Absolute photoionization cross section of the methyl radical.

The absolute photoionization cross section of the methyl radical was determined relative to that of NO at photon energies of 10.54 eV using the CH(3) + NO(2) --> CH(3)O + NO reaction. Kinetics of this reaction was studied in a fast flow reactor coupled with VUV laser photoionization. Simulation of the kinetics of the decrease of the methyl signal and the corresponding increase of the NO signal (in combination with the NO absolute photoionization cross section determined by Watanabe (Watanabe, K. J. Chem. Phys. 1954, 22, 1564; Watanabe, K.; Matsunaga, F. M.; Sakai, H. Appl. Opt. 1967, 6, 391)), yields the absolute photoionization cross section of the methyl radical: sigma(CH(3))(10.54 eV) = 5.1 (1.2) x 10(-18) cm(2) (95% confidence interval). This result is in good agreement with the recently published measurements by Taatjes et al. (Taatjes, C. A.; Osborn, D. L.; Selby, T. M.; Meloni, G.; Fan, H.; Pratt, S. T. J. Phys. Chem. A 2008, 112, 9336) and by Gans et al. (Gans, B.; Mendes, L. A. V.; Boyé-Péronne, S.; Douin, S.; Garcia, G.; Soldi-Lose, H.; Cunha de Miranda, B. K.; Alcaraz, C.; Carrasco, N.; Pernot, P.; Gauyacq, D. J. Phys. Chem. A 2009, 114, 3237).