Singlet and triplet excited states dynamics of photosynthetic pigment chlorophyll a investigated by sub-nanosecond pump-probe spectroscopy

Singlet and triplet excited states dynamics of the photosynthetic pigment chlorophyll a in various solvents have been investigated by sub-ns pump-probe spectroscopic measurements with a sub-ns time resolution and a temporal window up to 400 mu s. The singlet and triplet lifetimes of chlorophyll a were determined respectively to be 5.2-7.0 ns and 1.2-12 mu s depending on solvents. On a basis of a global analysis of time-resolved spectroscopic data, we estimated an yield of the intersystem crossing from the singlet to triplet excited states chlorophyll a to be about 30% depending not on surrounding environments. The value is much lower than the previously reported values. (C) 2017 Elsevier B.V. All rights reserved.