This is an atom, radical, molecule or molecular
moiety which has lost one of more electrons thereby attaining an electrically positive charge.
The use of the term
cation as an alternative is not recommended. The use of mass ion is not recommended.
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