Unusual kinetics of ions in a discharge plasma: ambipolar diffusion and mobilities of ArD+ in argon, helium and neon

Infrared diode laser kinetic spectroscopy has been employed for measurement of the decay of ArD+ ions. The lifetime of ArD+ increases with increasing buffer gas pressure from 20 to 100 μs in a cylindrical (radius 7.5 and 10.5 mm) glow discharge plasma and, from 200 to 600 μs in a hollow cathode (radius 20 mm) discharge plasma. The changes in ArD+ lifetime range from 7.9 to 92 μs/torr and depend on the type of buffer gas (Ne, He, Ar) and cell radius. The unusual kinetics of ArD+ is controlled by ambipolar diffusion and by the ion mobilities.