Proton Zeeman relaxation in NH4ClO4with natural and enriched deuteron concentrations

Abstract
The Zeeman relaxation of protons in two NH4ClO4 samples with natural (0.015%) and 0.1% deuteron concentrations was studied at the proton resonance frequencies 18 MHz and 22 MHz in the temperature range from 4.2 to 30K. The effect of deuterons on the relaxation becomes observable below 20K and increases with decreasing temperature. The additional minima observed in the proton relaxation time below 20K are shown to be characteristic of pure NH4ClO4. The non-exponentiality of the relaxation bears some resemblance to the relaxation in the presence of paramagnetic impurity centres.