Thermodynamics and the Overhauser Nuclear Polarization Effect

Abstract

A thermodynamical treatment by Brovetto, Cini, and Ferroni of the Overhauser effect in metals and non-metals is extended to apply to nuclear relaxation processes other than that due to the contact interaction. Justification for the method is then presented by an application of the theory of the thermodynamics of irreversible processes using the point of view of the Onsager relations. According to a condition obtained for the validity of the method, the expressions derived for the population of adjacent nuclear Zeeman levels for Boltzmann and for Fermi statistics for the electrons hold essentially over the entire range of field and temperature at which the related experiments may be performed.