Effects of very strong magnetic fields on radical reactions: the role of g-value anisotropy

For small radicals in mobile liquids, the anisotropy of the g-value and hyp erfine tensors is normally averaged out by molecular rotations. In the very strong magnetic fields (1-30 T) now in use for chemical studies, this may not be true: Larmor precession is so fast that even small differences due t o differences in orientation can have a significant effect. The 'reversion' or reversal of direction of magnetic field effects on some radical pair re actions above 1 T may be due in part to this effect. The proposal is suppor ted by numerical calculations. (C) 2001 Elsevier Science B.V. All rights re served.