EXCITON-CONTROLLED PROTON RELAXATION TIMES IN SOME ION RADICAL SALTS OF TCNQ

Proton spin-lattice relaxation times in several ion-radical salts of TCNQ have been measured over a range of temperature. The temperature dependence of 7i in these materials (which contain thermally activated triplet excitons) suggests that τc, the correlation time of the relaxation mechanism, may be written as τc-1= τ0-1ρ, where ρ is the exciton density per lattice site and τ0 a time characteristic of the system. This assertion is supported by a very close agreement of correlation-time activation energies and tripletexciton activation energies.