Radical-triplet pair mechanism of electron spin polarization. Detailed theoretical treatment.

Specific features of net chemically induced dynamic electron spin polarization (CIDEP) P(n), generated in liquid-phase triplet-radical (TR) quenching, are analyzed in detail within the general model, which allows for fairly simple analysis of CIDEP both numerically and analytically. This model enables one to accurately treat nonadiabatic transitions between the terms of TR-pair spin Hamiltonian, resulting in CIDEP generation. The proposed theory predicts fairly simple analytical dependence of P(n) on parameters of the model. In particular, it is shown that within the wide region of parameters the P(n) dependence on the coefficient of relative TR diffusion D(r) is described by simple linear relation P(n)(-1)(D(r)) ≈ Q0 + q̅(n)D(r) (Q0 and q̅(n) are independent of D(r)). It is also demonstrated that obtained numerical and analytical results are very helpful for the analysis of experimental data, which is demonstrated by analyzing the experimental D(r)-dependence of P(n).