The state energy and the displacements of the potential minima of the 2Ag− state in all-trans-β-carotene as determined by fluorescence spectroscopy

Onaka, Kengo; Fujii, Ritsuko; Nagae, Haruki; Kuki, Michitaka; Koyama, Yasushi; Watanabe, Yasutaka

doi:10.1016/s0009-2614(99)01212-9

Cited by 70 publications

(79 citation statements)

References 20 publications

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“…97 Formally, ␤-carotene has 11 double bonds in the polyene backbone, but by comparing the excitation energies of the polyenes with our ␤-carotene excitation energies, we can estimate a reduced conjugation length of 9.5-9.7 bonds, which is very close to the experimental estimate of 9.7 of Onaka et al 71 ͑Fig. 7͒.…”

Section: Discussionsupporting

confidence: 85%

“…Recent studies using resonance Raman excitation profiles and electronic absorption spectroscopy on substituted polyenes in the carotenoid family have indicated the presence of additional dark states below the 1B u + state. [68][69][70][71][72] In particular, for the all-trans-carotenoids with ͑the number of double bonds͒ n = 9 -11, Sashima et al 67 and Cerullo et al 73 72 The assignment was made by extrapolating from the earlier Pariser-ParrPople multi-reference doubles configuration interaction calculations by Tavan and Schulten on short polyenes ͑n =2-8͒, which had predicted the existence of these additional states. 56 To better understand the electronic structure of these low-lying states, we would ideally like to be able to carry out an ab initio multireference calculation using the complete -valence space.…”

Section: Introductionmentioning

confidence: 99%

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Orbital optimization in the density matrix renormalization group, with applications to polyenes and β-carotene

Ghosh¹,

Hachmann²,

Yanai³

et al. 2008

The Journal of Chemical Physics

361

447

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In previous work we have shown that the density matrix renormalization group ͑DMRG͒ enables near-exact calculations in active spaces much larger than are possible with traditional complete active space algorithms. Here, we implement orbital optimization with the DMRG to further allow the self-consistent improvement of the active orbitals, as is done in the complete active space self-consistent field ͑CASSCF͒ method. We use our resulting DMRG-CASSCF method to study the low-lying excited states of the all-trans polyenes up to C 24 H 26 as well as ␤-carotene, correlating with near-exact accuracy the optimized complete -valence space with up to 24 active electrons and orbitals, and analyze our results in the light of the recent discovery from resonance Raman experiments of new optically dark states in the spectrum.

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Section: Discussionsupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Orbital optimization in the density matrix renormalization group, with applications to polyenes and β-carotene

Ghosh¹,

Hachmann²,

Yanai³

et al. 2008

The Journal of Chemical Physics

361

447

View full text Add to dashboard Cite

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“…In a preceding publication, 13 we determined the two-photon excitation spectrum of the Car S 1 state in PS I, which agreed very well with known data about -carotene in the literature 19 (Figure 2). Here, we present time-resolved fs pump-probe data observed after twophoton excitation of the optical dark state and probing its strong Car S 1 f Car S n transient absorption.…”

Section: Introductionsupporting

confidence: 85%

Time-Resolved Two-Photon Spectroscopy of Photosystem I Determines Hidden Carotenoid Dark-State Dynamics

Wehling

Walla

2005

J. Phys. Chem. B

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We present time-resolved fs two-photon pump-probe data measured with photosystem I (PS I) of Thermosynechococcus elongatus. Two-photon excitation (λ exc /2 ) 575 nm) in the spectral region of the optically forbidden first excited singlet state of the carotenoids, Car S 1 , gives rise to a 800 fs and a 9 ps decay component of the Car S 1 f S n excited-state absorption with an amplitude of about 47 ( 16% and 53 ( 10%, respectively. By measuring a solution of pure -carotene under exactly the same conditions, only a 9 ps decay component can be observed. Exciting PS I at exactly the same spectral region via one-photon excitation (λ exc ) 575 nm) also does not show any sub-ps component. We ascribe the observed constant of 800 fs to a portion of about 47 ( 16% -carotene states that can potentially transfer their energy efficiently to chlorophyll pigments via the optically dark Car S 1 state. We compared these data with conventional one-photon pump-probe data, exciting the optically allowed second excited state, Car S 2 . This comparison demonstrates that the fast dynamics of the optically forbidden state can hardly be unravelled via conventional one-photon excitation only because the corresponding Car S 1 populations are too small after Car S 2 f Car S 1 internal conversion. A direct comparison of the amplitudes of the Car S 1 f S n excited-state absorption of PS I and -carotene observed after Car S 2 excitation allows determination of a quantum yield for the Car S 1 formation in PS I of 44 ( 5%. In conclusion, an overall Car S 2 f Chl energy-transfer efficiency of ∼69 ( 5% is observed at room temperature with 56 ( 5% being transferred via Car S 2 and probably very hot Car S 1 states and 13 ( 5% being transferred via hot and "cold" Car S 1 states.

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“…However, the assumption of a single accepting mode is not valid in β-carotene, which falls in Englman's strong-coupling limit 12 and has several modes of similar frequency and with very large displacements between S 1 and S 0 that may act as acceptor modes during IC. 37 By partitioning the IC energy into both the C=C and C-C modes, the Franck-Condon overlap between the relaxed S 1 state and the isoenergetic S 0 state can be dramatically increased. Also, because each of these modes would be similarly affected by 13 C-substitution, the isotope affect on the internal conversion rate would be the same as previously observed and predicted by the energy gap law.…”

Section: Implications For the Mechanism Of Ic And Ground-state Ivrmentioning

confidence: 99%

Vibrational Relaxation in β-Carotene Probed by Picosecond Stokes and Anti-Stokes Resonance Raman Spectroscopy

2002

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Picosecond time-resolved Stokes and anti-Stokes resonance Raman spectra of all-trans-β-carotene are obtained and analyzed to reveal the dynamics of excited-state (S 1 ) population and decay, as well as ground-state vibrational relaxation. Time-resolved Stokes spectra show that the ground state recovers with a 12.6 ps time constant, in agreement with the observed decay of the unique S 1 Stokes bands. The anti-Stokes spectra exhibit no peaks attributable to the S 1 (2A g − ) state, indicating that vibrational relaxation in S 1 must be nearly complete within 2 ps. After photoexcitation there is a large increase in anti-Stokes scattering from ground-state modes that are vibrationally excited through internal conversion. The anti-Stokes data are fit to a kinetic scheme in which the C=C mode relaxes in 0.7 ps, the C-C mode relaxes in 5.4 ps and the C-CH 3 mode relaxes in 12.1 ps. These results are consistent with a model for S 1 -S 0 internal conversion in which the C=C mode is the primary acceptor, the C-C mode is a minor acceptor, and the C-CH 3 mode is excited via intramolecular vibrational energy redistribution.

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The state energy and the displacements of the potential minima of the 2Ag− state in all-trans-β-carotene as determined by fluorescence spectroscopy

Cited by 70 publications

References 20 publications

Orbital optimization in the density matrix renormalization group, with applications to polyenes and β-carotene

Orbital optimization in the density matrix renormalization group, with applications to polyenes and β-carotene

Time-Resolved Two-Photon Spectroscopy of Photosystem I Determines Hidden Carotenoid Dark-State Dynamics

Vibrational Relaxation in β-Carotene Probed by Picosecond Stokes and Anti-Stokes Resonance Raman Spectroscopy

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