Metastable state

{
  "id": "MLC-T-CHM-007268",
  "term": "Metastable state",
  "field": "Chemistry",
  "definition": "An excited quantum state of an atomic nucleus, atom, or molecule that has a significantly longer lifetime than ordinary excited states. Although it is not the state of lowest energy, a system in a metastable state requires an input of energy to transition to a lower energy state or the ground state. The decay of a metastable nuclear isomer is known as an isomeric transition, which can result in the emission of gamma rays or conversion electrons.",
  "synonyms": [
    "metastable"
  ],
  "subject": "Analytical Chemistry",
  "see_also": [
    "ground state",
    "isomeric state",
    "excited state",
    "lifetime",
    "metastable ion",
    "transient species"
  ],
  "references": [
    "PAC, 1982, 54, 1533. 'Glossary of terms used in nuclear analytical chemistry (Provisional)' on page 1546 (https://doi.org/10.1351/pac198254081533)",
    "PAC, 1985, 57, 1453. 'Nomenclature, symbols, units and their usage in spectrochemical analysis - V: Radiation sources (Recommendations 1985)' on page 1463 (https://doi.org/10.1351/pac198557101453)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/metastable-state/"
}