The interaction between atomic-scale pores and particles

Using first-principles calculations for angstrom-sized pores (3-10 angstrom), we investigate pore-particle interaction. The translocation energy barrier (TEB) plays important role for the angstrom-scale pores created in 2D-materials such as graphene which is calculated for the translocation of rare gases (He, Ne, Ar, Xe), diatomic molecules (H-2 and N-2), CO2, and CH4. The critical incident angle (the premeance beyond that is zero) was found to be 40 degrees, which is different from classical model's prediction of 19-37 degrees. The calculated TEB (Delta) and the surface diffusion energy barrier (Delta ') for the particles with small kinetic diameter (He, Ne and H-2), show that the direct flow is the dominant permeation mechanism (Delta approximate to 0 and Delta ' > 30 meV). For the other particles with larger kinetic diameters (Ar, Kr, N-2, CH4 and CO2), we found that both surface diffusion and direct flow mechanisms are possible, i.e. Delta and Delta ' not equal 0. This work provides important insights into the gas permeation theory and into the design and development of gas separation and filtration devices.