Formation of Negative Ions in a Gas by Charge Transfer from a Fast Atomic Hydrogen Beam

Structure has been reported in the electron loss cross section for hydrogen atoms in ${\mathrm{H}}_2$. Study of various gases shows that there is no structure for collisions with argon, but nine peaks of magnitude ${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$ between 8 and 40 kev in CO. Analysis of these peaks support the idea advanced for hydrogen gas that the peaks are caused by formation of negative ions in the target gas by a process in which the electron is captured as though it were a free electron. Mass spectroscopic study reveals that negative ions are formed when hydrogen atoms pass through CO, ${\mathrm{O}}_2$, and ${\mathrm{H}}_2$O. The formation rate varies in CO as predicted from the ${\sigma }_{01}$ structure and the cross section is ∼${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$. The ions formed in CO are C${\mathrm{O}}^{-}$ and ${\mathrm{O}}^{-}$. The copious production of C${\mathrm{O}}^{-}$ contradicts the simple model of the capture collision previously proposed.