strong physisorption potential.