Nuclear magnetic relaxation of1H in organic cation radical saltm-MPYNN+X− (X=ClO4, BF4)

Abstract

The nuclear spin-lattice relaxation timeT 1 of1H in the organic cation radical saltm-MPYNN+X− (X=ClO4, BF4) has been measured in the temperature range 1.5∼200K and in the field range 1∼70kOe. The experimental results in high fields were well interpreted in terms of flip-flop relaxation process involving the pairs of ferromagnetic dimers, whose energy scheme consists of lower triplet- and upper singlet-states with the gap energy of 20K. An appreciable increase of the relaxation rate in low fields below about 10kOe was explained by the direct relaxation process due to the band-like spread of each Zeeman level.