Abstract
High resolution and metastable decomposition spectra of the ions [M + NH4]+ (and [M + ND4]+) formed by reaction of [NH4]+ (and [ND4]+) with cyclohexanone have been measured. The results provide evidence that the m/z 98 ion, which is abundant in the chemical ionization (NH3) spectrum of cyclohexanone, is in fact composed of two isobaric ions: a protonated imine ion and the molecular ion of cyclohexanone. The former is formed by a mechanism analogous to that occurring in solution.