Electron-impact ionization cross section of formic acid
Experimental electron-impact ionization cross sections of one of the simplest carboxylic acids, formic acid, are presented. The molecular target was studied in two independent experimental setups applying different methods: the total ion collection and the electron–impact mass spectrometry methods. Experimental data were taken at incident electron energies ranging from ionization threshold [11.31 eV; J.C. Traeger, Int. J. Mass Spectrom. Ion Process. 66, 271 (1985)] to 76 eV using a total cross section of 4.0 ̊A2 at 70eV for the total ion collection method. In the spectrometric method the four main cations COH+, HCOOH+, COOH+ and CO+ are found to contribute to about 97% of the total ionization cross section.
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