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We use photoassociation (PA) of ultracold atoms to produce ultracold KRb molecules in high vibrational levels of the lowest-lying singlet (X) and triplet (a) states[1,2]. The heteronuclear PA takes place in overlapping "dark-spot" MOTs of 39K and 85Rb. Ultracold molecules which have radiatively decayed to these lower states are detected by two-photon one-color pulsed ionization[3]. The ionization detection takes advantage of one-photon resonances to specific upper states at wavelengths near 600 nm. Scanning the detection laser allows us to map out the vibrational structures of both the lower and upper states. Such state-selective detection spectra also yield the ground-state vibrational distributions. We find that the molecules reside predominantly in high-lying levels, bound by less than 30 wavenumbers. We have also used a cw laser to perform rotationally-resolved "depletion" spectroscopy of the ultracold KRb molecules. As this depletion laser is scanned, dips are observed in the ionization signal when a transition to a specific rovibrational level of an upper state is driven. We plan to use such a transition as the first step of a Raman transfer process from high-v to v=0, in order to produce truly polar molecules. *Research supported by the NSF and carried out in collaboration with D. Wang, C. Ashbaugh, E.E. Eyler, and W.C. Stwalley. [1] D. Wang, J. Qi, M.F. Stone, O. Nikolayeva, H. Wang, B. Hattaway, S.D. Gensemer, P.L. Gould, E.E. Eyler, and W.C. Stwalley, Phys. Rev. Lett. 93, 243005 (2004). [2] D. Wang, J. Qi, M.F. Stone, O. Nikolayeva, B. Hattaway, S.D. Gensemer, H. Wang, W.T. Zemke, P.L. Gould, E.E. Eyler, and W.C. Stwalley, Eur. Phys. J. D 31, 165 (2004). [3] D. Wang, E.E. Eyler, P.L. Gould, and W.C. Stwalley, Phys. Rev. A 72, 032502 (2005). |
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