title: Experimental characterization of singlet scattering channels in long-range Rydberg molecules.
abstract: We observe the formation of long-range Cs2 Rydberg molecules consisting of a Rydberg and a ground-state atom by photoassociation spectroscopy in an ultracold Cs gas near 6s1/2(F=3,4)→np3/2 resonances (n=26-34). The spectra reveal two types of molecular states recently predicted by D. A. Anderson, S. A. Miller, and G. Raithel [Phys. Rev. A 90, 062518 (2014)]: states bound purely by triplet s-wave scattering with binding energies ranging from 400 MHz at n=26 to 80 MHz at n=34, and states bound by mixed singlet-triplet s-wave scattering with smaller and F-dependent binding energies. The experimental observations are accounted for by an effective Hamiltonian including s-wave scattering pseudopotentials, the hyperfine interaction of the ground-state atom, and the spin-orbit interaction of the Rydberg atom. The analysis enables the characterization of the role of singlet scattering in the formation of long-range Rydberg molecules and the determination of an effective singlet s-wave scattering length for low-energy-electron-Cs collisions.
authors.affiliation: Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: Heiner
authors.initials: H
authors.lastname: Saßmannshausen
authors.affiliation: Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Merkt
authors.affiliation: Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
authors.forename: Johannes
authors.initials: J
authors.lastname: Deiglmayr