title: Strong antenna-enhanced fluorescence of a single light-harvesting complex shows photon antibunching.
abstract: 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 light-harvesting 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 ~20 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 non-classical 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.
authors: ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain.
authors: Emilie
authors: E
authors: Wientjes
authors: ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain.
authors: Jan
authors: J
authors: Renger
authors: 1] ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain [2] Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA.
authors: Alberto G
authors: AG
authors: Curto
authors: Institute of Biomedical and Life Sciences, University of Glasgow, Biomedical Research Building, Glasgow G12 8QQ, UK.
authors: Richard
authors: R
authors: Cogdell
authors: 1] ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain [2] ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain.
authors: Niek F
authors: NF
authors: van Hulst
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004735:Energy Transfer; D005453:Fluorescence; D006046:Gold / Q000737:chemistry; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D049329:Nanostructures / Q000737:chemistry*; D017785:Photons; D012241:Rhodopseudomonas / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D006046:Gold