Secondary Reactions in a Gas Discharge

The pressure variations of H⁺, H₂⁺, H₃⁺, He⁺, and HeH⁺ ions emanating from an electrodeless discharge in pure hydrogen and in mixtures of hydrogen and helium have been measured. Mass analysis was accomplished with a ``strong‐focusing'' mass spectrometer. The analysis of the results in hydrogen are discussed, as well as the alternative mechanisms for hydrogen dissociation. From the results in hydrogen‐helium mixtures, a value of 0.37±0.15 has been obtained for the ratio k₂′/k₁′; where k₂′ is the rate constant for reaction $${\mathrm{He}}^{+}+{\mathrm{H}}_2\to {\mathrm{HeH}}^{+}+\mathrm{H}$$ and k₁′ is the rate constant for the reaction $${\mathrm{H}}_2^{+}+{\mathrm{H}}_2\to {\mathrm{H}}_3^{+}+\mathrm{H}.$$ In addition, a value of 0.016±0.013 has been obtained for the ratio k₃′/k₂′, where k₃′ is the rate constant for the reaction $${\mathrm{H}}_2^{+}+\mathrm{He}\to {\mathrm{HeH}}^{+}+\mathrm{H}.$$