Rebuttal to the Comment on The role of methyl radicals in the reduction of NO by CH4 over a Ba/MgO catalyst [by A.Yu. Gladky, V.K. Ermolaev and V.N. Parmon]
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J.H. Lunsford et al. (1997, 1995, 1996) developed a technique known as variable ionization energy mass spectrometry to detect methyl radicals formed during the decomposition of azomethane or the catalytic reaction of methane with oxygen over metal oxides that promote the oxidative coupling of methane. The results of the technique were criticized (A.Y. Gladky et al. 1999). Whether the peak at 15 amu in a spectrum of a gas mixture obtained at an electron-impact energy of 19 ev results from methyl radicals is questioned, based on ionization cross sections. It is argued that at an electron impact energy of 19 ev, the ionization cross sections for the reactions CH 4 CH 4+ + e - and CH 4 CH 3+ + H + e - would be so large that one could not detect methyl radicals in a gas mixture containing 1% CH 3 in CH 4 and concluded that the actual electron impact energy is close to 19 ev. These conclusions are refuted. Only nominal electron energies were reported, i.e., the values reported could have differed fro the actual energies by several electron volts.
author list (cited authors)
Lunsford, J. H., Rosynek, M. P., & Xie, S.
complete list of authors
Lunsford, Jack H||Rosynek, Michael P||Xie, Shuibo