Trapped radical clusters and pairs as detected by ESR

Indirect evidence for radical pair formation in polymers has been obtained from the step-like character of radical decay at low temperature (section 4.2.1). 

Definite proof of radical clusters in PMMA was obtained recently by ESR. The variation of the spin—spin relaxation time with temperature in the 7-irradiated sample found by Bullock and Sutcliffe [136] provided strong and direct evidence for the formation of radicals in spurs. Further 

The same conclusion was obtained by Kevan and co-workers [138] for 7-irradiated ethylene glycol dimethacrylate by a similar power saturation method. A typical saturation curve is given in Fig. 24. The calculated spin 

THE RATIOS OF THE INTEGRATED INTENSITIES OF THE AMS=2 AND 1 SPECTRA OF A NUMBER OF IRRADIATED HIGH POLYMERS.3 

Radical pairs were detected recently by Wilske and Heusinger [140] in polystyrene irradiated at 77°K. If the polystyrene samples are warmed up, 

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