ESR study of exchange interaction in Würster's blue Perchlorate

ESR linewidth with magnetic field parallel to the a0-axis of a crystalline Würster's Blue Perchlorate showed a remarkable temperature variation below Tc = 190 K. The change of effective exchange interaction was found to be proportional to the spin density of the triplet state. The 103 effect was observed by the ESR of X-band and low frequencies at temperatures between 110 and 190 K with powder samples. Deviation of the line shape from Lorentzian shape showed low dimensionality in the exchange interaction.