Determination of the absolute CH3 radical flux emanating from a methane electron cyclotron resonance plasma

Abstract

Methyl radicals from a methane electron cyclotron resonance plasma are measured quantitatively at the sample position by ionization-threshold mass spectrometry (ITMS). The absolute fluxes are determined by calibrating the CH3 ITMS results with those of methane, taking into account the published energy-dependent cross sections for the ionization of CH3 and CH4, respectively. The measured CH3 radical fluxes are on the order of some 1015 cm−2 s−1, which is in accordance with recent modeling results.