Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 7: Liquids
CPP 7.2: Vortrag
Montag, 23. März 2009, 18:15–18:30, ZEU 160
Cation Dynamics in Ionic Liquids as seen by QuasiElastic Neutron Scattering — •Jan Peter Embs1,2 and Rolf Hempelmann2 — 1Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institut, CH - 5232 Villigen-PSI — 2Physical Chemistry, Saarland University, D-66041 Saarbrücken
Quasi-elastic Neutron Scattering (QENS) is a powerful tool to investigate the dynamics of species containing protons on a picosecond (ps) time and Angstrom length scale. With this method one can investigate crystalline as well as liquid samples. We use QENS to probe the cation dynamics in pyridinium and imidazolium based ionic liquids containing anions that are not visible due to their negligible scattering cross sections. In this contribution we will present data obtained using different time-of-flight (FOCUS@SINQ, TOFTOF@FRM-II) as well as backscattering spectrometers MARS@SINQ, IN10@ILL). Different spectrometers are needed in order to obtain experimental results on different time and spatial scales and thus deepen the insight into the dynamical processes occurring in ionic liquids. Our results show that even in the liquid phase the corresponding cations perform localized motions (translational and rotational jump processes inside confining regions (cages) built up by surrounding ions) together with slower processes that can be attributed to rearrangements of the ions forming the confining cages. Furthermore using QENS we also can get insight into inelastic processes and thus completing the inelastic region that can be probed by far-infrared spectroscopy.