PULSED TRANSIENT NUTATION EXPERIMENTS OF THE PHOTO-EXCITED TRIPLET-STATE

Pulsed transient nutation (TN) techniques have been employed to invest igate the transient spin dynamics of the photo-excited triplet state o f pentacene in p-terphenyl crystals using an X-band pulsed EPR spectro meter, The time evolution of the longitudinal magnetization of the tri plet state is monitored in the electron-spin-echo-detected TN experime nts, Different transient responses have been observed in the low-field and the high-field transitions, The observed TN decay signals are aff ected by the deuteration of the guest and host molecules, These differ ences may arise from the effectiveness of the electron-nuclear cross p olarization which is governed by the nonsecular hyperfine tensor eleme nts. Spin coherence effects in the cross polarization have been observ ed in the time-resolved dynamic nuclear polarization experiments induc ed by a nutation (microwave) pulse. (C) 1995 Academic Press, Inc.