Chemistry induced by low-energy electrons in condensed multilayers of pure small organic acids

Electron-induced decarboxylation in condensed films of formic acid HCOOH, partially deuterated acetic acid CH3COOD and trifluoroacetic acid CF3COOH, has been studied in the energy range 0.7–20 eV by high resolution electron energy loss spectroscopy (HREELS). The yield of carbon dioxide formation shows a peak around 1 eV irradiation energy associated with a resonant mechanism involving the transient negative ion [RCOOH]#− and an essentially non-resonant contribution increasing with irradiation energy above an onset located in the range 6–9 eV, depending on the carboxylic acid under consideration. The remarkable point of this study is that it is possible to selectively control the decarboxylation reaction by tuning the electron energy of irradiation.