Date of Original Version
We have measured the mobility of positive ions in 4He vapor for temperatures between 1.3 and 2.0 K and for saturation ratios between 0.1 and 1.0. We present a model which relates the size of a charged droplet to its mobility and find good quantitative agreement with our data when we calculate the size of the droplet which forms about the ion with classical macroscopic thermodynamic arguments. The radius thus obtained ranges from 7 to 9 Å.
\Akinci, G., & Northby, J. A. (1978). Charged Droplets in Cryogenic 4He Vapor. Physical Review Letters, 42(9), 573-576. doi: 10.1103/PhysRevLett.42.573
Available at: http://dx.doi.org/10.1103/PhysRevLett.42.573