Abstract
We present precision measurements with MHz uncertainty of the energy gap between asymptotic and well bound levels in the electronic ground state of the molecule. The molecules are prepared in a highly collimated particle beam and are interrogated in a -type excitation scheme of optical transitions to long range levels close to the asymptote of the ground state, using the electronically excited state as the intermediate one. The transition frequencies are measured either by comparison with lines or by absolute measurements using a fs-frequency comb. The determined level energies were used together with Feshbach resonances from cold collisions of and reported from other authors to fit ground state potentials. Precise scattering lengths are determined and tests of the validity of the Born-Oppenheimer approximation for the description of cold collisions at this level of precision are performed.
- Received 16 April 2008
DOI:https://doi.org/10.1103/PhysRevA.78.012503
©2008 American Physical Society
Synopsis
Potassium atoms feel a distant attraction
Published 28 July 2008
The atoms in highly excited vibrational states of a diatomic molecule can be quite far apart near their maximum excursion. Physicists are now using laser spectroscopy to carefully measure the long-range effective interaction between potassium atoms in these states—an essential parameter to understanding ultracold atomic collisions.
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