The vinyloxonium cation, $${\rm CH}_{\rm 2} = {\rm CH - }\mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2}$$, a stable [C2H5O]+ species in the gas phase

Abstract The charge stripping mass spectra of [C 2 H 5 O] + ions permit the clear identification of four distinct species: $${\rm CH}_{\rm 3} - {\rm O - }\mathop {\rm C}\limits^{\rm + } {\rm H}_{\rm 2}$$ , $${\rm CH}_{\rm 3} - \mathop {\rm C}\limits^{\rm + } {\rm H - OH}$$ , and $${\rm CH}_{\rm 2} = {\rm CH - }\mathop {\rm O}\limits^{\rm + } {\rm H}_{\rm 2}$$ . The latter, the vinyloxonium ion, has not been identified before. It is generated from ionized n ‐butanol and 1,3‐propanediol. Its heat of formation is estimated to be 623±12 kJ mol −1 . The charge stripping method is more sensitive to these ion structures than conventional collisional activation, which focuses attention on singly charged fragment ions.