Absolute cross sections have been determined for the production of hydrogen atoms in the $3s$ state by the dissociation of fast (20-120 keV) ${\mathrm{H}}_2^{+}$ and ${\mathrm{H}}_3^{+}$ projectiles on impact with ${\mathrm{H}}_2$, He, Ar, and Ne. A cross section has also been determined for 100-keV ${\mathrm{H}}_2^{+}$ impact on ${\mathrm{N}}_2$. For 100-keV ${\mathrm{H}}_2^{+}$ impact on these gases, the production of atoms in the $3s$ state represents about 3% of the reaction ${\mathrm{H}}_2^{+}$→${\mathrm{H}}^{+}$ + H.

• Received 21 September 1967

DOI:https://doi.org/10.1103/PhysRev.167.26