CIDNP in a double switched magnetic field

A new time-resolved technique is described to study the spin dynamics and chemical kinetics of short-lived radicals in weak magnetic fields. The idea of CIDNP in a double switched magnetic field has been proposed previously by Lukzen, et al., and involves the double non-adiabatic switching of the magnetic field during the lifetime of the radicals. Information concerning the spin dynamics and chemical kinetics is obtained from the effect of the two magnetic switchings on the nuclear polarization of the radicals and, thus, on the CIDNP of their diamagnetic products. Oscillations of the CIDNP intensity as a function of time delay between switches of the magnetic field have been observed. Calculations and analysis of the experimental kinetics show that the initial populations of the nuclear spin levels of intermediate radicals determine the frequency and phase of the oscillations.