Cross sections for electron capture and loss. I. ${\mathrm{H}}^{+}$ and ${\mathrm{H}}^{\mathrm{-}}$ impact on H and ${\mathrm{H}}_2$

The electron-capture cross sections for ${\mathrm{H}}^{+}$ impact on H and ${\mathrm{H}}_2$ and the electron-loss cross sections for ${\mathrm{H}}^{\mathrm{-}}$ impact on H and ${\mathrm{H}}_2$ have been measured for projectile energies between 2.0 and 0.063 keV. Relative cross-section values for all these reactions were measured directly, and placed on an absolute scale by adopting a standard value of 6.95×${10}^{\mathrm{-}16}$ ${\mathrm{cm}}^2$ for the electron-capture cross section for ${\mathrm{H}}^{+}$+${\mathrm{H}}_2$ collisions at 2.0-keV ${\mathrm{H}}^{+}$ energy. A crossed-beam technique was used, and the reaction-product H atoms were measured by a secondary-electron-emission detector. The techniques used to make the measurements are described, and the results are compared with other experimental and theoretical data.