HOW TO MEASURE DIFFUSION CONSTANT AND ABSOLUTE SUSCEPTIBILITY OF CHARGE-CARRIERS AT THE SAME TIME

Multiple spin echos can be excited for spin-1/2 systems by two radiofr equency pulses with tipping angles unequal to 180 degrees, if the abso lute magnetization is sufficiently large. If a magnetic field gradient is applied, the attenuation of the primary echo reveals the diffusion constant of these spins, whereas the ratio of primary and secondary e cho amplitudes indicates the absolute magnetic susceptibility of the r esonating spins. This potentiality is examined here numerically and by application of nuclear magnetic resonance to liquid samples containin g protons. We analyse the complications that have to be overcome, if t his technique is used for the study of the charge and spin carriers in low-symmetry quasi-one-dimensional organic conductors. Reasonable acc uracy is obtained for the parameters derived for the conduction electr ons of perylene radical cation salts.