FLUORESCENCE QUENCHING DUE TO THE ELECTRON-TRANSFER - INDOLE-CHLOROMETHANES IN RIGID ETHANOL GLASS

Fluorescence quenching of indole by chlorinated methanes in rigid matrices at low temperature have been studied with picosecond-laser excitation and steady-state illumination. Observed decay curves were significantly deviated from a single exponential in the presence of highly concentrated chloromethanes, and analyzed by the generalized decay function for the exchange interaction. The fluorescence quantum yields decreased exponentially with the concentration of added quenchers. These results were explained with the electron transfer mechanism from the excited indole to chloromethanes which were caused by the short range electron exchange interaction. The detailed mechanism of the electron transfer from the excited states are discussed and the similarity between the electron transfer and the triplet-triplet excitation transfer is emphasized. © 1979 American Institute of Physics.