Bulletin of the American Physical Society
2006 37th Meeting of the Division of Atomic, Molecular and Optical Physics
Tuesday–Saturday, May 16–20, 2006; Knoxville, TN
Session L5: Photoassociation Spectroscopy |
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Chair: Thomas Killian, Rice University Room: Knoxville Convention Center 301AB |
Thursday, May 18, 2006 10:30AM - 10:42AM |
L5.00001: Saturation Effects in Photoassociation Spectroscopy of $^{86}$Sr P.G. Mickelson, Y.N. Martinez, S.B. Nagel, T.C. Killian This work describes intensity saturation of photoassociative transitions of $^{86}$Sr at the quantum mechanical unitarity limit. The saturation behavior, which results in a roll-over of the photoassociation rate for intensities greater than the saturation intensity, is reminiscent of Landau-Zener physics. Unlike other photoassociation spectroscopy (PAS) experiments, photoassociation occurs in a magneto-optical trap operating on the narrow dipole-forbidden transition at 689 nm. A laser red-detuned from the principal atomic transition at 461 nm by as much as 1300 GHz induces the photoassociation of ground state atoms to excited molecular states. Our previous studies suggest that some of the PAS transitions for $^{86}$Sr are sensitive to the intensity of the exciting laser; this work delves more deeply into these high intensity effects. [Preview Abstract] |
Thursday, May 18, 2006 10:42AM - 10:54AM |
L5.00002: Photoassociation of $^{85}$Rb Atoms in $0_{u}^{+}$ States Near the 5S+5P Atomic Limits T.H. Bergeman, Ye Huang, Hyewon K. Pechkis, Jianbing Qi, Dajun Wang, P.L. Gould, E.E. Eyler, W.C. Stwalley, R.A. Cline, J.D. Miller, D.J. Heinzen Analysis of photoassociation data on $^{85}$Rb atoms in a MOT (U. Conn.) or FORT (U. Texas) into $0_{u}^{+}$ states below the 5S+5P$_{1/2}$ (U. Conn.) and 5P$_{3/2}$ (U. Texas) limits reveals perturbations between the manifolds of states dissoociating to these two limits. These perturbation effects are exchibited most clearly as peaks in values of $B(v)$ vs. $v$ below the 5P$_{1/2}$ limit where intermixings with levels associated with the 5P$_{3/2}$ limit are maximal. From precision experimental data, we have fit long range and medium long range potentials and R-dependent spin-orbit functions. We will comment on deviations of observed energies from well known near-dissociation-limit expansion formulae. [Preview Abstract] |
Thursday, May 18, 2006 10:54AM - 11:06AM |
L5.00003: High intensity photoassociation spectroscopy of ultracold strontium atoms: nonperturbative theoretical analysis Philippe Pellegrini, Robin C\^ot\'e, Tom Killian High precision spectroscopy of excited molecular states at very large internuclear distance can be realized by a photoassociation process in which two colliding ultracold atoms in their ground state absorb a photon from a laser field in resonance with an excited ro-vibrational bound molecular level. The theoretical analysis of experimental spectra is usually based on a perturbative approach only valid in the low intensity regime. Due to very favorable transition dipole moments in strontium, the saturated regime occurs with laser intensities which can be easily reached experimentally. We will present a nonpertubative analysis of photoassociation spectra at high intensities. New features in the photoassociation lineshapes will be presented and the role of the last bound level of the ground molecular potential will be discussed. [Preview Abstract] |
Thursday, May 18, 2006 11:06AM - 11:18AM |
L5.00004: Theory of Alkaline-Earth Photoassociation in a 2D Geometry Pascal Naidon, Paul Julienne, Roman Ciurylo, Tanya Zelevinsky, Martin M. Boyd, Andrew D. Ludlow, Tetsuya Ido, Jun Ye The narrow intercombination line in alkaline-earth species allows weak photoassociation transitions which present novel features with respect to usual photoassociation in cold alkali species. In particular, we show that the line shape is sensitive to the dimensionality of the system. We applied this theory to the JILA photoassociation experiment on 88Sr performed in a 1D optical lattice at the magical wave length. A simple model reproduces the observed molecular energy levels. The model also allows us to predict the 2D thermal line shapes observed in the experiment and calculate the strength of optical Feshbach resonances for this system. [Preview Abstract] |
Thursday, May 18, 2006 11:18AM - 11:30AM |
L5.00005: Narrow Line Photoassociation in an Optical Lattice Tanya Zelevinsky, Martin M. Boyd, Andrew D. Ludlow, Tetsuya Ido, Jun Ye, Roman Ciurylo, Pascal Naidon, Paul S. Julienne Photoassociation spectroscopy was performed on the $^1$S$_0-^3 $P$_1$ intercombination line of $^{88}$Sr in a magic wavelength optical lattice. The long lifetime of $^3$P$_1$ permitted the study of nine least-bound states associated with the $0_u$ and $1_u$ molecular potentials. We investigated the crossover region between dipole-dipole and van der Waals interactions, and constrained the $C_3$ and $C_6$ coefficients. We also showed that the least-bound state should enable extensive, low- loss optical tuning of the very small ground state scattering length. Narrow line photoassociation in the lattice allowed us to observe thermal line shapes even at microkelvin temperatures, as well as to explore dimensional effects. [Preview Abstract] |
Thursday, May 18, 2006 11:30AM - 11:42AM |
L5.00006: State-selective detection by two-photon ionization and magnetic trapping of ultracold Rb$_{2}$ triplet state molecules Hyewon K. Pechkis, Ye Huang, Dajun Wang, E.E. Eyler, P.L. Gould, W.C. Stwalley We have produced and detected ultracold $^{85}$Rb$_{2}$ in high vibrational levels of the lowest triplet state, $a{ }^3\Sigma { }_u^+ $, by one-color resonance-enhanced two-photon ionization through the $2{ }^3\Sigma _g^+ $state, in the transition energy range of 14000-17000 cm$^{-1}$. The cold molecules are formed by photoassociation followed by radiative decay into the $a{ }^3\Sigma { }_u^+ $state. Many levels corresponding to the$2{ }^3\Sigma _g^+ $,$2{ }^3\Pi { }_g^ $,$1{ }^3\Delta _g $, and $3{ }^1\Sigma { }_g^+ $ states have been observed for the first time, and the vibrational levels of the $a{ }^3\Sigma { }_u^+ $state have been assigned. Experimental spectroscopy agrees well with a new theoretical analysis. In particular, the measured vibrational spacings correspond very well with those calculated from the potential curves of the $a{ }^3\Sigma { }_u^+ $state and the $2{ }^3\Sigma _g^+ $state. The relative vibrational state populations are also consistent with the Franck-Condon factors. Additionally, we present evidence for the trapping of triplet $^{85}$Rb$_{2}$ molecules by the inhomogeneous magnetic field of our MOT. This work is supported by NSF. [Preview Abstract] |
Thursday, May 18, 2006 11:42AM - 11:54AM |
L5.00007: Blue Satellite Bands and Photoassociation near 7$P_{3/2}$ and 7$P_{1/2}$ Atomic Limits in Cesium Marin Pichler, Jianbing Qi, William C. Stwalley, Robert Beuc, Goran Pichler We present observation of atomic self-broadening at ultracold temperatures in cesium near 7$P_{3/2}$ and 7$P_{1/2}$ atomic limits using a MOT and resonant ionization detection. Blue satellite band features were observed at detunings of 560 MHz and 800 MHz. In addition, sharp hyperfine-split photoassociative spectra were observed on the red and blue wings of each line. Given the local maxima in the long range molecular structure (beyond 50 $\AA$), possible explanations of these features are discussed. [Preview Abstract] |
Thursday, May 18, 2006 11:54AM - 12:06PM |
L5.00008: Direct Observation of the Difference of Scattering Phase Shifts Russell Hart, Xinye Xu, Kurt Gibble We directly observe the difference of s-wave scattering phase shifts of Cs atoms in a juggling atomic fountain clock. In our fountain clock, we launch two balls of atoms in rapid succession so that they collide with relative velocities between 5 and 20 cm/s. After launching, the atoms are optically-pumped and cooled to 500 nK with degenerate sideband cooling in a far-detuned optical lattice. One ball, via several microwave transitions and a stimulated Raman transition, is velocity-selected and prepared in a superposition of the two Cs m$_{F}$=0 clock states. This coherent superposition scatters off of the atoms in the other ball, which is prepared in an F=4, m$_{F}$ state. Each atomic state is phase shifted by the scattering. After a second $\pi $/2 pulse, we use a second velocity-selective stimulated-Raman transition to probe the scattered atoms. We vary the phase of the second $\pi $/2 pulse and detect the Ramsey fringes of the scattered atoms. To lowest order, the phase shift of the Ramsey fringes is independent of the atomic density and the interrogation time. [Preview Abstract] |
Thursday, May 18, 2006 12:06PM - 12:18PM |
L5.00009: Measurement of the Photoassociation Rate in a BEC of $^{7}$Li M. Junker, D. Dries, Y. Chen, C. Welford, J. Hitchcock, R. G. Hulet Photoassociation is a process of producing molecules from a collision of two atoms. The maximum rate is limited by quantum mechanical unitarity and by a proposed mechanism involving photodissociation of bound molecules into the contiuum. In the unitarity limit, the rate scales as \textit{n}$\cdot$\textit{T}$^{- 0.5}$. In the photodissociation mechanism, the rate depends on coupling to the quasicontiuum resulting in saturation at high intensities at a value of $\hbar$\textit{n}$^{2/3}/\textit{m}.$\footnote{J. Javanainen and M. Mackie, \textit{Phys. Rev. A} \textbf{59}, R3186 (1999).} The rate of photoassociation has previously been observed to saturate in a non-condensed, but quantum degenerate sample of atomic $^7 $Li to a value consistent with the unitarity limit.\footnote{I. D. Prodan \emph{et al}., \textit{Phys. Rev. Lett.} \textbf{91}, 080402 (2003).} A Bose-Einstein condensate (BEC) is necessary to differentiate between unitarity and photodissociation. We will create a large BEC in an optical dipole trap in the \textit{F}=1, \textit{m}$_{F}$=1 hyperfine state in order to distinguish between these two proposed mechanisms. [Preview Abstract] |
Thursday, May 18, 2006 12:18PM - 12:30PM |
L5.00010: Photoassociative Spectroscopy of Ultracold NaCs Christopher Haimberger, Jan Kleinert, Nicholas P. Bigelow We present photoassociative spectroscopy of excited states of NaCs below the Na(3S1/2)+Cs(6P3/2) asymptote by ionization detection of ground state molecules. States have been observed as far as 31 cm$^{-1}$ from dissociation and as close as 0.1 cm$^{-1}$ from dissociation. We observe as many as 60 ions per ionizer pulse, implying ground state molecule formation rates as high as 100 kHz. [Preview Abstract] |
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