One- and two-dimensional pulse electron paramagnetic resonance spectroscopy: concepts and applications

During the last two decades, the possibilities of pulse electron paramagnet ic resonance (EPR) and pulse electron nuclear double resonance (ENDOR) spec troscopy have increased tremendously. While at the beginning of the 1980s p ulse-EPR and ENDOR applications were still a rarity, the techniques are now very frequently applied in chemistry, physics, materials science, biology and mineralogy. This is mainly due to the considerable efforts invested in the last few years on instrument development and pulse-sequence design. Pul se-EPR spectrometers are now commercially available, which enables many res earch groups to use these techniques. In this work, an overview of state-of -the-art pulse EPR and ENDOR spectroscopy is given. The rapid expansion of the field, however, does not allow us to give an exhaustive record of all t he pulse methods introduced so far. After a brief and very qualitative desc ription of the basic principles of pulse EPR, we discuss some of the experi ments in more detail and illustrate the potential of the methods with a num ber of selected applications.