Cross sections for electron capture and loss. II. H impact on H andH2

The electron-capture and electron-loss reactions for H impact on H and ${\mathrm{H}}_2$ have been examined for projectile energies between 2.0 and about 0.1 keV. Relative cross sections for these reactions were measured directly, and the data for H targets were placed on an absolute scale by normalizing to the available results for ${\mathrm{H}}_2$ targets. For the electron-capture (ion-pair formation) reaction, some new data are also reported here for ${\mathrm{H}}_2$ targets. The crossed-beam techniques used to accomplish the measurements are described, and the results are compared with other experimental and theoretical data where possible.