Dielectric and optical Kerr-effect spectroscopy into the dynamics of ionic liquids

The proposed project aims at understanding the cooperative and molecular dynamics of roomtemperature ionic liquids (RTILs) on the femto- to nanosecond timescale. For this purpose precise dielectric relaxation (DR) data will be recorded as a function of temperature (∼0 – 80 °C) over the exceptionally wide frequency range of ∼10MHz to 15 THz (3×10−4 −5×102 cm−1), which encompasses all relevant modes associated with molecular reorientations and librations, as well as fast translational motions. Simultaneously, in collaboration with Prof. Wynne (Strathclyde Univ.) low-frequency Raman spectra will be determined for these RTILs in the same frequency range via the ultrafast optical Kerr effect (OKE). As previously shown by us, the complementarity of both spectroscopies yields considerable insights into the molecular-level processes of liquids. Where possible, results obtained in our studies will be compared with data collected for the same RTILs with other techniques within the framework of SPP 1191. These include inelastic neutron scattering (R. Hempelmann), infrared spectroscopy (R. Ludwig), molecular dynamics simulations (R. Ludwig, C. Holm) and quantum-chemical methods (B. Kirchner).