Third body

{
  "id": "MLC-T-CHM-013654",
  "term": "Third body",
  "field": "Chemistry",
  "definition": "A species, denoted as M, that participates in a bimolecular or unimolecular chemical reaction by colliding with the reacting species without undergoing a chemical change itself. Its role is to either supply energy to a reactant to enable a reaction or to remove excess energy from a newly formed product to stabilize it. In recombination reactions, for example, the third body carries away the energy released upon bond formation, preventing the immediate dissociation of the product.",
  "subject": "Physical and Biophysical Chemistry",
  "see_also": [
    "chaperon",
    "molecularity"
  ],
  "references": [
    "PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 189 (https://doi.org/10.1351/pac199668010149)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/third-body/"
}