Reactions between H+ and D2

Abstract

Cross sections have been measured for the production of D₂⁺, HD⁺, and D⁺ in reactions between H⁺ and D₂. The initial kinetic energies $E_{\mathrm{c.m.}}$ in the center‐of‐mass system are between 0.3 and 80 eV. The total cross section ${\sigma }_T$ for these reactions can be represented by ${\sigma }_T{\text{\hspace{0.17em}=\hspace{0.17em}1.54 E}}_{\mathrm{c.m.}}^{\text{−0.7}}$ for ${\text{8\hspace{0.17em}≤\hspace{0.17em}E}}_{\mathrm{c.m.}}\text{\hspace{0.17em}≤\hspace{0.17em}80}\mathrm{eV}$ , and ${\sigma }_T{\text{\hspace{0.17em}=\hspace{0.17em}2.11 E}}_{\mathrm{c.m.}}^{\text{−1.43}}$ for ${\text{0.3\hspace{0.17em}≤\hspace{0.17em}E}}_{\mathrm{c.m.}}\text{\hspace{0.17em}≤\hspace{0.17em}2}\mathrm{eV}$ , where ${\sigma }_T$ is in square angstroms, and $E_{\mathrm{c.m.}}$ is in electron volts. Apparent thresholds for the endothermic reactions $${\mathrm{H}}^{+}+{\mathrm{D}}_2\to {\mathrm{D}}_2^{+}+\mathrm{H},$$ $${\mathrm{H}}^{+}+{\mathrm{D}}_2\to {\mathrm{HD}}^{+}+\mathrm{D}$$ are found at $E_{\mathrm{c.m.}}\text{\hspace{0.17em}=\hspace{0.17em}1.84\hspace{0.17em}±\hspace{0.17em}0.3}\mathrm{eV}$ . The cross section for $${\mathrm{H}}^{+}+{\mathrm{D}}_2\to {\mathrm{D}}^{+}+\mathrm{HD}$$ drops rapidly with increasing energy. For $E_{\mathrm{c.m.}}\text{\hspace{0.17em}≳\hspace{0.17em}6}\mathrm{eV}$ , D⁺ appears to be produced mostly by the reaction H⁺+D₂→D⁺+D+H. When $E_{\mathrm{c.m.}}\text{\hspace{0.17em}≳\hspace{0.17em}8}\mathrm{eV}$ , the reaction products are primarily $D_2^{+}$ and a smaller amount of D⁺. There is only fair agreement between these results and those of previous studies.