Photochemical behavior in dichromated gelatin

The photochemical behavior of dichromated gelatin and of different aminoacids-chromium (VI) systems was investigated. The photoredox process that takes place between chromium (VI) (complexed or not) and the organic moiety leads to the formation of chromium (V) which is then reduced to chromium (III) likely complexed in the medium. In chromium (VI)-aminoacids systems, the quantum yield Phi, that measures the efficiency of a photon at a given wavelength, strongly depends on the reductive properties of the aminoacid. Phi is proportional to aminoacid concentration. In irradiated DCG films, the formation of chromium (V) is observed and this intermediate species appears to be surprisingly stable in the polymeric matrix.