The Umbella high-frequency EPR facility

The Umbella high-Frequency electron paramagnetic resonance (EPR) facility i s a part of the Nijmegen High Field Magnet Laboratory with spacial emphasis on multifrequency EPR For chemical and biological applications. At present the facility has various solid-state sources available for the frequency r ange between 95 and 400 GHz, combined with magnetic fields up to 30 T. For frequencies above 400 GHz a Far-infrared laser is used. With superheterodyn e detection techniques a typical dynamical range of 130 dB is obtained, wit h single-mode resonators, oversized cylindrical and Fabry-Perot resonators. Some examples will be shown to demonstrate the power of multifrequency EPR in high-spin systems.