Proposed solid-state reaction scheme of C₂H₂interacting with H-atoms and OH–radicals. Solid arrows indicate reaction pathways confirmed or suggested in this work; black lines represent H-atom reactions and blue lines represent OH-radical addition reactions. Dashed arrows indicate other possible reactionpathways which could also lead to the investigated COMs. VA: vinyl alcohol; AC: acetaldehyde; Ket: ketene; Eth: ethanol; AA: acetic acid.