The
enthalpy (per
mole) required to break a given bond of some specific molecular entity by homolysis, e.g.
for

,
symbolized as

(cf. heterolytic
bond dissociation energy).
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1089
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2176