Mobilities of H3+ and HeH+ ions in helium gas and rate coefficient for HeH+ + H2 → H3+ + He

The mobilities of mass-identified H+3 and HeH+ ions in helium and the reaction rate coefficient for HeH+ + H2 → H+3 + He have been measured by a drift-tube quadrupole mass spectrometer at 300 K. The zero-field reduced mobilities of H+3 and HeH+ ions, corrected to 273 K, are 31.0+-0.8 and 23.4+-0.6 cm2V-1s-1 respectively. The reaction rate coefficient was found to be (1.26+-0.16) X 10-9 cm3s-1 and was observed to be independent of the mean ion kinetic energy in the range from 0.04 to 0.3 eV. (Auth.)