The mobility of potassium ions in helium

The mobility of K+ ions in helium has been measured at 76.8 K and E/N values up to 15 Td. and at room temperature up to 300 Td. The experimental scatter is of the order of 0.1-0.2%. The experimental mobilities are compared with values calculated from a new and accurate ab initio potential (Roeggen et al 1996). The agreement between experimental and theoretical values is significantly better than in earlier studies of this ion-atom system, but some unexplained discrepancies of the order of 1% still exist. (Author)