Nuclear-electron double resonance in solutions of potassium nitrosyl sulphonate and of potassium nitrosyl pentacyano chromium (III)

Abstract

The effect on the nuclear resonance spectra of exciting the electron resonance in solutions of free radicals has been studied in a magnetic field of about 3000 G. The nuclei and electrons are coupled by dipole-dipole interactions. The nuclear polarization produced by a given microwave power varies in a roughly linear manner with the logarithm of the concentration of radical and this can be interpreted in terms of a set of rate equations relating the build up and decay of nuclear polarization. The presence of oxygen or of para ­ magneticions reduces the nuclear polarization obtainable, and it is established that this effect depends primarily on the change of the nuclear spin-lattice relaxation time. A quantitative discussion of these effects is given.