Equilibration Dependence of Fucoxanthin S-1 and ICT Signatures on Polarity, Proticity, and Temperature by Multipulse Femtosecond Absorption Spectroscopy

0495163 - BC 2019 RIV US eng J - Journal Article
West, R.G. - Fuciman, M. - Staleva-Musto, H. - Šebelík, V. - Bína, David - Durchan, Milan - Kuznetsova, V. - Polívka, Tomáš
Equilibration Dependence of Fucoxanthin S-1 and ICT Signatures on Polarity, Proticity, and Temperature by Multipulse Femtosecond Absorption Spectroscopy.
Journal of Physical Chemistry B. Roč. 122, č. 29 (2018), s. 7264-7276. ISSN 1520-6106. E-ISSN 1520-5207
R&D Projects: GA ČR(CZ) GA16-10417S
Institutional support: RVO:60077344
Keywords : chlorophyll-a-protein * charge-transfer state * excitation-energy-transfer * pump-probe spectroscopy
OECD category: Biophysics
Impact factor: 2.923, year: 2018

To demonstrate the value of the multipulse method in revealing the nature of coupling between excited states and explore the environmental dependencies of lowest excited singlet state (S-1) and intramolecular charge transfer (ICT) state equilibration, we performed ultrafast transient absorption pump-dump-probe and pump-repumpprobe spectroscopies on fucoxanthin in various solvent conditions. The effects of polarity, proticity, and temperature were tested in solvents methanol at 293 and 190 K, acetonitrile, and isopropanol. We show that manipulation of the kinetic traces can produce one trace reflecting the equilibration kinetics of the states, which reveals that lower polarity, proticity, and temperature delay S-1/ICT equilibration. On the basis of a two-state model representing the S-1 and ICT states on the same S-1/ICT potential energy surface, we were able to show that the kinetics are strictly dependent on the initial relative populations of the states as well as the decay of the ICT state to the ground state. Informed by global analysis, a systematic method for target analysis based on this model allowed us to quantify the population transfer rates throughout the life of the S-1/ICT state as well as separate the S-1 and ICT spectral signatures. The results are consistent with the concept that the S-1 and ICT states are part of one potential energy surface.
Permanent Link: http://hdl.handle.net/11104/0288175