We investigate the structural and diffusive dynamics properties of a model fluid in highly-absorptive cylindrical pores. At subcritical temperatures, self diffusion displays three distinct regimes as a function of average pore density ρ: 1) a decrease in self-diffusivity with increasing ρ at low ρ, 2) constant self-diffusivity with respect to varying ρ at moderate density, and 3) a decrease in self-diffusivity with increasing ρ at high density. These regimes are closely linked to the thermodynamic properties of the fluid in the pore, specifically, the adsorption isotherm, isosteric heat of adsorption, and the density profile. We show that, the three diffusivity regimes qualitatively correpsond to three distinct adsorption regimes: monolayer formation, multilayer adsorption, and pore filling.
Pub Type: Journals
Self-diffusivity, gas adsorption, molecular dynamics, confined fluids, physical properties