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- Title
Effects of tunable excitation in carotenoids explained by the vibrational energy relaxation approach.
- Authors
Balevičius, Vytautas; Lincoln, Craig N.; Viola, Daniele; Cerullo, Giulio; Hauer, Jürgen; Abramavicius, Darius
- Abstract
Carotenoids are fundamental building blocks of natural light harvesters with convoluted and ultrafast energy deactivation networks. In order to disentangle such complex relaxation dynamics, several studies focused on transient absorption measurements and their dependence on the pump wavelength. However, such findings are inconclusive and sometimes contradictory. In this study, we compare internal conversion dynamics in $$\beta$$ -carotene, pumped at the first, second, and third vibronic progression peak. Instead of employing data fitting algorithms based on global analysis of the transient absorption spectra, we apply a fully quantum mechanical model to treat the high-frequency symmetric carbon-carbon (C=C and C-C) stretching modes explicitly. This model successfully describes observed population dynamics as well as spectral line shapes in their time-dependence and allows us to reach two conclusions: Firstly, the broadening of the induced absorption upon excess excitation is an effect of vibrational cooling in the first excited state ( $$S_{1}$$ ). Secondly, the internal conversion rate between the second excited state ( $$S_{2}$$ ) and $$S_{1}$$ crucially depends on the relative curve displacement. The latter point serves as a new perspective on solvent- and excitation wavelength-dependent experiments and lifts contradictions between several studies found in literature.
- Subjects
CAROTENOID analysis; LIGHT-harvesting complex (Photosynthesis); PHOTOSYSTEMS; EXCITATION spectrum; ABSORPTION spectra; INTERNAL conversion (Nuclear physics)
- Publication
Photosynthesis Research, 2018, Vol 135, Issue 1-3, p55
- ISSN
0166-8595
- Publication type
Article
- DOI
10.1007/s11120-017-0423-6