Desorption behaviour of m/z = 29 (¹³CO, orange), CO₂ (grey, dotted), and H₂O (grey, dashed). Both the ¹³CO and CO₂ data have been corrected for the fractionation, for H₂O this was not necessary. The data was not baseline corrected for the display, but baseline subtraction was performed for further analysis. The figure titles correspond to the theoretical mixing ratio in the gas mixing system.