Ion?Molecule Reactions and Mobilities of SF3+ and SF5+ Ions in SF6 Gas

Abstract

Positive ion-molecule reactions in 8F6 were studied in a static drift-tube mass spectrometer using electron impact at 100 eY as the ion source. The ratio of electric field strength to gas number density, E / N, was typically varied from 40-282 Td and pressure ranged from 0·1 to o· 8 Torr. The most important processes were found to be 8Ft + SF6 ---+ 8Ft + 8F6 + F2 and 8Ft + 8F6 ---+ (82Fg)+* ---+ 82Ft + F 2. The interaction potentials for the 8Ft and 8Ft ions in SF6 were also found by using the measured mobility data which were obtained using a pulsed-ion transit-time method. We found that the (12,4, a* = 0·1) core model was adequate to describe the mobility over the range of E / N studied. The zero-field reduced mobilities for 8Ft and 8Ft were determined to be 0·68 and 0·55cm2y-1 s- 1 respectively.