This work examines how to estimate an effective O(3P) surface recombination probability \(\gamma _\textrm{O}\) in CO2 plasmas in Pyrex from the temporal evolution of its density, measured in modulated current conditions in DC glow discharges. Zero-dimensional simulations are used under steady-state and current modulation conditions to analyse experimental data available for pressures in the range 0.2–5 Torr and currents between 10 and 50 mA. It is shown that the estimation of \(\gamma _\textrm{O}\) is simpler in CO2 than in O2, as in the former case it can be realistically estimated by assuming that the net losses of O(3P) correspond to surface recombination losses only, while in the latter case volume recombination and flow losses have to be additionally taken into account. The main reason for this difference is the lower fraction of oxygen species in CO2 plasmas, leading to much lower volume recombination rates.
