ESR spectra and structure of inorganic fluorine-containing free radicals

The article is concerned with the paramagnetic fluorides of Groups III-VII elements, and is restricted to ESR spectra in the condensed phases. The analysis of ESR spectra showing large hyperfine splittings presents a number of difficulties. The underlying problem in cases of a strong interaction between the electron and nuclear spins is that of an incomplete Paschen-Back effect: the Hamiltonian is not even approximately diagonal in the high-field, uncoupled representation and the usual first-order solution, which ignores off-diagonal terms, is incorrect. Further discussion is restricted to the isotropic case; the analysis of anisotropic spectra is similar, although more complicated, and has been adequately treated elsewhere. 45 references, 6 figures, 7 tables