Formation of NH2CHO and CH3CHO upon UV processing of interstellar ice analogs

Complex organic molecules (COMs) may have played a role in the formation of life in the early Earth (Herbst & van Dishoeck (2009)). Here we present the formation of NH₂CHO and CH₃CHO upon vacuum-ultraviolet (VUV) irradiation of CO:NH₃ and CO:CH₄ ice mixtures, simulating the UV processing of interstellar ices in the interior of dense clouds. We have found that the conversion from ${{N}}{{{H}}_{\dot 2}}$ radicals to NH₂CHO is 4-15 times higer than that from ${{N}}{{{H}}_{\dot 3}}$ to CH₃CHO, probably due to the competing formation of larger hydrocarbons in the latter case.