An ion formed by interaction of two species, usually an ion and a molecule, and often
within the ion source, to form an ion containing all the
constituent atoms of one species as well as an additional atom or atoms.
Source:
PAC, 1991, 63, 1541
(Recommendations for nomenclature and symbolism for mass spectroscopy (including an
appendix of terms used in vacuum technology). (Recommendations 1991))
on page 1549