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

Using the nanosized porous medium SBA-15, we construct the condensed spin-1 network composed of oxygen molecules (O-2) with tube and rod structures. The condensed network can be controlled by changing the amount of O-2 molecules and substituting nonmagnetic nitrogen molecules (N-2) at the O-2 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 T(liq_gas )is 90 K, while in SBA-15 with a pore size of 8.5 nm, the monolayer network of O-2 has a T-liq_gas value of 60 K. However, in the monolayer system, when a half of O-2 site is diluted with N-2, T-liq_gas increases to 94 K. Even after the N-2 molecules are vaporized, they affect the physisorption potential of the inner wall of SBA-15. The resultant electric cloud of N-2 hinders the evaporation of O-2, resulting in an increase in T-liq_gas. The effect is weakened with increasing number of physisorption layers. Thus, this study presents the unique condensation phenomenon of two molecules with different T-liq_gas under a strong physisorption potential.