Small Exotic Molecules with Bosonic Constituents

一博 崎本, Kazuhiro Sakimoto

Weibin Li, Thomas Pohl, Jan Michael Rost +8 more

Permanent electric dipole moments in molecules require a breaking of parity symmetry. Conventionally, this symmetry breaking relies on the presence of heteronuclear constituents. We report the observation of a permanent electric dipole moment in a homonuclear molecule in which the binding is based on asymmetric electronic excitation between the atoms. These exotic molecules consist of a ground-state rubidium (Rb) atom bound inside a second Rb atom electronically excited to a high-lying Rydberg state. Detailed calculations predict appreciable dipole moments on the order of 1 Debye, in excellent agreement with the observations.

Collective

Chris H. Greene

This talk will present several exciting nuggets from the last half-century of progress in our understanding of Rydberg electron physics in atoms and small molecules. Some key elements of this deepened understanding have emerged from experiments that were understood through the multichannel quantum defect theory developed by Seaton, Fano, Jungen and their collaborators. That powerful combination has enabled spectra of remarkable complexity and richness to be quantitatively understood and qualitatively interpreted using this framework. Another aspect of Rydberg physics connects with Enrico Fermi’s treatment of the interaction between a slow electron and a distant ground state atom, which has been predicted to generate a new chemical bonding mechanism that can bind an exotic long range diatomic or triatomic molecule whose internuclear distances can be as large as a small virus. The production of this class of exotic, weakly-bound Rydberg molecules has been demonstrated in a remarkable series of experiments in the last few years.

Gerhard Backenstoss

Bout Marcelis, Dmitry S. Petrov, S. J. J. M. F. Kokkelmans +1 more

We consider weakly bound bosonic and fermionic heteronuclear molecules (dimers) in ultracold atomic gases, where the interspecies interaction is characterized by a large positive scattering length. We develop a new theoretical approach to solve the four-body scattering problem, which is valid when the mass ratio between the constituent atoms is sufficiently large. This approach is then used to study elastic and inelastic dimer- dimer scattering processes in the case that the light constituent atoms are fermions, while the heavy atoms can be either fermions or bosons. Due to the Fermi statistics of the light atoms, the heavy atoms experience a strong repulsion at large intermolecular distances. This leads to suppression of the collisional relaxation to universal trimer (Efimov) states and/or deeply bound molecular states. We present the formation rate of Efimov trimers as a function of the three-body parameter for several experimentally interesting systems. The competition between the formation of trimers and relaxation to deeply bound molecules is analyzed, and prospects for future studies of these systems are discussed.