The Elastic Scattering and Neutralization of Low Velocity Hydrogen Ions in Methane

The low velocity scattering of ${\mathrm{H}}^{+},$ ${\mathrm{H}}_2^{+},$ and ${\mathrm{H}}_3^{+}$ in methane was measured at voltȧges between about 1 and 150. Neutralization is found in all three cases, being much greater for ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}^{+}$ than for ${\mathrm{H}}_3^{+}.$ The elastic scattering is also relatively high compared to hydrogen and helium. It was found that there was an effect of pressure at constant voltage on the experimental determination of effective cross section for elastic scattering. This has been explained on the basis of multiple scattering. Approximate potential laws for the interactions have been evaluated.