W-band (95 GHz) electron spin echo envelope modulation (ESEEM) is proposed
as a method for simultaneously determining the relative orientation and sep
aration of the constituents of spin-correlated radical I,airs in the solid
state. The discussion focuses on the transient secondary radical pair in ba
cterial photosynthetic energy conversion. (C) 2001 Elsevier Science B.V. Al
l rights reserved.