LOW MAGNETIC-FIELD ELECTRON-NUCLEAR RESONANCE TRANSITIONS DETECTED BYNUCLEAR-POLARIZATION OF RADICAL REACTION-PRODUCTS

The low magnetic field electron-nuclear resonance transitions, detecte d via changes in the nuclear polarization of radical reaction products , have been investigated. Due to the mixing of the wavefunctions in lo w magnetic fields such transitions are allowed as electron resonance t ransitions but at the same time lead to significant changes of nuclear polarization. The photolysis of 2,4,6-trimethylbenzoylphosphonic acid dimethyl ester has been used as a model reaction. It proceeds via the intermediate dimethoxyphosphonyl radical which has a large hyperfine constant (69.6-70 mT). It has been shown that this effect can be appli ed for the investigation of low field electron and nuclear polarizatio n. (C) 1998 Elsevier Science B.V.