Drift and longitudinal diffusion of lithium ions in helium

The drift velocity and the longitudinal diffusion coefficient have been measured for Li + ions in He and 296 K and for 7<or=E/n 0 <or=180 Td, using a Tyndall-Powell type double-shutter drift tube with variable length. Above 40 Dt, the results disagree with previously published data. The disagreement can be traced to an inadequate analysis of the experimental arrival time spectra in the earlier works. The present data are however in good agreement with predictions based on ab initio interaction potentials, at high values of E/n 0 .