Photosynthetic Light Harvesting by Carotenoids: Detection of an Intermediate Excited State

Cerullo, Giulio; Polli, Dario; Lanzani, Guglielmo; Silvestri, S. De; Hashimoto, Hideki; Cogdell, Richard J.

doi:10.1126/science.1074685

Cited by 264 publications

(220 citation statements)

References 22 publications

Supporting

Mentioning

196

Contrasting

Order By: Relevance

“…[5][6][7] In recent years it has become clear that this two excited-state levels representation is incomplete: additional electronic states that lie below S 2 have been theoretically predicted; 5 experimental evidence for some of them has been presented by several workers. [8][9][10][11][12] The S* state was discovered some years ago in spirilloxanthin, both in solution and bound to the light-harvesting (LH1) complex of Rhodospirillum rubrum. 9 It is characterized by an excited-state absorption (ESA) band blue-shifted with respect to that of the S 1 f S n absorption but red-shifted with respect to the optically allowed S 0 f S 2 transition.…”

Section: Introductionmentioning

confidence: 99%

Energy Transfer, Excited-State Deactivation, and Exciplex Formation in Artificial Caroteno-Phthalocyanine Light-Harvesting Antennas

et al. 2007

View full text Add to dashboard Cite

We present results from transient absorption spectroscopy on a series of artificial light-harvesting dyads made up of a zinc phthalocyanine (Pc) covalently linked to carotenoids with 9, 10, or 11 conjugated carboncarbon double bonds, referred to as dyads 1, 2, and 3, respectively. We assessed the energy transfer and excited-state deactivation pathways following excitation of the strongly allowed carotenoid S 2 state as a function of the conjugation length. The S 2 state rapidly relaxes to the S* and S 1 states. In all systems we detected a new pathway of energy deactivation within the carotenoid manifold in which the S* state acts as an intermediate state in the S 2 f S 1 internal conversion pathway on a sub-picosecond time scale. In dyad 3, a novel type of collective carotenoid-Pc electronic state is observed that may correspond to a carotenoid excited state(s)-Pc Q exciplex. The exciplex is only observed upon direct carotenoid excitation and is nonfluorescent. In dyad 1, two carotenoid singlet excited states, S 2 and S 1 , contribute to singlet-singlet energy transfer to Pc, making the process very efficient (>90%) while for dyads 2 and 3 the S 1 energy transfer channel is precluded and only S 2 is capable of transferring energy to Pc. In the latter two systems, the lifetime of the first singlet excited state of Pc is dramatically shortened compared to the 9 double-bond dyad and model Pc, indicating that the carotenoid acts as a strong quencher of the phthalocyanine excited-state energy.

show abstract

Section: Introductionmentioning

confidence: 99%

Energy Transfer, Excited-State Deactivation, and Exciplex Formation in Artificial Caroteno-Phthalocyanine Light-Harvesting Antennas

et al. 2007

View full text Add to dashboard Cite

show abstract

“…According to the PAS, transitions between states of identical PAS symmetry (such as the 1A − g ground state and the 1B − u excited state) are strictly dipole-forbidden and, correspondingly, many authors erroneously were misled to think that this peculiar property of ZDO models is valid also in actual polyenes (see, e.g., the discussions on p. 2397 in Ref. 24). However, since 1998 several authors [25][26][27] have demonstrated that the 1B − u states actually carry small transition dipole moments.…”

Section: A Theory Of π-Electron Excitations In Long Polyenesmentioning

confidence: 99%

“…It took more than a decade until the quoted prediction was verified experimentally 24,34 and it has been frequently emphasized that the intermediate covalent states of the carotenoids (e.g., 1B − u ,3A − g ) can support the efficient energy transfer to the chlorophylls in the light harvesting process of photosynthesis. 21,23,35 It may be, however, that the presence of the 1B − u singlet state below the 1B + u state has been actually observed in pure polyenes much earlier.…”

Section: B Development Of Polyene Spectroscopymentioning

confidence: 99%

Electronic excitations in long polyenes revisited

Schmidt

Tavan

2012

The Journal of Chemical Physics

106

View full text Add to dashboard Cite

We apply the valence shell model OM2 [W. Weber and W. Thiel, Theor. Chem. Acc. 103, 495, (2000)] combined with multireference configuration interaction (MRCI) to compute the vertical excitation energies and transition dipole moments of the low-energy singlet excitations in the polyenes with 4 ≤ N ≤ 22π -electrons. We find that the OM2/MRCI descriptions closely resemble those of Pariser-Parr-Pople (PPP) π -electron models [P. Tavan and K. Schulten, Phys. Rev. B 36, 4337, (1987)], if equivalent MRCI procedures and regularly alternating model geometries are used. OM2/MRCI optimized geometries are shown to entail improved descriptions particularly for smaller polyenes (N ≤ 12), for which sizeable deviations from the regular model geometries are found. With configuration interaction active spaces covering also the σ -in addition to the π -electrons, OM2/MRCI excitation energies turn out to become smaller by at most 0.35 eV for the ionic and 0.15 eV for the covalent excitations. The particle-hole (ph) symmetry, which in Pariser-Parr-Pople models arises from the zero-differential overlap approximation, is demonstrated to be only weakly broken in OM2 such that the oscillator strengths of the covalent 1B − u states, which artificially vanish in ph-symmetric models, are predicted to be very small. According to OM2/MRCI and experimental data the 1B − u state is the third excited singlet state for N < 12 and becomes the second for N ≥ 14. By comparisons with results of other theoretical approaches and experimental evidence we argue that deficiencies of the particular MRCI method employed by us, which show up in a poor size consistency of the covalent excitations for N > 12, are caused by its restriction to at most doubly excited references.

show abstract

“…During photochemical reactions in protein environment, one often faces the problem that large amounts of energy are dissipated on very short length and timescales [1][2][3]. A similar situation arises in molecular electronic devices [4].…”

Section: Introductionmentioning

confidence: 99%

Vibrational energy transport in the presence of intrasite vibrational energy redistribution

Schade

Hamm

2009

The Journal of Chemical Physics

View full text Add to dashboard Cite

Vibrational energy transport in the presence of intrasite vibrational energy redistribution AbstractThe mechanism of vibrational energy flow is studied in a regime where a diffusion equation is likely to break down, i.e., on length scales of a few chemical bonds and time scales of a few picoseconds. This situation occurs, for example, during photochemical reactions in protein environment. To that end, a toy model is introduced that on the one hand mimics the vibrational normal mode distribution of proteins, and on the other hand is small enough to numerically time propagate the system fully quantum mechanically. Comparing classical and quantum-mechanical results, the question is addressed to what extent the classical nature of the molecular dynamics simulations (which would be the only choice for the modeling of a real molecular system) affects the vibrational energy flow mechanism. Small differences are found which are due to the different ways classical and quantum mechanics distribute thermal energy over vibrational modes. In either case, a ballistic and a diffusive phase can be identified. For these small length and time scales, the latter is governed by intrasite vibrational energy redistribution, since vibrational energy does not necessarily thermalize completely within individual peptide units. Overall, the model suggests a picture that unifies many of the observations made recently in experiments.Vibrational energy transport in the presence of intra-site vibrational energy redistribution Marco Schade and Peter HammPhysikalisch-Chemisches Institut, Universität Zürich, Winterthurerstr. 190, CH-8057 Zürich, Switzerland (Dated: September 16, 2009) The mechanism of vibrational energy flow is studied in a regime where a diffusion equation is likely to break down, i.e. on length scales of a few chemical bonds and timescales of a few picoseconds. This situation occurs for example during photochemical reactions in protein environment. To that end, a toy model is introduced that on the one hand mimics the vibrational normal mode distribution of proteins, and on the other hand is small enough to numerically time-propagate the system fully quantum-mechanically. Comparing classical and quantum-mechanical results, the question is addressed to what extent the classical nature of the molecular dynamics simulations (which would be the only choice for the modelling of a real molecular system) affects the vibrational energy flow mechanism. Small differences are found which are due to the different ways how classical and quantum mechanics distribute thermal energy over vibrational modes. In either case, a ballistic and a diffusive phase can be identified. For these small length and timescales, the latter is governed by intra-site vibrational energy redistribution, since vibrational energy does not necessarily thermalize completely within individual peptide units. Overall, the model suggests a picture that unifies many of the observations made recently in experiments.

show abstract

Photosynthetic Light Harvesting by Carotenoids: Detection of an Intermediate Excited State

Cited by 264 publications

References 22 publications

Energy Transfer, Excited-State Deactivation, and Exciplex Formation in Artificial Caroteno-Phthalocyanine Light-Harvesting Antennas

Energy Transfer, Excited-State Deactivation, and Exciplex Formation in Artificial Caroteno-Phthalocyanine Light-Harvesting Antennas

Electronic excitations in long polyenes revisited

Vibrational energy transport in the presence of intrasite vibrational energy redistribution

Contact Info

Product

Resources

About