dc.creator Pechkis, H. K. en_US dc.creator Wang, D. en_US dc.creator Huang, Y. en_US dc.creator Eyler, E. E. en_US dc.creator Gould, P. L. en_US dc.creator Stwalley, W. C. en_US dc.creator Koch, C. P. en_US dc.date.accessioned 2008-01-12T14:00:19Z dc.date.available 2008-01-12T14:00:19Z dc.date.issued 2007 en_US dc.identifier 2007-RJ-04 en_US dc.identifier.uri http://hdl.handle.net/1811/31494 dc.description Author Institution: Physics Department, University of Connecticut, Storrs, CT 06269; Institut fur Theoretische Physik, Freie Universitat Berlin, 14195 Berlin, Germany en_US dc.description.abstract We describe experimental and theoretical studies of the effects of resonant electronic state coupling on the formation of ultracold ground-state $^{85}$Rb$_2$. The molecules are formed by photoassociation of ultracold atoms in a MOT into the 0$_u^+$ state converging to the $5S+5P_{1/2}$ limit, followed by radiative decay into high vibrational levels of the ground electronic state, $X\ ^1\Sigma_g^+$. The populations of these high-$v$ ground-state levels are monitored by resonance-enhanced two-photon ionization (R2PI) through the $2\ ^1\Sigma_u^+$ state. We find that the populations of vibrational levels $v''$=112-116 are far larger than can be accounted for by the Franck-Condon factors for $0_u^+ \leftarrow X\ ^1\Sigma_g^+$ transitions. Further, the total number of ground-state molecules formed by this process exhibits oscillatory behavior as the PA laser is tuned through a succession of $0_u^+$ state vibrational levels. Both of these effects are explained by a new calculation of transition amplitudes that includes the resonant character of the spin-orbit coupling between the two $0_u^+$ states converging to the $5P_{1/2}$ and $5P_{3/2}$ limits. The resulting enhancement of more deeply bound ground-state molecule formation will be useful for future experiments on ultracold molecules. \vspace{12 pt} We also describe evidence from our R2PI spectra for extensive singlet-triplet mixing between excited states of Rb$_2$ at intermediate internuclear separations, apparently also induced by spin-orbit interactions. In particular, the $3\ ^1\Sigma_g^+$ and $1\ ^1\Delta_g$ states converging to $5s+4d$ have been observed in excitation from the $a\ ^3\Sigma_u^+$ state,}, 261 (2006).} and the $2\ ^3\Pi_u$ state has been observed in excitation from the $X\ ^1\Sigma_g^+$ state. en_US dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title RESONANCE-ENHANCED PHOTOASSOCIATIVE FORMATION OF GROUND-STATE Rb$_2$ AND SPECTROSCOPY OF MIXED-CHARACTER EXCITED STATES en_US dc.type article en_US
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