Semiclassical treatment of high-lying electronic states of H
2+ and an approach for computing electronic spectra of long-range diatomic Rydberg molecules
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.
We show that the recently observed class of long-range ion-Rydberg molecules can be divided into two families of states, which are characterized by their unique electronic structures resulting from the ion-induced admixture of quantum defect-split Rydberg
nP states with different low-field-seeking high-
l states. We predict that in both cases, these diatomic molecular states can bind additional ground-state atoms lying within the orbit of the Rydberg electron, thereby forming charged ultralong-range Rydberg molecules (ULRMs) with binding energies similar to that of conventional nonpolar ULRMs. To demonstrate this, we consider a Rydberg atom interacting with a single ground-state atom and an ion. The additional atom breaks the system's cylindrical symmetry, which leads to mixing between states that would otherwise be decoupled. The electronic structure is obtained using exact diagonalization over a finite basis and the vibrational structure is determined using the multiconfiguration time-dependent Hartree method. Due to the lobelike structure of the electronic density, bound trimers with both linear and nonlinear geometrical configurations of the three nuclei are possible. The predicted trimer binding energies and excitation series are distinct enough from those of the ion-Rydberg dimer to be observed using current experimental techniques.
High-lying Rydberg atoms and molecules exhibit unusually long-range interactions, and the strongly enhanced interaction between Rydberg particles makes them unique for a variety of applications, ranging from quantum optics to chemistry [1]. Recent studies revealed that such high-lying Rydberg particles can be formed through electron trapping in strong field interaction with atoms and molecules [2, 3, 4]. In this submission, we report on imaging of high-lying Rydberg electron wave packets populated in such interactions.