The dynamics of cations in pyridinium-based ionic liquids by means of quasielastic- and inelastic neutron scattering

Neutron scattering is an excellent tool to study the dynamics of hydrogen-rich materials. In the present work we subsume our results on pyridinium-based ionic liquids. We have performed inelastic, quasielastic and elastic. Neutron scattering is an excellent tool to study the dynamics of hydrogen-rich materials. In the present work we subsume our work on pyridinium-based ionic liquids. We have performed inelastic, quasielastic and elastic neutron scattering experiments aiming to understand the different dynamical processes that occur at different temperatures in ionic liquids. Using quasielastic scattering we obtained data that can be described as a superposition of localized dynamical processes and long range diffusion. The localized processes, which originate from the alkyl chain and the pyridinium ring of the cation, have been modelled in terms of the so-called Gaussian model. The influence of the length of the alkyl chain, attached to the cation, on the dynamical processes is discussed in detail. Furthermore we show neutron backscattering data, obtained on partially deuterated samples, that clearly demonstrate the melting of the alkyl chain and the activation of methyl end-group rotations at low temperatures. Finally, the power of deuterium labelling is evidenced for inelastic neutron scattering data. (C) 2014 Elsevier B.V. All rights reserved.