The Effect of Light at Different Wavelengths on Electron Spin Resonances in Wool

An action spectrum from 280 nm to 390 nm for the formation of a non-sulphur-free radical in wool at room temperature and in the absence of air has been determined. This spectrum shows a peak at 285 nm, indicating that the aromatic amino acid components of keratin are important chromophores in the formation of these radicals. A low-temperature ESR signal in wool at g ~ 4.25 decreases on irradiation with light from a mercury arc through a Wratten 35 filter (320–470 nm). This signal arises from a ferric ion—keratin complex, and the photodegradation of this complex is accompanied by the formation of non-sulphur type radicals at room temperature.