Ultrafast spectroscopic imaging of exfoliated graphene

Authors

  • Giulia Grancini,

    1. Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133 Milano, Italy
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  • Nicola Martino,

    1. Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133 Milano, Italy
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  • Massimiliano Bianchi,

    1. L-NESS, Department of Physics, Polo di Como, Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
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  • Laura Giorgia Rizzi,

    1. L-NESS, Department of Physics, Polo di Como, Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
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  • Valeria Russo,

    1. Department of Energetics, Politecnico di Milano, Via Lambruschini 4, 20156 Milano, Italy
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  • Andrea Li Bassi,

    1. Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133 Milano, Italy
    2. Department of Energetics, Politecnico di Milano, Via Lambruschini 4, 20156 Milano, Italy
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  • Carlo Spartaco Casari,

    1. Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133 Milano, Italy
    2. Department of Energetics, Politecnico di Milano, Via Lambruschini 4, 20156 Milano, Italy
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  • Annamaria Petrozza,

    1. Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133 Milano, Italy
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  • Roman Sordan,

    1. L-NESS, Department of Physics, Polo di Como, Politecnico di Milano, Via Anzani 42, 22100 Como, Italy
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  • Guglielmo Lanzani

    Corresponding author
    1. Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133 Milano, Italy
    • Phone: +39 02 2399 9872, Fax: +39 02 2399 6126
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Abstract

In this paper we investigate the carrier cooling dynamics in graphene flakes exploiting ultrafast transient absorption imaging technique. This tool enables us to combine nanoscale spatial resolution and sub-picosecond (ps) time resolution. It provides many advantages over the standard transient absorption techniques because it directly investigates the excited state dynamics at a local scale that would be usually averaged out. The local dynamics show a photobleaching recovery in the first ps, assigned to cooling by electron–phonon scattering. We found that the photoexcited carrier dynamics is spatially uniform over the micrometer-sized exfoliated graphene layer.

original image

Ultrafast pump–probe technique is combined with an optical microscope to investigate the local excited state dynamics in graphene flakes.

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