ELECTRON-PARAMAGNETIC RESONANCE IN SODIUM AMMONIUM-SULFATE DIHYDRATE OF RADICALS PRODUCED BY X-IRRADIATION

X-irradiation of sodium ammonium sulphate dihydrate produces a complex electron paramagnetic resonance spectrum indicating the production of five, or possibly six, different radicals. The relative concentration of these appears to depend upon the crystal growth, but not on subsequent treatment. Those with extensive hyperfine structure have been identified as NH3+ and NH+. Identification of the others, presumably derived from the SO4 group, is more tentative. The only change in the spectrum observed on cooling through the ferroelectric phase transition is a small doubling of the outermost hyperfine fines of NH4+, which suggests that all of the radicals produced are somewhat detached from the lattice, and so not very susceptible to changes in its structure.