Chemistry in Acetonitrile-Water Films Induced by Slow (<15 eV)Electrons: Application to the Earth and Space Chemistry

Acetonitrile and water are molecules detected notonly in space but also in planetary atmospheres. On the Earth, thenitrile compound is emitted from biomass burning and can befound up to the stratosphere. Trapped in water ice cores, they maybe exposed to energetic particles, photons and secondary electrons,and contribute to the formation of complex organic molecules.Here, we show that methanol is the main product from theeffective reaction of low-energy (<15 eV) electrons withacetonitrile-waterfilms deposited on a substrate maintained at85 K. In this process, each of the molecules is decomposed by thecolliding electrons, producing respectively methyl and hydroxylradicals, which further recombine to form methanol, as supportedby density functional theory (DFT) calculations. In addition, wealso report production of a small amount of glycolonitrile, a key precursor of adenine. This information contributes to a bettercomprehension and description of chemistry of icy grains.