Thermally-driven isotope separation across nanoporous graphene

Quantum tunneling contributes to the transmission of atoms through nanoporous graphene barriers, even at room temperature. In a temperature gradient, the mass-dependence of tunneling leads to isotope separation, in contrast to the classical transmission case where no separation can occur. Using transition state theory, we show that zero-point and tunneling contributions enrich the isotopes in opposite directions with respect to the temperature gradient. Zero-point energy differences dominate around room temperature.