A process wherein a charged species interacts with a neutral reactant to produce either
chemically different species or changes in the
internal energy of one or both of the reactants. The contrasting expression ion/neutral reaction
is not ideal, simply because the word neutral is not a noun. However, any alternatives
such as ion/neutral species reaction are so clumsy as to mitigate against their general
acceptance
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 1556