Formation of H3+ and H5+ Ions

H+, H2+, H3+, and H5+ ions have been identified in hydrogen gas by use of a mass spectrometer with the ion source in the pressure range from 10−3 to 0.5 mm Hg. Secondary ions are formed in steps of consecutive reactions between ions and hydrogen molecules. Reaction cross sections of the secondary H3+ ions have been determined from the concentration dependence of the intensities of the H2+ ions. The tertiary H5+ ion is formed in three-body collisions of the H3+ ion with the hydrogen molecules. Dissociation processes of all three molecular ions have been observed.