Ab initio HeF+(3∑, 3Π) interaction potentials and calculations of the mobility of F+(3P) and F–(1S) in helium

Abstract

The mobility of F⁺(³P) in helium has been calculated using both the two-temperature and three-temperature theories of ion transport. The interaction potentials for the two possible molecular states HeF⁺(³∑) and HeF⁺(³Π) required by the transport theories were calculated at the MP4SDQ/6–311 + G(3df, 3dp) level of theory. The mobility of F⁺ in helium derived by summing over the appropriate statistical weights for the two molecular ion states separating to He(¹S)+ F⁺(³P) is in good agreement with experimental data. The mobility of the F^–(¹S) ion in helium has been calculated at the three-temperature level of theory using an interaction potential calculated at the MP4SDQ/6–311 + G (3df, 3dp) level of theory and refined by fitting to low-field experimental mobility measurements. The mobilities calculated with this potential were found to be in good accored with the values calculated using an HeF^–(¹∑) MBPT(4) interaction potential incorporating a very large basis set.