Accurate gaseous ion mobility measurements

It is shown that theoretical values of the mobility of atomic ions in gases can be used to calibrate a drift-tube mass spectrometer, leading to subsequent measurements that are accurate to 0.6% for He⁺ in He near room temperature as the ratio of the electrostatic field strength to the gas number density ranges up to 2 × 10⁻¹⁹ Vm². Values of the ratio of the parallel diffusion coefficient to the mobility are also obtained.