Characterization of nitrogen-containing radical products from the photodissociation of trimethylamine using photoionization detection

The outcome of neutral and photoionized N~CH3!2 primary products of trimethylamine photodissociation at 193 nm is determined by combining photoionization detection with supporting G3 theoretical calculations. N~CH3!2 primary products with very little internal energy show an experimentally observed ionization onset of 9.160.2 eV, but do not appear at the parent ion (m/e544). Instead, the parent ion is unstable and easily fragments to m/e542, where the signal is observed. N~CH3!2 radicals with higher internal energies undergo H-atom loss from the neutral to give CH2NCH3, which has an observed ionization onset at parent (m/e543) of ,9.3 eV. At slightly higher ionization energies, these secondary products also appear at m/e542 ~where their appearance energy is roughly 9.8–9.9 eV, uncorrected for internal energy!. Finally, N~CH3!2 radicals with the highest internal energy in this study appear to undergo H2 loss as neutrals, giving rise to a species whose parent ion has m/e542. The ionization onset of this species at m/e542 is found to be in the range of 9.5–9.6 eV. © 2000 American Institute of Physics. @S0021-9606~00!01332-5#