AbsoluteH−detachment cross sections

Absolute detachment cross sections for 200-eV to 10-keV ${\mathrm{H}}^{-}$ on He, Ar, ${\mathrm{H}}_2$, ${\mathrm{N}}_2$, and ${\mathrm{O}}_2$ were measured to an accuracy of 7% using the beam-attenuation method. The cross sections, approximately (5-25) × ${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$, all increase slowly with increasing collision energy, except for ${\mathrm{O}}_2$, in which case the cross section decreases with increasing impact energies up to 4 keV. The present results are compared with previous measurements. A semiempirical theory based on low-energy-electron scattering predicts the detachment cross sections with some success.