Traditionally magnetic resonance is the most common experimental method at E3. It is based on the Zeeman Effect, which is a splitting of spin states of electrons and nucleons under the influence of an external magnetic field. The sample is exposed to a strong static magnetic field (typically 0.1 to 10 T). An oscillating field which is oriented perpendicular to the static field excites transitions between these levels, where the resonance frequency (typically a few Mhz up to 100 Mhz for nuclear spins). There is a broad range of applications for this method and thus it has many applications in physics and chemistry. For the latter it is of tremendous importance, as it allows the analysis of molecular structures and the observation of many transport phenomena. It has also become of interest in medicine, where it is used for non-invasive in vivo examinations. Besides its application for imaging it is also used for spatially resolved in vivo spectroscopy.