Photoassociation spectra of cesium 31D<sub>5/2</sub>+6S<sub>1/2</sub>(<i>F</i> = 4) ultralong-range Rydberg molecules

Abstract

In this paper, we conduct the experiment and simulation on 31D<sub>5/2</sub>+6S<sub>1/2</sub>(<i>F</i> = 4) Cs<sub>2</sub> ultralong-range Rydberg molecules (ULRMs). These molecules are prepared by employing a two-photon photoassociation scheme. Two distinct ultralong-range Rydberg molecular signals are observed at the detuning –162.8 MHz and –66.6 MHz of 31D<sub>5/2</sub> atomic resonant line, which are bound by the pure triplet potential and mixed singlet-triplet potential, respectively. We use the model of scattering interaction between the Rydberg electron and ground-state atom to perform the simulation. The molecular potential-energy curves are obtained by solving the Hamiltonian on a grid of intermolecular distances <i>R</i>. The calculations of the binding energy of pure triplet and mixed singlet-triplet <i>v</i> = 0 vibrational states are compared with the experimental measurements. The calculated and measured values of the binding energy are in good agreement. The s-wave pure triplet and singlet zero-energy scattering length are obtained to be <inline-formula><tex-math id="M3">\begin{document}${a}_{{\rm{s}}}^{{\rm{T}}}({0})=-{19.16}{a}_{0}$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230520_M3.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230520_M3.png"/></alternatives></inline-formula> and <inline-formula><tex-math id="M4">\begin{document}$ {a}_{{\rm{s}}}^{{\rm{S}}}(0)=-{1.92}{a}_{0} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230520_M4.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="14-20230520_M4.png"/></alternatives></inline-formula>, respectively. This kind of molecule with large size, abundant vibrational states and large permanent electric dipole moment is an excellent candidate for studying low-energy collision dynamics. The study of these molecules will further deepen and enrich the understanding of the special binding mechanism and exotic properties of the ULRMs.