Experimental measurement of H3+/H5+ and D3+/D5+ mobilities in their parent gases

The experimental study of the reduced mobility K₀ of the molecular ions H₃⁺/H₅⁺ in H₂ and D₃⁺/D₅⁺ in D₂ was carried out using a recently developed technique, that uses a Xe VUV flash lamp and a Gaseous Electron Multiplier (GEM) microstructure with a CsI deposit to produce the molecular ions by electron avalanche ionization. For both gases, the K₀ values were obtained at room temperature (295 K) and at pressures from 5 to 50 Torr for uniform reduced electric fields E/N from 4 to 40 Td. The reduced mobility derived from the measurements is an average of the K₀ value of the two molecular ions, and for the H₃⁺ and H₅⁺ ions is 11.1 cm²V^-1s^-1 while for D₃⁺ and D₅⁺ it ranges from 8.5 to 7.8 cm²V^-1s^-1, for pressure from 5 to 50 Torr. A discussion of the obtained results is presented.