Transport property predictions for laser resonance chromatography on Rf⁺ (Z = 104)

We propose a theoretically designed laser resonance chromatography (LRC) experiment on Rf⁺ (Z = 104) drifting in He buffer gas. To this end, we first developed a four-level rate equation model that simulates the optical pumping of Rf⁺ from its ground state, ²D3/2 (7s²6d¹), to the metastable ⁴F3/2 (7s¹6d²) state via laser resonant excitation of the intermediate ⁴F3/2 (7s¹6d¹7p¹) state prior to electronic state chromatography. This model predicts a 93% pumping efficiency that suffices to enable efficient laser resonance chromatography of this ion. We then performed accurate relativistic Multi-Reference Configuration-Interaction (MRCI) calculations to model the interaction of Rf⁺ with He in the ground ²D3/2 (7s²6d¹), low-lying ²D5/2 (7s²6d¹), and metastable ⁴F3/2 (7s¹6d²) states. These ion-atom interaction potentials were used to calculate the state-specific ion mobilities. For gas temperatures above 100 K and small applied electric fields, the reduced ion mobilities of the ground and metastable states differ significantly. In particular, at room temperature the difference between the reduced ion mobilities of these states is larger than 11%, and therefore should be sufficiently large to ensure LRC of this ion.