Spectator hole

{
  "id": "MLC-T-CHM-011118",
  "term": "Spectator hole",
  "field": "Chemistry",
  "definition": "A vacancy created in an inner-shell electron orbital of an atom during an ionization process, which does not directly participate in the subsequent relaxation or fragmentation pathways being observed. This hole remains 'watching' the process without being directly involved in the electronic transitions or bond breaking events. It is often observed in photoemission spectroscopy.",
  "subject": "Analytical Chemistry",
  "see_also": [
    "photoemission"
  ],
  "references": [
    "PAC, 2020, 92, 1781. 'Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)' on page 1830 (https://doi.org/10.1515/pac-2019-0404)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/spectator-hole/"
}