Electron spin resonance spectra of aged, γ‐irradiated polystyrenes

The electron spin resonance spectrum of polystyrene that has been γ‐irradiated at −196°C. changes gradually with time from a broad three‐peaked structure with outer derivative peaks at ±46 gauss to a much narrower structure with poorly separated outer derivative peaks at ±21–24 gauss. The deuterated polystyrenes behave likewise in general. The aged radicals of α,β,β‐trideuterostyrene and β,β‐dideuterostyrene exhibit only a single peak with derivative maxima at ±7 or 8 gauss from center. The aged spectra are all consistent with the hypothesis of major hyperfine interaction with β hydrogens. During the aging about 80% of the original radicals are lost, but the remainder are very long‐lived. Poorly evacuated samples or those with added benzene decay much more rapidly.