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Chemically Induced Dynamic Electron-Spin Polarization (CIDEP) in radiolytically generated H atoms in water-saturated Vycor glass is observed at different temperatures by time -resolved pulsed EPR spectroscopy. It is shown that the rate of longitudinal spin relaxation of the partner, the rate of encounters, and the rate of the spin-selective recombination of the H-atom with a partner are the most important kinetic parameters defining the observed evolution of CIDEP.

The formation of electron spin polarization in a nitroxide radical bound to a p-quinone in a molecular complex in low temperature organic glass is demonstrated. Spin polarization is shown to be mainly due to a polarization transfer from the lowest triplet state of the p-quinone. A theoretical model for the formation of spin polarization in the matrix-isolated radical-triplet pairs is suggested.

Stimulated nuclear polarization (SNP) and time resolved electron spin resonance (TR ESR) spectra help analyze the exchange interaction through micellar size during laser flash photolysis of alpha-methyldeoxybenzoin solubilized in alkyl sulfate micelles of different sizes. Hyperfine splitting in the SNP spectra decreases with micelle size, which is not observed in the experimental TR ESR spectra. The stochastic Liouville equation explains the qualitative differences of SNP and TR ESR spectra as a function of micelle size.

Estimations in different sized alkyl sulfate micelles were performed for the geminatic reaction probabilities of benzoyl/sec-phenethyl radical pairs, produced by the photolysis of alpha-methyldeoxybenzoin, for unlabeled and labeled ketones. The electron spin exchange reaction greatly affects the rate of geminate reaction of the unlabeled radical pairs in small micelles.

Time-resolved electron spin resonance spectroscopy is used to study the electron spin exchange interaction between micellized spin-correlated radical pairs and to effect the successful exchange interaction. The J values are a function of the radical pair molecular structure to a specified micelle size, and a function of the effective micelle size experienced by a specified micellized radical pair.

Studies on alkyl sulfate micelle of varying sizes enable the formation of a theoretical model which introduces a boundary factor to explain micelle boundary permeability. The model treats radical escape as a process occurring at the boundary. As the micelle size decreases, the electron spin exchange interaction slows down the rate and prevents intersystem crossing.

The article discusses the radical pair triplet states that are usually obtained by the time-resolved electron paramagnetic resonance at room temperature. The relationship existing between the different molecular triplets and the spin-polarized free radicals is also explained.