Hyperfine interactions nitroxide magnetic tensors

The most significant are the Zeeman (g tensor) and nitrogen hyperfine interactions. These depend somewhat on chemical structure, solvent polarity, and temperature. An assumption has been made almost universally that magnetic parameters that are found in frozen solutions may be used to describe liquid phase spectra. This assumption should be recognized and considered carefully in precise work. It may be invalid for several reasons, including (1) altered distribution of nitroxide molecular conformations,... 

Intramolecular magnetic interactions in nitroxides are (1) the nitrogen hyperfine tensor (2) the g tensor (3) methyl proton hyperfine tensors (4) other proton hyperfine tensors (S) the nitrogen quadrupole coupling and (6) couplings to trace isotopes, mostly One desires to know how these properties depend on solvent and... 

For nitroxides in dilute liquid solution, the generally anisotropic spin Hamilton operator is simplified tremendously and, if imresolved proton hyperfine couplings are treated as line broadening, only the electron-Zeeman interaction and the hyperfine coupling to the magnetic nucleus (7 = 1) remain [20]. The g- and hyperfine (4-) tensors are averaged to isotropic values due to fast motion of the spin probe and the resonance condition for the irradiated microwave becomes... 

In nitroxide free radicals characterized by a hyperfine tensor. A, and g-tensor, g, the interaction between the magnetic moment of an unpaired electron and the magnetic moment of nitrogen nucleus is highly anisotropic. The anisotropy determines the line shape of electron spin resonance (ESR) spectrum of completely immobilized nitrox-ides (Fig. 1), and can be completely averaged out for fast thermal Brownian rotational diffusion in low-viscous media. For the " N nucleus with 7=1 and no other interacting nuclei in the nitroxide, three equidistant lines of equal intensities and widths should be observed in ESR spectra in such media. In fact, even in media of... 

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