Die kinetik der selbst-sensibilisierten photooxidation des heterocoerdianthrons im bereich niedriger konzentrationen

Abstract

The self-sensitized photooxidation of heterocoerdianthrone was investigated in air-saturated benzene and carbon disulfide as a function of substrate concentration at 25 °C. At very low concentrations the overall quantum yield was found to be independent of substrate concentration. This effect is interpreted in terms of a re-encounter of O 2( 1Δ g) and ground state substrate molecules generated in the same triplet—triplet annihilation act. In both solvents the overall re-encounter probability is found to be 0.74. In benzene the overall quantum yield is independent of substrate concentration at concentrations <10 −6 M, in carbon disulfide at concentrations <10 −7 M. It can be shown that this results from the different life times of O 2( 1Δ g) in the respective media.