ANOMALOUS PULSE-ANGLE AND PHASE DEPENDENCE OF HAHN ELECTRON-SPIN ECHOAND MULTIPLE-QUANTUM ECHOES IN A PHOTOINDUCED SPIN-CORRELATED RADICALPAIR

Formation of two- and three-pulse electron spin echoes and their anoma lous pulse-angle and phase dependence in a photoinduced spin-correlate d radical pair are examined. Analytical formulae for the unusual Hahn' s spin-echo signals and the two-pulse double-quantum echo are derived in terms of the pulse angle, microwave phase, and the time intervals b etween the laser pulse and the microwave pulses. Such anomalies are sh own to be present in both cases of singlet and tripler precursors. Pha se dependence and formation of the three-pulse stimulated echo and mul tiple-quantum echoes are also examined. (C) 1997 American Institute of Physics.