Radical pair reactions weak magnetic fields

The ion pair spin multiplicity may be a valuable tool to affect the BET rates and to probe the ion pair dynamics via magnetic field effects [36], Even weak magnetic fields are known to influence relative probabilities of singlet and triplet reactions [34], Chemically induced dynamic nuclear polarization (CIDNP) is a particularly informative technique [12]. Many bond scission reactions and rearrangements in cyclic radical ions have been successfully explored using this approach. Both structural data (spin densities) and approximate kinetic informations are indirectly available from such experiments [12]. 

Here we will report on the effects of magnetic fields on the primary reactions in RCII complexes. Such effects have been extensively studied in purple bacteria (see (7)) and PSI (8). Generally, Ot is decreased by weak fields (<1 kGauss) and the lifetime of the radical pair is increased in purple bacteria (but not in PSI (8)). Our results for RCII complexes are qualitatively similar to those for purple bacteria. 

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