Hyperfine-correlated electron nuclear double resonance spectroscopy

A pulse electron nuclear double resonance method is proposed that correlates the hyperfine splittings to the nuclear transition frequencies in a two-dimensional experiment. Since the technique makes use of selective radio frequency excitation in a time-domain experiment it can be applied to ordered systems as well as to disordered systems with hyperfine inhomogeneities and no or only small nuclear quadrupole inhomogeneities. The intensity of artifact peaks is found to depend on the phase of the radio frequency field which in turn is defined with respect to the geometry of the spin system. The theoretical predictions are confirmed by experiments on a single crystal and on a spin-label-doped polymer.