Ultrafast coherent energy transfer

Gregory D. ScholesDepartment of Chemistry, University of Toronto

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Alumni:

Karyn AngDr. Vitalij KovalevskijDr. Peggy HinesDr. Alexander DoustDr. Xiujuan YangDr. Karolina FritzDr. Sree NairDr. Sandeep KumarDr. Mayrose SalvadorDr. Tieneke DykstraDr. Elisabetta ColliniDr. Tihana Mirkovic

Collaborators:

National Renewable Energy LaboratoryGarry Rumbles

Università di PisaBenedetta Mennucci

University of New South WalesPaul CurmiKrystyna Wilk

University of MonsDavid Beljonne

University of HoustonEric Bittner

e group now:

Yasser HassanVanessa HuxterYaser KhanAnna LeeShun LoMichelle NagyMegan OhCathy Wong

Dr. John CaseyDr. Carles CurutchetDr. Jun HeDr. Marcus JonesDr. Jeongho KimDr. Haizheng Zhong

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J. Perrin, F. Perrin, S.I. Vavilov

H. Kallmann & F. London; Ya. Frenkel

Vavilov & Galanin

Emerson & Arnold

Th. Förster

FRET

• Observed concentration quenching of dye fluorescence

• Proposed a quantum mechanical coupling between donor and acceptor

• Energy migration depolarizes fluorescence• Spectral overlap condition

• FRET in biological systems

• Quantum mechanical coupling + spectral overlap

1923–29

1929

1940s

1932

1948

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J. Phys. Chem. B 113, 6583–6599 (2009).

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Natural PV: photosynthesisemploys specialized energy

funnels

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Birstonas, Lithuania September 1996

ESF Workshop (Valkunas and van Grondelle)

“... The discovery of these structures has strongly stimulated the analysis of the physical processes responsible for the rapid migration of energy in photosynthesis”

“Major questions concern...time over which the excitation must be considered as coherent...”

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Nature, 431, 256–257 (2004).

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Natural nanoscale systems

Elisabetta Collini, Carles, Curutchet, et al. Proceedings from the Paris Research Center Workshop on Energy Flow Dynamics in Biomaterial Systems (2008).

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Light-harvesting in nature

Elisabetta Collini (2008)

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Cryptophyte marine algae

flagella

ejectosome

gullet

periplast

Rhodomonas CS24

Tihana Mirkovic, et al. Photosynthesis Res. (2009).

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Rhodomonas CS24 (a cryptophyte)

Alexander Doust, et al. J. Mol. Biol. (2004)

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Structural model of PC645 (Chroomonas)

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Assign the spectrum to structure

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Assign the spectrum to structure

DBV

PCB

MBV

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Coherence in cross-peak beats

!+ =1!2

!A!B + AB!"

!! =1!2

!A"B "AB""

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Electronic beats

!+ =1!2

!A!B + AB!"

!! =1!2

!A"B "AB""

A!, B!

!!=1 = ca!a + cb!b + cc!c

!!=1ab = cac!b

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Need information at the amplitude level

population/polarization grating

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τ T

Two-dimensional photon echo (2DPE)

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Interpreting 2DPE data

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Rephasing vs. non-rephasing signals

Yuan-Chung Cheng & Graham Fleming

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Coherence pathways in the signals

Yuan-Chung Cheng & Graham Fleming

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2DPE signals (real part) decomposed

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2D-2PE (real part) PC645 antenna 293K

from the left top to the right bottom T=0, 6, 10, 20, 30, 40,50, 70, 80, 90, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 500, 600, 700, 800, 900 fs, 1ps, 2ps, 5ps.

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Electronic beats: rephasing spectra

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Electronic beats

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Electronic beats: rephasing spectra

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Coherence beats (PC645): non-rephasing

2.11 eV

2.185 eV

2.06 eV

2.11 eV

2.185 eV2.06 eV

~600 cm–1

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Coherence beats (PC645): non-rephasing

2.11 eV

2.185 eV

2.06 eV

2.11 eV

2.185 eV2.06 eV

2.11 eV

2.185 eV

2.06 eV

~600 cm–1

~380 cm–1

2.11 eV

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Coherently ‘wired’ energy migration

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Quantum probability amplitudes

Classical: P = P(d-a) + P(d1-d2-a) + ...

Quantum: P = | G(d-a) + G(d1-d2-a) + ... |2

Time (ps)

R. P. Feynman, Rev. Mod. Phys. (1948).

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Weak and strong coupling regimes

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Limits of the dynamics

Förster theory Redfield theory, etc

weak electronic coupling

strong electronic coupling

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PC645 trajectories: weak coupling to MBV

18.0

17.5

17.0

16.5

16.0

x103

1000080006000400020000

-0.4-0.3-0.2-0.10.0

1000080006000400020000

Ener

gy

Time (fs)

E!=1

E!=2

E!=3

!!=1 = ca!a + cb!b + cc!c

!!=1ab = cac!b

!!=1ab

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PC645 trajectories

18.0

17.5

17.0

16.5

16.0

x103

1000080006000400020000

-0.4-0.3-0.2-0.10.0

1000080006000400020000

Ener

gy

Time (fs)

!!=1ab

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What limits the exciton diffusion length?

ultrafast energyrelaxation/transfer

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Energy migration along a PPV chain

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Energy transfer in PPV chains

Jay Singh, Eric Bittner, David Beljonne, GDS (2009).

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Ultrafast anisotropy decay

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Photon echo spectroscopy

population/polarization grating

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Coherence-mediated energy transfer

293 K

Elisabetta Collini & GDS, Science 323, 369–373 (2009). J Phys Chem A 113, 4223–4241 (2009).

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