ESR = Electron Spin Resonance Spectroscopy

ESR Spectroscopy is a chemico-physical analytical test method which was developed in the 1940th by Jewgeni Konstantinowitsch Sawoiski and is based on the absorption of microwave radiation. The samples are inserted into the ESR-spectrometer, where a magnetic field and a microwave of a specific energy are used to induce the absorption of this energy due to the presence of paramagnetic molecules or ions. A sample with paramagnetic behavior orients itself inside the magnetic field, where the spins of an electron take on different energy levels, and is able to absorb the provided microwave in dependence on the magnetic field. In this way, a characteristic spectrum is acquired.

Due to the extremely short-living time of paramagnetic species in nature, it is common to add paramagnetic molecules, so called spin probes, to the samples under examination and quantify the response of the system. Depending on its chemical structure and environment, it absorbs certain energies and gives rise to so-called ESR absorption spectra.

In this way we can label the structures under examination with paramagnetic molecules, which insert themselves into the systems under examination like membranes, aggregates and structures with a chemico-physical order. It is also possible to generate free-radical reactions in all kinds of samples.


We are using radical-initiators like UV-light, certain pollutants, Xanthine/xanthine oxidase or Superoxide dismutase systems and generate hydroxyl and superoxide radicals directly inside the sample or in ex vivo tests. Also, there are some metal ions having paramagnetic attributes (for instance copper(II)+ or magnesium) which yields strong ESR patterns and can be used to characterize the structure and organization of a sample.

The samples under investigation can be very diverse, since the ESR allows to investigate solid, liquid and gaseous samples. We use a variety of solvents, inhomogeneous matrices, and human or animal skin and hair samples to characterize the structure, organization and chemical reactivity.

The ESR Spectroscopy is the basis of all our methods, which you can find a detailed description for in the methods navigation list.