Theory of High-Energy Inelastic Collisions between Molecular Systems. Dissociation ofH2+on Collision withH2

Inelastic collisions between the hydrogen molecule ion (${\mathrm{H}}_2^{+}$) and the hydrogen molecule are investigated theoretically within the framework of the first Born approximation. The possibility that ${\mathrm{H}}_2^{+}$ may be in an excited vibrational state before the collision takes place is given special consideration. Appropriate sums of the theoretical cross sections are identified with the experimental measurements of the cross section ${\sigma }_1$, for the dissociation of ${\mathrm{H}}_2^{+}$ into a proton and hydrogen atom, and of ${\sigma }_1+{\sigma }_2$, where ${\sigma }_2$ is the ionization cross section of ${\mathrm{H}}_2^{+}$. Agreement is good between theory and ${\sigma }_1$ for collision energies greater than 50 keV and between theory and ${\sigma }_1+{\sigma }_2$ for collision energies greater than 1 MeV. Any discrepancies between experiment and theory can be identified as either the expected failure of the Born approximation at low energies or the omission of certain inelastic processes in the theoretical results.