Picosecond study of an electron transfer in the first excited state of dodci

Abstract Electron transfer from the first excited singlet state of a polymethine cyanine dye. DODCI, to various electron acceptors ( p -benzoquinone, p -dinitrobenzene and methylviologen) was investigated using picosecond fluorescence and absorption spectroscopy. The electron transfer to methylviologen was confirmed by conventional nanosecond laser spectroscopy. Its efficiency, as expressed by the ratio k 5 /( k 4 + k 5 ) = 0.07. can be explained by coulombic repulsion in the initial radical pair. On the other hand, although fluorescence quenching by p -BQ and p -DNB is very efficient, no electron transfer was observed.