“…A similar model was described briefly in [11,14], where the influence of oxygen addition to Ar : He : CH 2 , where D-diffusion coefficient, r-tube radius) for I, O atoms and CH 3 radicals in Ar mixtures were equal to ~300, 800 and 630 s −1 , and in He-900, 1600 and 1400 s −1 , correspondingly. The probability of surface recombination for I atoms, CH 3 and O was chosen to be 1, although there are indications that on a clean surface for I atoms it might be considerably smaller [46] down to 10 −3 ÷ 10 −4 .…”