Heteronuclear long-range Rydberg molecules

In this contribution, I will present recent spectroscopic results of the photoassociation of heteronuclear long-range Rydberg molecules (LRMs) in a dual-species MOT of ³⁹K and ¹³³Cs atoms [1]. This represents the first experimental study on heteronuclear bialkali LRMs. LRMs are bound states of a Rydberg atom and a ground-state atom located within the orbit of the Rydberg electron, with the binding originating from the Rydberg electron–ground-state atom scattering interaction [2]. We study the density dependence of the photoassociation rates which sensitively depend on the relative pair-correlation functions of the two elements [3]. By selectively exchanging the Rydberg and perturber atom, we systematically vary the binding interactions. High-resolution photoassociation and millimeter-wave spectra are modelled by ab-initio theoretic models. This work paves the way to obtain low-energy electron-atom scattering phase shifts from improved theoretical models of the experimentally observed binding energies, and the formation of plasmas consisting of oppositely charged particles with equal mass [4]. [1] M. Peper, and J. Deiglmayr, Phys. Rev. Lett. 126, 013001 (2021). [2] C. H. Greene, A. S. Dickinson, and H. R. Sadeghpour, Phys. Rev. Lett. 85, 2458 (2000). [3] J. D. Whalen et al., Phys. Rev. A 101, 060701(R) (2020). [4] M. Peper, and J. Deiglmayr, J. Phys. B 53, 064001 (2020).