Thermal desorption spectrometry for identification of products formed by electron-induced reactions

Thermal desorption spectra of thin films of acetaldehyde and hexamethyldisiloxane were recorded before and after exposure to electrons with an energy of 15 eV to monitor the formation of the products CO, propionaldehyde, and methane. While the identification of the products in previous work reported in literature has relied on a comparison with desorption temperatures of pure multilayer films, it is proposed here to compare with reference samples containing specific amounts of the anticipated product. It is shown that this approach is more accurate because the desorption temperatures can be modified considerably by a molecular matrix or by coadsorbates. Also trapping of the products within a molecular film can occur and lead to a delayed desorption as exemplified by the production of methane in thin films of hexamethyldisiloxane.