Energy Dependence of Cross Sections for Ion—Molecule Reactions. Transfer of Hydrogen Atoms and Hydrogen Ions

This report describes measurements of cross sections for ion—molecule reactions by use of a technique which involves preselection of the primary ion in terms of both mass and kinetic energy. Cross sections as functions of ion kinetic energy are given for the reactions $$\begin{array}{cc}{\mathrm{Ar}}^{+}+{\mathrm{D}}_2\to {\mathrm{ArD}}^{+}+\mathrm{D},& {\mathrm{N}}_2^{+}+{\mathrm{D}}_2\to {\mathrm{N}}_2{\mathrm{D}}^{+}+\mathrm{D},\\ {\mathrm{H}}_2^{+}+{\mathrm{H}}_2\to {\mathrm{H}}_3^{+}+\mathrm{H},& {\mathrm{D}}_2^{+}+{\mathrm{N}}_2\to {\mathrm{N}}_2{\mathrm{D}}^{+}+\mathrm{D},\\ {\mathrm{H}}_2^{+}+\mathrm{He}\to {\mathrm{HeH}}^{+}+\mathrm{H},& {\mathrm{D}}_2^{+}+\mathrm{Ar}\to {\mathrm{ArD}}^{+}+\mathrm{D}.\end{array}$$ The behavior of the cross sections for the first two of these reactions, which can be considered to involve hydrogen atom transfer, is strikingly different from that of the remaining four, which can be taken as cases of hydrogen ion transfer. The comparison with previous measurements shows fair agreement; however, agreement with existing theories is rather poor.