Accelerated Diffusion of Long-Chain Alkanes between Nanosized Cavities

An anomalous transport effect has been found by neutron spin echo measurements on n‐alkanes diffusing in a small‐pore zeolite: the diffusivity decreases from C1 to C8, but rises for C10 and has a maximum at C12, then decreases again. This confirms the existence of the “window effect” proposed thirty years ago by Gorring. The picture shows schematically how one end of a C12 chain extends through a zeolite window, lowering the barrier to diffusion.