Mobilities of various mass-identified positive and negative ions in helium and argon

Abstract

The mobilities of the ions CH3O2+, NO+⋅H2O, C2H2−, Cl−, O2−, O3−, NO2−, CO3−, SO3−, SO2F−, SF5−, and SF6− in helium and 0+, O2+, O3−, and CO3− in argon have been measured at room temperature with a flow–drift tube. The measurements were obtained over the range 5⩽E/N⩽120 Td for helium and 5⩽E/N ⩽270 Td for argon (1 Td=10−17 V⋅cm2). The E/N dependence of these data fits the general pattern observed previously for a variety of ions in helium and argon, with the exception that the O+ mobilities in argon exhibit a rare minimum. Several of the polyatomic ions, notably CH3O2+, NO+⋅H2O, and O3−, were observed to break up at elevated E/N.