The ratio of the maximum ion current recorded at a mass \(m\) to the ion current arising from the same species recorded at an adjacent mass (\(m\pm 1\)).
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 1554 [Terms] [Paper]