Observation of a novel binding mechanism for ultra-long range molecules |
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| Vera Bendkowsky | |
| Universität Stuttgart | |
| Molecular bonds can be divided into four primary types: ionic, covalent, van der Waals and hydrogen bonds. At ultralow temperatures a novel binding type between a Rydberg atom and a ground state atom was predicted in 2000 [1]. The underlying mechanism for this new type of chemical bond is low-energy electron scattering of Rydberg electron from a polarizable ground state atom. This quantum scattering process can generate an attractive potential that is able to bind the ground state atom to the Rydberg atom at a well localized position within the Rydberg electron wave function. The resulting giant molecules can have an internuclear separation of several thousand Bohr radii, which places them among the largest known molecules to date. Ultracold and dense samples of atoms enable the creation of these molecules via Rydberg excitation. We present spectroscopic studies on these molecular states of Rubidium: the vibrational modes of the Rb(5S)-Rb(nS) dimers are investigated for principal quantum numbers n between 34 and 40. We observe clearly distinguishable bound states which binding energies are well represented by a Born–Oppenheimer model. Furthermore, the vibrational ground states of these molecules are characterized by lifetime and Stark effect measurements. [1] C. H. Greene, A. S. Dickinson, H. R. Sadeghpour, Phys. Rev. Lett. 85, 2458 (2000). |