This refers to a process whereby gaseous molecules are ionized when they interact
with other internally excited gaseous molecules or molecular moieties. Chemi-
ionization and chemical
ionization are two terms which should not be used interchangeably.
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