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 trime thylamine photodissociation at 193 nm is determined by combining photoioniz ation detection with supporting G3 theoretical calculations. N(CH3)(2) prim ary products with very little internal energy show an experimentally observ ed ionization onset of 9.1 +/- 0.2 eV, but do not appear at the parent ion (m/e = 44). Instead, the parent ion is unstable and easily fragments to m/e = 42, where the signal is observed. N(CH3)(2) radicals with higher interna l energies undergo H-atom loss from the neutral to give CH2NCH3, which has an observed ionization onset at parent (m/e = 43) of < 9.3 eV. At slightly higher ionization energies, these secondary products also appear at m/e = 4 2 (where their appearance energy is roughly 9.8-9.9 eV, uncorrected for int ernal energy). Finally, N(CH3)(2) radicals with the highest internal energy in this study appear to undergo H-2 loss as neutrals, giving rise to a spe cies whose parent ion has m/e = 42. The ionization onset of this species at m/e = 42 is found to be in the range of 9.5-9.6 eV. (C) 2000 American Inst itute of Physics. [S0021-9606(00)01332-5].