Left panel: infrared features of pure propanal (exp. 2.3) and 1-propanol (exp. 2.0). Right panel: RAIRS annealing series of propanal + H (exp. 2.1), taken after deposition at 10 K. We note that the features at 860 cm⁻¹ and 969 cm⁻¹ are signatures of propanal and newly formed 1-propanol (tentative), as the signatures disappear by 125 K (propanal peak desorption temperature) and 155 K (1-propanol peak desorption temperature), respectively. RAIR spectra are offset for clarity.