Hydrazinelike Defect, N2H4+, in Irradiated Ammonium Halides. I Production and Characterization

The hydrazinelike defect in irradiated ammonium halides has been studied using electron paramagnetic resonance. The results suggest that this defect is an N2H4+ molecular ion at a normal ammonium ion lattice site. In NH4Cl and NH4Br it freezes in the lattice in such a way that the p orbitals in which the unpaired spin is localized are aligned along a 〈110〉 direction. The defect appears to be produced as a result of chemical decomposition of NH3X centers (X=halogen) through the competetive processes: NH3X→NH2++X−+H0 and NH3X→NH20+X−+H+. Products of these reactions then combine to form N2H4+ in the following way: NH20+NH2+→N2H4+. The N2H4+ subsequently undergoes decomposition at higher temperatures, its stability at any given temperature being also influenced by impurities.