Diffusion and interaction potentials for K⁺ions in the noble gases

Abstract

The ratio DT/µ between the transverse diffusion coefficient and the mobility has been measured as a function of the electric field to density ratio E/N, for K+ ions in all the noble gases at a temperature of 295 K and with an accuracy of 1% or better. In helium, the experimental data are in excellent agreement with theoretical values obtained from a recent ab initio potential. In the other gases, the experimental data have been used to estimate interaction potential parameters, using a modified Tang-Toennies-type potential model with hyperpolarizabilities included and a generalized Born-Mayer-type repulsive term.

Spectroscopy of K+⋅Rg and transport coefficients of K+ in Rg (Rg=He–Rn)

“…25͒ also derived a model potential based upon a universal scaling procedure, again fitting to available mobility data. The two mobility-fitted potential energy curves 25,29 give good agreement with each other, with Ref. 25 obtaining R e ϭ2.97 Å and D e ϭ314 cm Ϫ1 , and Ref.…”

“…25 obtaining R e ϭ2.97 Å and D e ϭ314 cm Ϫ1 , and Ref. 29 obtaining corresponding values of 2.87 Å and 350 cm Ϫ1 . Again, in the present work, a wide range of R was used to calculate the potential for this species using both the aVQZ and aV5Z basis sets, and LEVEL employed to obtain spectroscopic constants.…”

“…28. The most accurate potential of these has been concluded 29 to be the modified version of the EGF potential. 28 We calculated potential energy curves over a wide range of R for the three sets of basis sets: aVQZ, aV5Z, and d-aV5Z.…”

“…Ahlrichs et al 23 derived a model potential for the system, and this was modified in the later work by Skullerud et al, 29 where two adjustable parameters were used to fit the potential to mobility data-this is denoted the SLT potential hereafter. In addition, KMV ͑Ref.…”

“…These values are in good agreement with the potential energy curves obtained from fits to mobility data. 25,29 Vibrational energy levels and rotational constants are given in Table IV for the lowest few levels.…”