Electron paramagnetic resonance of NH<inf> 3</inf>⁺ radical in potassium sulphate

Room temperature EPR spectra of (NH4)2SO4 doped K2SO4 monocrystals irradiated with x-rays show the presence of NH3 + radicals. The EPR parameters are g {norm of matrix}=2.0037 and g ⊥ = 2.0068;14N A XX=13.75;A YY=24.5;A ZZ=25.5 gauss;1H A XX=A YY=22 and A ZZ=25 gauss. From the14N and1H coupling constants it has been inferred that at room temperature the planar NH3 + radical undergoes rotation about the C 3 axis which corroborates with the equivalence of the protons, but the radical itself is in an asymmetric crystal field environment. The 77K spectra indicate a considerable reduction in the motion of the radical with the free motion almost completely stopped. © 1977 the Indian Academy of Sciences.