Cr. Timmel et Pj. Hore, FLIP-ANGLE EFFECTS IN FOURIER-TRANSFORM EPR-SPECTRA OF SPIN-CORRELATED RADICAL PAIRS, Chemical physics letters, 226(1-2), 1994, pp. 144-150
The EPR spectra of spin-correlated radical pairs in pulse-acquire Four
ier-transform experiments are explored by means of spectral simulation
s. In particular, the dependence on the flip-angle (alpha) of the micr
owave pulse is examined. The spectra are seen to be linear combination
s of two sub-spectra, with amplitudes proportional to sin alpha and si
n 2alpha, which have distinctive shapes both for idealised dipolar-cou
pled radical pairs with isotropic g-values and no hyperfine couplings,
and under the conditions found for radical pair intermediates in phot
osynthetic energy conversion. In cases of poor resolution, the two sub
-spectra contain independent information on the structure and interact
ions of the radical pairs, which should supplement data available from
the more routine time-resolved continuous-wave experiment.