The Dissociation of ${\mathrm{C}}_2$${\mathrm{H}}_2$${\mathrm{D}}_2$ by Electron Impact

The dissociation of ${\mathrm{C}}_2$ ${\mathrm{H}}_2$ ${\mathrm{D}}_2$ by electron impact has been investigated. In order to obtain a consistent interpretation of the distribution of intensities of the different ions produced, it is necessary to assume that there is a selective process favoring the splitting of the C - H bond over the splitting of C - D. The probability $p$ introduced to take this effect into account has been calculated. From that value of $p$, an estimate of the intensity of the ion ${\mathrm{C}}_2$HD has been made, which agrees with the measured one. In addition to that, it has been shown that the formation of C${\mathrm{H}}_2$ in ${\mathrm{C}}_2$ ${\mathrm{H}}_4$ is a splitting of the double bond between the carbons alone, and that in the formation of ${\mathrm{H}}_2^{+}$ in ${\mathrm{C}}_2$ ${\mathrm{H}}_4$, the hydrogen atoms come from the same radical.