Table 1. Summary of All the Observed Ions from (H₂O)⁺₂ Dissociation Together With Their Relative Ion Yields^a.

fragment	signal (counts)	relative ion yield	EA (eV)	reaction channel:
				(H2O)+2 →
H3O+	1,933,751	0.541(42)	11.715	H3O+ + OH15,16,19
H2O+	630,492	0.176(11)	12.815	H2O+ + H2O15,16,19
			18.215	H2O+ + OH + H15
(H2O)+2	613,728	0.172(8)	11.715	H3O+···OH15,16,19
H+	213,905b	0.06(4)	19.215	H+ + H2O + OH15
OH+	114,390	0.032(8)	18.515	OH+ + H2O + H15
O+	24,235	0.0068(20)	21.7	O+ + H2O + 2H
H+2	13,947	0.0068(14)	21.7	H+2 + H2O + O
H218O+	10,225	0.0029(1)
H318O+	9268	0.0026(3)
O+2	6052	0.0017(3)	27.6	O+2 + 4H
HO+2	4206	0.0012(2)	29.2	HO+2 + 3H
(H2O–O)+	1792	0.0005(1)	32.616/33.0	(H2O–O)+ + 2H16
H+3	796	0.0002(3)	36.5	H+3 + HO2

^aOur estimated appearance energies E_A are shown in the fourth column in bold, alongside the previously reported appearance energies.^15,16 The last column shows previously reported and suggested fragmentation pathways producing the observed ions.

^bSignal contributions by fast nondetected H⁺ ions are expected to be below 5% of the integrated H⁺ signal.