cluster ion

in mass spectrometry
https://doi.org/10.1351/goldbook.C01115
An ion formed by the combination of more ions or atoms or molecules of a chemical species often in @A00472@ with a second species. For example, [(H2O)nH]+ is a @CT06769@ ion.
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 [Terms] [Paper]