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<p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other
alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N-
containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when
the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic
σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in
each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported.
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Soot inception: A DFT study of σ and π dimerization of resonantly stabilized aromatic radicals
