Use of ultrafast dispersed pump-dump-probe and pump-repump-probe spectroscopies to explore the light-induced dynamics of peridinin in solution.
Optical pump-induced dynamics of the highly asymmetric carotenoid peridinin in methanol was studied by dispersed pump-probe, pump-dump-probe, and pump-repump-probe transient absorption spectroscopy in the visible region. Dispersed pump-probe measurements show that the decay of the initially excited S2 state populates two excited states, the S1 and the intramolecular charge-transfer (ICT) state, at a ratio determined by the excitation wavelength. The ensuing spectral evolution occurs on the time scale of a few picoseconds and suggests the equilibration of these states. Dumping the stimulated emission of the ICT state with an additional 800-nm pulse after 400- and 530-nm excitation preferentially removes the ICT state contribution from the broad excited-state absorption, allowing for its spectral characterization. At the same time, an unrelaxed ground-state species, which has a subpicosecond lifetime, is populated. The application of the 800-nm pulse at early times, when the S2 state is still populated, led to direct generation of the peridinin cation, observed for the first time in a transient absorption experiment. The excited and ground electronic states manifold of peridinin has been reconstructed using target analysis; this approach combined with the measured multipulse spectroscopic data allows us to estimate the spectra and time scales of the corresponding transient states.
Papagiannakis
Emmanouil
E
Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands. papagian@nat.vu.nl
Vengris
Mikas
M
Larsen
Delmar S
DS
van Stokkum
Ivo H M
IH
Hiller
Roger G
RG
van Grondelle
Rienk
R
D002338:Carotenoids / Q000737:chemistry* / Q000528:radiation effects*; D008027:Light; D015394:Molecular Structure; D010777:Photochemistry; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry; D013057:Spectrum Analysis / Q000379:methods
D012996:Solutions; C016040:peridinin; D002338:Carotenoids