Isotope Effect on Adsorbed Quantum Phases: Diffusion of H2 and D2 in Nanoporous Carbon.

Quasielastic neutron scattering of H2 and D2 in the same nanoporous carbon at 10-40 K demonstrates extreme quantum sieving, with D2 diffusing up to 76 times faster. D2 also shows liquidlike diffusion while H2 exhibits Chudley-Elliott jump diffusion, evidence of their different relationships with the local lattice of adsorption sites due to quantum effects on intermolecular interactions. The onset of diffusion occurs at 22-25 K for H2and 10-13 K for D2. At these temperatures, H2 and D2 have identical thermal de Broglie wavelengths that correlate with the dominant pore size. [ABSTRACT FROM AUTHOR]