Observation of hydrated electron, (SCN)2 .- and CO3 .- radical in high temperature and supercritical water

Transient radicals (hydrated electron, (SCN)₂ ^.- and CO₃ ^.-) formed in supercritical water have been observed by the pulse radiolysis technique. The change of spectra of these radicals with temperature has been measured. It was found that the spectra and absorption coefficients of the radicals, e^- _aq and (SCN)₂ ^.-, are strongly dependent on the temperature of the water. Since it was found that the absorption spectrum and molar absorption coefficient of CO₃ ^.- radical seem to be almost independent of temperature, G-values of OH and e^- _aq could be derived. Then, the absolute values of the absorption coefficients for the radicals could be calculated. The G-values of the radical products in water radiolysis tend to increase with increasing temperature up to 400°C. Based on the above observation, radiolysis of supercritical water is discussed.