Diffusion of benzene confined in the oriented nanochannels of chrysotile asbestos fibers

We used quasielastic neutron scattering to study the dynamics of benzene that completely fills the nanochannels of chrysotile asbestos fibers with a characteristic diameter of about 5nm. The macroscopical alignment of the nanochannels in fibers provided an interesting opportunity to study anisotropy of the dynamics of confined benzene by means of collecting the data with the scattering vector either parallel or perpendicular to the fibers axes. The translational diffusive motion of benzene molecules was found to be isotropic. While bulk benzene freezes at 278.5K, we observed the translational dynamics of the supercooled confined benzene on the time scale of hundreds of picoseconds even below 200K, until at about 160K its dynamics becomes too slow for the μeV resolution of the neutron backscattering spectrometer. The residence time between jumps for the benzene molecules measured in the temperature range of 260Kto320K demonstrated low activation energy of 2.8kJ.