Abstract
Electron paramagnetic resonance (EPR) study of γ‐irradiated ammonium chloride single crystals doped with Pd(II) revealed the formation of paramagnetic Pd(I) and Pd(III) centers at room temperature. Pd(I) has been found to be in a square planar coordination; its g values and chlorine superhyperfine constants suggest a possible formation of (NH4)2 PdCl4 in NH4Cl lattice. Pd(III) with low spin configuration has been found to be in a compressed octahedral coordination. Pd(III) in such a coordination presumably forms owing to the hole trapping of Pd(II) ions situated at the interstitial positions in the ammonium chloride lattice.