Chemically induced dynamic spin polarization in two dimensional systems: Theoretical predictions

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Abstract
Theoretical predictions for chemically induced dynamic spin polarization [CIDN(E)P] and Heisenberg spin exchange in two dimensional fluid systems are developed. An idealized model, which yields simple limiting results is first discussed in order to illustrate the importance of the geometrical aspects of this problem upon the CIDN(E)P observables. Pedersen–Freed theory, which employs numerical solutions of the stochastic‐Liouville equation is then applied. This approach is appropriately modified in its use and analysis in order to fully exhibit the details of two dimensional kinetic and polarization processes. Specifically, the Laplace transformed results are calculated and related to the finite time results (rather than the t→∞ asymptotes) due to logarithmic divergences in time which characterize two dimensional processes. Approximate empirical formulas are developed to describe our exact numerical results and they illustrate the profound effects of a change of dimensionality on the CIDN(E)P observables. These results are related to experimental observables by considering the role of processes which limit the time scale for the polarization (e.g., radical scavenging and T1) and by a consideration of the role of two dimensional bimolecular encounter theory on random initial encounters. Other aspects of two dimensional effects (e.g., time‐dependent diffusion coefficients and concentration effects) are briefly noted.