ABSTRACT
In this and the next two chapters we will develop some of the quantum mechanical background of EPR spectroscopy collectively known as the spin-Hamiltonian theory, and we will particularly be interested in specific adjustments, be they extensions or simplifications, that make the theory applicable to biomolecules. Although the theory is only a small subset of quantum mechanics in general, its understanding and subsequent application does require some proficiency in mathematics, notably regarding complex numbers and matrix algebra, and in the physics’ view of wave equations and operators. Here, in contrast to our approach in previous chapters, very little will come “out of the blue”; effort has been put into assuring that each step made follows understandably from what preceded it and is amply illustrated by fully worked out examples. Having mastered the three chapters that make up Part 2 you will have acquired a profound understanding of EPR powder patterns of randomly oriented paramagnets, and you will be prepared to tackle just about any problem in continuous-wave biomolecular EPR spectroscopy. If, however, you decide now or during your reading of these three theoretical chapters that Part 2 is “a bridge too far,” then simply skip it in the knowledge that many significant bioEPR experiments with chemical, biological, and/or medical bearing can be carried out with the background thus far provided in the previous chapters. Do, however, read on a little further into the next few paragraphs, which are intended to be a qualitative substitute and summary of the hard-core stuff later in Chapters 7−9.
