Desorption traces of N₂ and ¹³CO in H₂O:CO₂:N₂ and H₂O:CO₂:¹³CO ices respectively as a function of temperature during the TPD. Top row: desorption traces of N₂, (solid, blue), CO₂ (grey, dotted) and H₂O (grey, dashed) for different ice experiments. For the presented data the N₂ contribution has been calculated to be between 3% and 5% with respect to water, therefore assumed to be relatively constant. The CO₂ contribution is shown at the top with respect to water and increases from left to right. For N₂, the corrected data have been calculated from the m/z = 14 data, corresponding to the N fragment, as described in Appendix B, therefore resulting in more noise than the ¹³CO data. Neither the CO₂ nor the H₂O data have been corrected or baseline subtracted for this plot. Bottom row: desorption trace for m/z = 29 (¹³CO, orange) for different ice experiments, with the CO₂ and H₂O desorption traces shown as well. The ¹³CO contributions have been calculated to be between 3% and 4% with respect to water, except for the first experiment, in which the ¹³CO has been calculated to be ∼2.5%. The ¹³CO signal has been corrected and baseline subtracted, whereas for the CO₂ and H₂O traces no corrections have been performed. Please note that for the ¹³CO measurements, the background pressure has been higher than for the N₂ measurements, resulting in a larger background for H₂O and CO₂.