Further insights in the internal dynamics can be gained – as long as the molecular units have a dipole moment – by the frequency- and temperature-dependent measurement of a complex dielectric function. The relaxation dynamic of soft matter – such as polymer materials and glassy liquids – are characterized by an enormously wide frequency range. Dielectric or impedance spectroscopy covers this area. It is based on the interaction of an external electrical field with an electrical dipole moment of the sample. Due to the fluctuation-dissipation theorem, the measured susceptibility is linked to the fluctuations of the local polarization, originating from the dynamics on a molecular scale. Neutron scattering is more limited with regard to frequency range, but provides a spatial resolution which is not possible to acquire using dielectric spectroscopy, so that both methods together give a more complete picture.
We have two instruments, one offering a frequency range of up to 10 MHz and the other up to 1.8 GHz.