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.
Department of Physics and Astronomy, Faculty of Sciences, Vrije Universiteit, De Boelelaan 1081, 1081 HV, Amsterdam, The Netherlands. papagian@nat.vu.nl
Emmanouil
E
Papagiannakis
Mikas
M
Vengris
Delmar S
DS
Larsen
Ivo H M
IH
van Stokkum
Roger G
RG
Hiller
Rienk
R
van Grondelle
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