This occurs when an ion/atom or ion/molecule reaction takes place in which the charge
on the ion is transferred to the neutral species without any
dissociation of either. Synonymous with charge-transfer
ionization.
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 1547