Time resolved infrared studies of weak magnetic field effects on radical pair solutions

The thesis describes the development, implementation and application of the first magnetic field time resolved infrared (MFTRIR) spectrometer, capable of studying the kinetics of radical reactions and the effect of weak magnetic fields upon them. The thesis commences with an overview of the theoretical concepts associated with free radicals and their reactions. The idea of the radical pair is presented and the magnetic field susceptibility of this species is discussed in the context of the radical pair mechanism. The construction and development of the MFTRIR spectrometer is then examined, highlighting the important design features and operational principles. The remaining chapters comprise an in depth analysis of the results obtained from the first studies performed using the spectrometer. The radical recombination kinetics and magnetic field dependence are studied for a range of precursor molecules with insights drawn into the structural factures that influence both the magnitude and form of the observed magnetic field effects. Later chapters explore the effects of the radical pair environment by investigating reactions in both isotropic solution and reverse micelle environments. A number of key findings are generated by this work. First is the excellent capability of the new instrument in measuring very small perturbations on radical reactions with weak magnetic fields. Second is the correlation between the size of the observed field effects and the magnetic parameters of the radicals. Third is the ability to remove the effects at very weak magnetic fields (approximately 2mT) without perturbing the effects at higher magnetic fields, through the selective removal of longer lived radical pairs.