The EMR-group studies the microscopic structure of paramagnetic point defects in solids by means of Electron Magnetic Resonance (EMR) Spectroscopy. The research is mainly focused on irradiation damage of organic crystals (sugars, amino-acids, etc.), apatites, transition-metal or lanthanide activated optical materials (phosphors) and semiconductors.

EMR (Electron Magnetic Resonance) is the electronic counterpart of NMR (Nuclear Magnetic Resonance). This form of spectroscopy can detect and identify atomic or molecular systems with unpaired electrons (paramagnetic centra). EMR spectroscopy conventionally uses ESR (Electron Spin Resonance) also known as EPR (Electron paramagnetic resonance), but this is often extended using other techniques as ENDOR (Electron Nuclear Double Resonance) and EI-EPR (ENDOR-induced EPR). By means of ENDOR one can observe NMR transitions via the change in the EPR-signal, this results in a higher sensitivity than NMR.

EMR is well known for his unambiguous and detailed characterisation of paramagnetic centra (symmetry, electron spin, valence, chemical identity, electronic and geometric structure of the interacting surroundings, etc.), but can also benefit of his high sensitivity (aprox. 10¹⁰ paramagnetic centra as absolute value) and his non-destructive character. The latter is a main advantage for the application of EMR in radiation dosimetry, dating and the detection of irradiation food for conservation.

As for NMR, EMR is based on the presence of an (electronic) magnetic moment that interacts with the internal (ex. originating from surrounding nuclear spins) and applied magnetic field. EMR-signals represent the observation of a magnetic dipole transition between electronic levels, which are splitted by means of Zeeman- and/or hyperfine interactions. Those transitions are induced by the absorption of microwaves. The wavelength of these microwaves depends on the type of spectrometer.

EMR is applicable on a broad range of fields for example biology, chemistry, physics, geology, medicine, pharmacy, materials sciences and agriculture. Although in our department EMR is mainly used for the study of defects and radicals in solids, liquids and gases can also be measured.

The EMR-group has EPR, ENDOR and EI-EPR in X- and Q-band (microwave with frequencies of 9.5 GHz and 34GHz respectively), extended with cryostats having the possibility for in-situ illumination.