CIDNP in a double switched magnetic field

A new time-resolved technique is described to study the spin dynamics and c hemical kinetics of short-lived radicals in weak magnetic fields. The idea of CIDNP in a double switched magnetic field has been proposed previously b y Lukzen, et al., and involves the double non-adiabatic switching of the ma gnetic field during the lifetime of the radicals. information concerning th e spin dynamics and chemical kinetics is obtained from the effect of the tw o magnetic switchings on the nuclear polarization of the radicals and, thus , on the CIDNP of their diamagnetic products. Oscillations of the CIDNP int ensity as a function of time delay between switches of the magnetic field h ave been observed. Calculations and analysis of the experimental kinetics s how that the initial populations of the nuclear spin levels of intermediate radicals determine the frequency and phase of the oscillations. (C) 2000 E lsevier Science B.V. All rights reserved.