a) TPD curve of the m/z = 30 mass fragment, corresponding to the molecular ion of H₂CO, after irradiation in experiment 3 (red) compared to the blank (black). A desorption peak at ~112 K (dashed line) confirms the formation of formaldehyde. b) TPD curve of the m/z = 31 mass fragment, corresponding to the molecular ion of HCO, after irradiation in experiment 7 (red) compared to the blank (black). A desorption peak at ~113 K (dashed line) confirms the formation of formaldehyde.