ROTATION OF A SPIN PROBE IN HYDRATED POLYETHYLENE GLYCOL BELOW FREEZING TEMPERATURE
The ESR spectra of a spin probe, 2,2,6,6-tetramethyl-4-piperidone N-oxide, in water-polyethylene glycol (PEG) systems were measured below freezing temperature. The activation energy of the rotation of the probe in the hydrated PEG was considerably large. It was explained in terms of the breaking of the hydrogen bonds of the hydration water.