“…More interesting routes have been found in the dissociations of aromatic molecular ions containing a heteroatom(s) such as N, O, P, S, As, etc. [4][5][6][7][8][9][10][11][12][13][14][15][16] For example, several dissociation pathways have been proposed for the metastable dissociations of three isomeric methylpyridine molecular ions, which include ring cleavage, expansion, and contraction. 12 The dissociations of three isomeric hydroxypyridine (HP) radical cations (Scheme 1), which are isoelectronic with the toluene cation, have been studied using mass spectrometry (MS) and theoretical means.…”