Electron induced reactions in molecular nanofilms of chlorodifluoroacetic acid (CClF2COOH): Desorption of fragment anions and formation of CO2

Abstract

Electron induced reactions in molecular nanofilms of chlorodifluoroacetic acid (CClF(2)COOH) are studied by electron stimulated desorption (ESD) of fragment anions and temperature programed thermal desorption spectroscopy (TDS). The fragment anions O(-), F(-), OH(-), and Cl(-) are formed from broad resonance features in the energy range of 4-14 eV and assigned to dissociative electron attachment (DEA) of molecules or dimers at or near the surface of the film, followed by desorption. The strong low energy DEA resonances (0-2 eV) observed in a previous gas phase study [J. Kopyra et al., Int. J. Mass. Spectrom. 285, 131 (2009)] are completely suppressed in ESD. Electron irradiation at energies above 10 eV results in the formation of CO(2), as revealed by TDS. The extended irradiation of a 3 ML film (25 nA, 240 min) results in a nearly completely transformation of the initial compound in favor of CO(2) and other by-products.