{
  "id": 11143512,
  "title": "Exciton wavefunctions come into view",
  "url": "https://urgent.news/2026/10/01/exciton-wavefunctions-come-into-view",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-01T08:00:42.000Z",
  "source": {
    "name": "Physics World",
    "slug": "physics-world",
    "url": "https://physicsworld.com/a/exciton-wavefunctions-come-into-view/"
  },
  "original_language": "en",
  "account": "Physicists have, for the very first time, visually mapped the quantum probability distribution of an exciton thanks to a cutting-edge technique called time-resolved photoemission orbital tomography (trPOT). By simultaneously observing the spatial and momentum distributions of these fleeting quasiparticles, the research team from Austria, Germany, and elsewhere gained new insights into how excitons behave in complex materials. This breakthrough could pave the way for improvements in organic photovoltaic devices that convert light into electricity.\n\nWhen light interacts with materials like insulators and semiconductors, photons can boost electrons to higher energy levels, generating positively charged holes. These electron-hole pairs combine to form neutral excited quasiparticles known as excitons. Although excitons play a crucial role in light harvesting for optoelectronics, their intricate quantum mechanical nature has been challenging to study, primarily because the electrons revert to their original state within picoseconds (10^-12 seconds), which is faster than what typical spectroscopic methods can handle.\n\nTo overcome this limitation, the researchers utilized trPOT, combining ultrafast photoemission spectroscopy with momentum microscopy. This approach allowed them to resolve the exciton wavefunction at the femtosecond (fs, 10^-15 seconds) scale, ideal for capturing the rapid changes in the exciton's structure.\n\nIn their experiment, Peter Puschnig and colleagues from the University of Graz in Austria used an ultrashort laser pulse with 2.35 eV energy on an organic semiconductor called alpha-sexithiophene, commonly used in optoelectronic devices. The pulse created the excitons, which were then studied by ejecting the electrons using a second, higher-energy laser pulse of 21.7 eV – a process called photoemission.\n\nBy measuring the ejected electrons' energy and direction, as well as varying the time between the first and second laser pulses, the team obtained snapshots of the exciton at various time intervals post-creation. They found that the exciton initially spans about 1.5 nm, roughly three molecules, but contracts by around 25% within just 400 fs of its formation.\n\nThis achievement marks a significant step forward in understanding the quantum mechanical behavior of excitons, offering a real-time view of their spatial structure and phase. The research, published in Physical Review X, not only presents a novel method for studying excitons in real space but also provides valuable insights into how excited states evolve into charge-separated states in donor/acceptor systems, which are essential for organic photovoltaics.\n\nIn the future, the researchers aim to study more complex systems to understand better how molecular and electronic structures control charge separation processes. These advancements could ultimately contribute to enhancing the efficiency of solar cells by optimizing the charge separation after photon absorption.",
  "summary": "New work could lead to improvements in organic photovoltaics The post Exciton wavefunctions come into view appeared first on Physics World .",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}