Collective ion diffusion and localized single particle dynamics in pyridinium-based ionic liquids

J Phys Chem B. 2014 Dec 11;118(49):14452-60. doi: 10.1021/jp5092416. Epub 2014 Nov 25.

Abstract

Quasielastic neutron scattering with polarized neutrons allows for an experimental separation of single-particle and collective processes, as contained in the incoherent and coherent scattering contributions. This technique was used to investigate the dynamical processes in the pyridinium-based ionic liquid 1-butylpyridinium bis(trifluoromethylsulfonyl)-imide. We observed two diffusion processes with different time scales. The slower diffusional process was present in both the coherent and the incoherent contribution, meaning that this process has at least a partial collective nature. The second faster localized process is only present in the incoherent scattering contribution. We conclude that it is a true single-particle process on a shorter time scale.