Editing Mass spectrum (section)

===Alternative x-axis notations===
There are several alternatives to the standard ''m/z'' notation that appear in the literature; however, these are not currently accepted by standards organizations and most journals.  ''m/e'' appears in older historical literature. A label more consistent with the [[IUPAC green book]] and [[ISO 31]] conventions is ''m/Q'' or ''m/q'' where ''m'' is the symbol for mass and ''Q'' or ''q'' the symbol for charge with the units u/e or Da/e. This notation is not uncommon in the physics of mass spectrometry but is rarely used as the abscissa of a mass spectrum. It was also suggested to introduce a new unit [[Thomson (unit)|thomson]] (Th) as a unit of ''m/z'', where 1 Th = 1 u/e.<ref>Cooks, R. G. and A. L. Rockwood (1991). "The 'Thomson'. A suggested unit for mass spectroscopists." Rapid Communications in Mass Spectrometry 5(2): 93.</ref> According to this convention, mass spectra x axis could be labeled ''m/z'' (Th) and negative ions would have negative values. This notation is rare and not accepted by [[IUPAC]] or any other standards organisation.