Electron-Induced Reactions in Condensed Acetaldehyde: Identification of Products and Energy-Dependent Cross Sections

Thermal desorption spectrometry (TDS) is used to measure cross sections for reactions induced in condensed thin films of acetaldehyde by low-energy electrons with incident energies ranging from 4 to 15 eV. The obtained values for the decay of acetaldehyde and the formation of CO and CH4 are in reasonable agreement with cross sections obtained previously for similar samples by high-resolution electron energy loss spectroscopy (HREELS). In addition to propionaldehyde that has been identified as additional product previously, evidence of the formation of 2-propanol, ethanol, CO2, and ethylene is obtained here. Whereas the former two may result directly from an attack of methyl and H radicals released upon electron-induced fragmentation of acetaldehyde on an adjacent molecule, CO, is shown to be formed through electron-induced reactions of the initial product CO. The production of ethylene can be explained by rapid elimination of H2O from ethanol under electron exposure.