¹³CO₂ yield as a function of surface temperature during deposition of 0.5 ML of ¹³CO + O. Circles represent the integrated area under the TPD curves of mass 45 after a deposition of 0.5 ML of ¹³CO + O on ASW ice held at different temperatures (10 K, 20 K, 30 K, 35 K, 40 K, 45 K, 50 K, 60 K). The solid line is a fit of the area behaviour. The TPD peaks (obtained at T_surface = 20 K) added in the figure show when O₂ and ¹³CO desorb, and this helps interpret the ¹³CO₂ yield behaviour with temperature.