Desorption from Methanol and Ethanol Ices by High Energy Electrons: Relevance to Astrochemical Models

Abstract

Methanol and ethanol, precursors of prebiotic molecules, are found in interstellar and circumstellar environments. At low temperatures, electrons may interact with these frozen molecules on dust grain surfaces stimulating desorption of atomic and molecular ions and charged clusters. These heavy fragments released from the icy mantles could contribute to the abundance in the gas phase of organic molecules in such environments. In this work, we investigate the ionic fragments desorbed from methanol and ethanol pure ices due to high energy electron impact. Absolute desorption yields (ions/impact) for each fragment desorbed from the ice surface were determined. Several clusters and heavier molecular ions were observed at higher electron energies. Two mechanisms seem to be involved in the desorption process, namely, the Auger stimulated ion desorption and that of secondary electrons. These data may provide support to establish more accurate astrochemical models and contribute to explain the influence of solar wind on condensed alcohols.