Theory of Ultralong-Range Rydberg Molecule Formation Incorporating Spin-Dependent Relativistic Effects: Cs(6s)-Cs(np) as Case Study

Chemphyschem. 2016 Nov 18;17(22):3683-3691. doi: 10.1002/cphc.201600932. Epub 2016 Oct 31.

Abstract

We calculate vibrational spectra of ultralong-range Cs(32p) Rydberg molecules that form in an ultracold gas of Cs atoms. We account for the partial-wave scattering of the Rydberg electrons from the Cs perturber atoms by including the full set of spin-resolved 1,3 SJ and 1,3 PJ scattering phase shifts, and allow for the mixing of singlet (S=0) and triplet (S=1) spin states through Rydberg electron spin-orbit and ground state electron hyperfine interactions. Excellent agreement with observed data in Saßmannshausen et al. [Phys. Rev. Lett. 2015, 113, 133201] in line positions and profiles is obtained. We also determine the spin-dependent permanent electric dipole moments for these molecules. This is the first such calculation of ultralong-range Rydberg molecules for which all of the relativistic contributions are accounted.

Keywords: Rydberg systems; cold molecules; dipole moments; relativistic effects; vibrational spectroscopy.