Partial-ionization cross sections of aCO2molecule due to impact of 10–26-keV electrons

Abstract

Experimental data on total- and partial-ionization cross sections of ionic fragments of ${\mathrm{CO}}_{2}$ molecule produced by impact of 10--26-keV electrons are obtained on a crossed-beam apparatus in our laboratory. An ejected electron-produced ion-coincidence technique is employed together with a time-of-flight mass spectrometer for analysis of the ions. The six ionic fragments, ${\mathrm{CO}}_{2}{}^{+}$, ${\mathrm{CO}}^{+}$, ${\mathrm{CO}}_{2}{}^{2+}$, ${\mathrm{O}}^{+}$, ${\mathrm{C}}^{+}$, and ${\mathrm{C}}^{2+}$, resulting from dissociative ionization of the ${\mathrm{CO}}_{2}$ molecule are observed and identified; their relative ionization cross sections and branching ratios are determined as a function of impact energy. The binary-encounter Bethe model is found to overestimate the experimental data for total-ionization cross sections of the observed ions. No other experimental or theoretical data exist in the investigated energy range to make a direct comparison with the present results.