Mobility and longitudinal diffusion of SF₃⁺and SF₅⁺in SF₆

The reduced mobility and longitudinal diffusion coefficients of SF 3 + and SF 5 + in SF 6 have been measured with a drift tube mass spectrometer over the ranges 30-360 Td and 20-510 Td, respectively. The extrapolated zero-field reduced mobilities were found to be 0.651+or-0.009 cm 2 V -1 s -1 for SF 3 + and 0.591+or-0.006 cm 2 V -1 s -1 for SF 5 + . A comparison of the present mobility data for SF 5 + with previous work carried out without mass analysis strongly suggest that the unidentified ions were SF 5 + . No other data over the present range of measurement were found to be available for comparison.