Abstract
We have performed high-resolution two-photon dark-state spectroscopy of an ultracold gas of molecules in the state at a magnetic field of about 1000 G. The vibrational ladder as well as the hyperfine and low-lying rotational structure are mapped out. Energy shifts in the spectrum are observed due to singlet-triplet mixing at binding energies as deep as a few hundred . This information, together with data from other sources, is used to optimize the potentials of the and states in a coupled-channel model. We find that the hyperfine structure depends weakly on the vibrational level. This provides a possible explanation for inaccuracies in recent Feshbach resonance calculations.
2 More- Received 10 September 2010
DOI:https://doi.org/10.1103/PhysRevA.82.052514
©2010 American Physical Society