mass spectrum

A spectrum which is obtained when a beam of ions is separated according to the mass-to-charge (m z) ratios of the ionic species contained within it.
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 1550
See also:
Orange Book, p. 204
PAC, 1990, 62, 2167 (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2200