ESR spectra of photolysis products from inorganic peracids and peroxyhydrates

The O-O bond is broken by low-temperature photolysis in polycrystalline peroxosulfate, peroxophosphate, and electrolytic peroxocarbonate. The radicals are stable at room temperature and their ESR spectra show appreciable hyperfine structure. Solid peroxyhydrates under these conditions give the radicals found in frozen solutions of H₂O₂. The differences in the ESR spectra may serve to distinguish the true peroxides from the peroxyhydrates. Two specimens of peroxocarbonate prepared by chemical methods have been shown in this way to be mixtures of peroxocarbonate with peroxyhydrate.