2A. N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
3Faculty of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia
* To whom correspondence should be addressed.
Received March 17, 2022; Revised April 19, 2022; Accepted May 6, 2022
Transient absorption dynamics of chlorophylls a and d dissolved in tetrahydrofuran was measured by the broadband femtosecond laser pump-probe spectroscopy in a spectral range from 400 to 870 nm. The absorption spectra of the excited S1 singlet states of chlorophylls a and d were recorded, and the dynamics of the of the Qy band shift of the stimulated emission (Stokes shift of fluorescence) was determined in a time range from 60 fs to 4 ps. The kinetics of the intramolecular conversion Qx→Qy (electronic transition S2→S1) was measured; the characteristic relaxation time was 54 ± 3 and 45 ± 9 fs for chlorophylls a and d, respectively.
KEY WORDS: chlorophyll a, chlorophyll d, femtosecond laser spectroscopy, excited state spectrum, Stokes shift dynamics, internal conversion