{
  "id": "2301.03916",
  "version": "v1",
  "published": "2023-01-10T11:38:27.000Z",
  "updated": "2023-01-10T11:38:27.000Z",
  "title": "External screening and lifetime of exciton population in single-layer ReSe$_2$ probed by time- and angle-resolved photoemission spectroscopy",
  "authors": [
    "Klara Volckaert",
    "Byoung Ki Choi",
    "Hyuk Jin Kim",
    "Deepnarayan Biswas",
    "Denny Puntel",
    "Simone Peli",
    "Fulvio Parmigiani",
    "Federico Cilento",
    "Young Jun Chang",
    "Søren Ulstrup"
  ],
  "comment": "6 pages, 4 figures",
  "categories": [
    "cond-mat.mes-hall",
    "cond-mat.mtrl-sci"
  ],
  "abstract": "The semiconductor ReSe$_2$ is characterized by a strongly anisotropic optical absorption and is therefore promising as an optically active component in two-dimensional heterostructures. However, the underlying femtosecond dynamics of photoinduced excitations in such materials has not been sufficiently explored. Here, we apply an infrared optical excitation to single-layer ReSe$_2$ grown on a bilayer graphene substrate and monitor the temporal evolution of the excited state signal using time- and angle-resolved photoemission spectroscopy. We measure an optical gap of $(1.53 \\pm 0.02)$ eV, consistent with resonant excitation of the lowest exciton state. The exciton distribution is tunable via the linear polarization of the pump pulse and exhibits a biexponential decay with time constants given by $\\tau_1 = (110 \\pm 10)$ fs and $\\tau_2 = (650 \\pm 70)$ fs, facilitated by recombination via an in-gap state that is pinned at the Fermi level. By extracting the momentum-resolved exciton distribution we estimate its real-space radial extent to be greater than 17.1 \\AA, implying significant exciton delocalization due to screening from the bilayer graphene substrate.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2023-01-10T11:38:27.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "angle-resolved photoemission spectroscopy",
      "single-layer rese",
      "exciton population",
      "bilayer graphene substrate",
      "external screening"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 6,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}