Stimulated nuclear polarization

On the other hand, in accord with the free radical mechanism peroxynitrite is dissociated into free radicals, which are supposed to be genuine reactive species. Although free radical mechanism was proposed as early as in 1970 [111], for some time it was not considered to be a reliable one because a great confusion ensued during the next two decades because of misinterpretations of inconclusive experiments, sometimes stimulated by improper thermodynamic estimations [85]. The latest experimental data supported its reliability [107-109]. Among them, the formation of dityrosine in the reaction with tyrosine and 15N chemically induced dynamic nuclear polarization (CIDNP) in the NMR spectra of the products of peroxynitrite reactions are probably the most convincing evidences (see below). 

Mims ENDOR is based on the stimulated echo sequence with three nonselec-tive m.w. n/2 pulses (Fig. 14b). The preparation part, nil - r - nil, creates a r-dependent grated polarization pattern. During the mixing period, the polarization is changed by a selective r.f. pulse if it is on-resonance with a nuclear frequency. The electron polarization is then detected via a stimulated echo created at time r after the last nil m.w. pulse. The ENDOR efficiency is given by [64]... 

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