Electron-impact ionization cross section of formic acid

Mateusz Zawadzki

doi:10.1140/epjd/e2017-80540-8

Abstract

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 Å2 at 70 eV 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.Graphical abstract

Highlights

Collision of low energy electrons with organic molecules has been the subject of many studies over the last few decades
It is worth noting that recent theoretical first-principle molecular dynamics studies of Kohanoff and Artacho [3] predicted production of formic acid during radiolysis of water in low-energy carbon projectile bombardment
Formic acid (FA) plays an important role in the atmosphere, where it has an effect on precipitation chemistry and acidity [4]

Summary

Introduction

Collision of low energy electrons with organic molecules has been the subject of many studies over the last few decades. Apart of its presence in the Earth’s atmosphere, FA has been detected in the interstellar medium (ISM): in dark clouds [5], in the Galactic center (GC) [6], in the cometary coma of Hale-Bopp comet [7], in interstellar ices [8] and in chondritic meteorites [9]. All these discoveries have made the research of the interaction of FA with free electrons important from the point of view of atmospheric physics, astrophysics, astrobiology and post-irradiation chemistry [10]

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