Carotenoid deactivation in an artificial light-harvesting complex via a vibrationally hot ground state

Savolainen, Janne; Buckup, Tiago; Hauer, Jürgen; Jafarpour, Aliakbar; Serrat, Carles; Motzkus, Marcus; Herek, Jennifer Lynn

doi:10.1016/j.chemphys.2009.01.002

Cited by 29 publications

(39 citation statements)

References 40 publications

(84 reference statements)

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“…8). It also supports the conclusion of Motzkus and co-workers that S* is the vibrationally hot ground electronic state S 0 *, 4,8,36 yet the formation mechanism of the hot molecules from S 1 suggested here is in line with the very early study of Gillbro and co-workers. 9 Absorption features on the red side of the GSB, the transient spectral characteristics and the observed time constants are fully consistent with a vibrationally hot ground electronic state ( Fig.…”

Section: Global Analysissupporting

confidence: 92%

“…In previous studies, a different intensity dependence of S* and S 1 absorption has been reported, suggesting that the S* state absorption features become more prominent at increasing excitation intensities. 10,36 Papagiannakis et al suggested either an ''inhomogeneous model'', where excitation of two different ground state conformers is involved, or a ''two-photon model'', where an electronically excited state S* is populated from a higher electronic state after two-photon excitation (with S 1 being generated from S 2 ). They favored the latter model based on simulation results.…”

Section: Global Analysismentioning

confidence: 99%

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Assignment of carotene S* state features to the vibrationally hot ground electronic state

Lenzer

Ehlers

Scholz

et al. 2010

Phys. Chem. Chem. Phys.

119

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The so-called S* state has been suggested to play an important role in the photophysics of beta-carotene and other carotenoids in solution and photosynthetic light-harvesting complexes, yet its origin has remained elusive. The present experiments employing temperature-dependent steady-state absorption spectroscopy and ultrafast pump-supercontinuum probe (PSCP) transient absorption measurements of beta-carotene in solution demonstrate that the spectral features of S* are due to vibrationally excited molecules in the ground electronic state S(0). Characteristic spectral signatures, such as a highly structured bleach below 500 nm and absorption in the range 500-660 nm result from the superposition of hot S(0) absorption ("S(0)*") on top of the ground-state bleach of room-temperature molecules. Appearance and disappearance of the S(0)* molecules can be completely described by a global kinetic analysis employing time-dependent species-associated spectra without the need to invoke the population of an intermediate electronically excited state.

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Section: Global Analysissupporting

confidence: 92%

Section: Global Analysismentioning

confidence: 99%

Assignment of carotene S* state features to the vibrationally hot ground electronic state

Lenzer

Ehlers

Scholz

et al. 2010

Phys. Chem. Chem. Phys.

119

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“…Depending on the chain length of the investigated carotenoid, the S* lifetime can be substantially longer or on the same time scale as S 1 . As first described for long-chain β-carotene homologues, 14 S* has been interpreted as a separate electronic excited state, 15−20 an excited state isomer, 21 a vibrationally hot ground state, populated by either Impulsive Stimulated Raman Scattering (ISRS) 22,23 or relaxation form S 1 , 24,25 the product of different ground state isomers, 11,26,27 or as the result of chemical impurities. 28 We note that none of the proposed energy level models is able to explain all experimental findings in literature.…”

Section: Introductionmentioning

confidence: 99%

Explaining the Temperature Dependence of Spirilloxanthin’s S* Signal by an Inhomogeneous Ground State Model

et al. 2013

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We investigate the nature of the S* excited state in carotenoids by performing a series of pump–probe experiments with sub-20 fs time resolution on spirilloxanthin in a polymethyl-methacrylate matrix varying the sample temperature. Following photoexcitation, we observe sub-200 fs internal conversion of the bright S2 state into the lower-lying S1 and S* states, which in turn relax to the ground state on a picosecond time scale. Upon cooling down the sample to 77 K, we observe a systematic decrease of the S*/S1 ratio. This result can be explained by assuming two thermally populated ground state isomers. The higher lying one generates the S* state, which can then be effectively frozen out by cooling. These findings are supported by quantum chemical modeling and provide strong evidence for the existence and importance of ground state isomers in the photophysics of carotenoids.

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“… 46 − 48 The fact that removal of population from S 2 only affects S 1 but not S* lead to the interpretation that S 1 must be an electronic excited state, populated via S 2 , while S* must be populated instantaneously, i.e., by pump pulse-induced Raman-scattering 49 or by two-photon interaction. 21 For both interpretations, the pump pulse has to be spectrally broad in order to populate vibrationally high-lying states on S 0 . Jailaubekov et al 25 tested this aspect of the hot ground state hypothesis and found that S* gets populated, regardless of the spectral width of the pump pulse.…”

mentioning

confidence: 99%

A Unified Picture of S* in Carotenoids

Balevičius

Abramavičius

Polı́vka

et al. 2016

J. Phys. Chem. Lett.

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In π-conjugated chain molecules such as carotenoids, coupling between electronic and vibrational degrees of freedom is of central importance. It governs both dynamic and static properties, such as the time scales of excited state relaxation as well as absorption spectra. In this work, we treat vibronic dynamics in carotenoids on four electronic states (|S0⟩, |S1⟩, |S2⟩, and |Sn⟩) in a physically rigorous framework. This model explains all features previously associated with the intensely debated S* state. Besides successfully fitting transient absorption data of a zeaxanthin homologue, this model also accounts for previous results from global target analysis and chain length-dependent studies. Additionally, we are able to incorporate findings from pump-deplete-probe experiments, which were incompatible to any pre-existing model. Thus, we present the first comprehensive and unified interpretation of S*-related features, explaining them by vibronic transitions on either S1, S0, or both, depending on the chain length of the investigated carotenoid.

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Carotenoid deactivation in an artificial light-harvesting complex via a vibrationally hot ground state

Cited by 29 publications

References 40 publications

Assignment of carotene S* state features to the vibrationally hot ground electronic state

Assignment of carotene S* state features to the vibrationally hot ground electronic state

Explaining the Temperature Dependence of Spirilloxanthin’s S* Signal by an Inhomogeneous Ground State Model

A Unified Picture of S* in Carotenoids

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