ESR Linewidths in Dilute Hexaaquomanganese(II) Solutions at 9.4 and 24 kMc

Abstract

The electron spin resonance linewidth for Mn(H₂O)₆⁺⁺ in aqueous solution is examined in the temperature range 15° to 90°C, at frequencies of 9.4 and 24 kMc. The results are interpreted on the assumption that the linewidth is a measure of the spin‐lattice relaxation rate. As expected from previous NMR measurements of proton nuclear relaxation in such solutions, the linewidth decreases with increasing temperature, and is smaller at 24 kMc than at 9.4 kMc. The ESR results are approximately in agreement with the NMR results if the electronic relaxation time is assumed to follow a Bloembergen equation with the correlation time behaving with temperature according to an activation energy of 2.5 kcal/mole.