REACTIVITY BETWEEN A CO-CONTAINING ICE AND NON-ENERGETIC OH RADICALS

Reactions between a CO/CO2 mixture and non-energetic OH radicals were carried out at 3.5 K. The temperature was kept low in order to characterize the reactivity step by step and to avoid side reactions. The hydroxyl radicals originate from discharged H2O/He mixtures. The abundance of the products was monitored in situ using a Fourier transform infrared spectrometer. As already reported, the formation of CO2 was clearly observed. Additionally, we show the co-formation of H2O, HO2, and H2CO when the CO/CO2 mixture is co-injected with OH radicals. Furthermore, neither HO2 nor H2CO was observed when very small amounts of CO are co-injected with an excess of OH radicals. The study of concentration effects suggests that HO2 and H2CO species are directly due to the primary reactions between CO and OH radicals, and not the side processes.