Triple ionization of Ne¹⁺ forming Ne⁴⁺. The filled circles show the data of Tinschert (1989) and the filled squares indicate other unpublished data from the group of E. Salzborn (2016, private communication). The dashed curve uses Equation (1), but the peak is clearly broader than the measurement. Instead, we fit the data using Equation (2). Although developed for double-ionization cross sections, it fits these triple-ionization data well.