PULSED ESR ON THE ORGANIC ION RADICAL SALT - ETHYL-4,4'-DIMETHYL-2,2'-THIAZOLOCYANINE-[TCNQ](2)

We present first T-1e(-1) and T-2e(-1) measurements on the organic ion radical salt elhyl-4,4'-dimethyl-2,2'-thiazolocyanine-(TCNQ)(2) as fu nction of temperature and of orientation. The electronic spin diffusio n constant could be determined directly by the electron spin echo fiel d gradient technique: D (300 K) = 0.03 +/- 0.02 cm(2)/sec. Pulsed ESR experiments have - in comparison to conventional cw-ESR - the advantag e to monitor via T-1e(-1) and T-2e(-1) the spectral density of dynamic al processes at different frequencies. This is shown in a general mann er on thyl-4,4'-dimethyl-2,2'-thiazolocyanine-(TCNQ)(2). Between 300 a nd 60 K, T-1e(-1) and T-2e(-1) are close in amplitude and have a simil ar temperature dependence. At 60 K their degeneracy is lifted, yieldin g a quantitative value for the effective spin exchange between localiz ed spins tau(ex)(-1) = 6 . 10(10) sec(-1) and via the absolute value o f the relaxation an average distance of the localized centers of about 12 Angstrom. The dynamical data as evaluated above cannot be correlat ed with the conductivity, clearly indicating that the conduction elect rons are a minority, not being monitored by the ESR-experiments.