Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon anti-bunching

The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demons...

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Bibliographic Details
Published inNature communications Vol. 5
Main Authors Wientjes, E, Renger, J, Curto, A.G, Cogdell, R, Hulst, N.F., van
Format Journal Article
Published 2014
Subjects
dna
dynamics
energy-transfer
exciton delocalization
molecule fluorescence
nanoantennas
optical antennas
pigment-protein complexes
purple bacterial lh2
spectroscopy
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Summary:The nature of the highly efficient energy transfer in photosynthetic light-harvesting complexes is a subject of intense research. Unfortunately, the low fluorescence efficiency and limited photostability hampers the study of individual light-harvesting complexes at ambient conditions. Here we demonstrate an over 500-fold fluorescence enhancement of lightharvesting complex 2 (LH2) at the single-molecule level by coupling to a gold nanoantenna. The resonant antenna produces an excitation enhancement of circa 100 times and a fluorescence lifetime shortening to B20 ps. The radiative rate enhancement results in a 5.5-fold-improved fluorescence quantum efficiency. Exploiting the unique brightness, we have recorded the first photon antibunching of a single light-harvesting complex under ambient conditions, showing that the 27 bacteriochlorophylls coordinated by LH2 act as a nonclassical single-photon emitter. The presented bright antenna-enhanced LH2 emission is a highly promising system to study energy transfer and the role of quantum coherence at the level of single complexes.
ISSN:2041-1723
2041-1723