ABSTRACT
This chapter deals with the dependence of spin-label EPR spectra on environmental polarity and proticity. Isotropic and anisotropic hyperfine couplings, isotropic g-values and gxx (to a lesser extent gyy ) g-tensor elements and also14N-quadrupole interactions depend on polarity, i.e., on dielectric constant. All these spin-Hamiltonian parameters are perturbed more strongly by hydrogen bonding to the nitroxide oxygen than they are by polarity. A valuable summary is given in the concluding section of this chapter.
