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.