Comment on g‐Shifts in the Electron Paramagnetic Resonance of F‐Centers

Abstract

A critical discussion is given of the recent calculations for the theoretical g‐shift in the electron paramagnetic resonance of F‐centers which is induced by nuclear hyperfine interactions. For cases requiring only the use of the contact hyperfine term of the first shell of nuclei, the computed g‐shift is found to be too small to be of interest. For F‐centers with large anisotropic hyperfine interaction constants, the concept of a hyperfine‐induced g‐shift may be given meaning only in terms of an electron‐nuclear double resonance experiment Under these circumstances, the experimentally observed hyperfine g‐shifts are comparable, to the shifts induced by spin‐orbit effects, but the theoretical computation would require an extensive computer program. It is noted that the computation of such g‐shifts is of only formal interest, since the sign of the experimentally determined g‐shift is not a positive definite criterion for assignment of the sign of the electronic charge of a paramagnetic radical.