Comparing the dynamical heterogeneities in binary glass formers and in a glass former embedded in a zeolite – a 2H NMR study

Abstract We characterize the nature of the dynamical heterogeneities of the small component in a binary glass former and of a glass former confined in a zeolite matrix by applying 2D 2H NMR. In both cases the dynamics are described by a distribution of reorientation correlation times G(lnτ) which is significantly broader compared to that of the corresponding neat system. For the binary system, the 2D NMR spectra clearly reveal exchange processes within G(lnτ), i.e. the dynamical heterogeneities are transient. It is assumed that these exchange processes are caused by translational hopping in an essentially rigid matrix. In the case of the glass former in the zeolite no evidence for exchange processes within G(lnτ) is found by NMR spectroscopy.