Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session N9: Cold and Ultracold Molecules II |
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Chair: Kisra Egodapitiya, Georgia Institute of Technology Room: 556AB |
Thursday, May 26, 2016 10:30AM - 10:42AM |
N9.00001: Trapping and Sympathetic Cooling of Boron Hydride Ions RENE RUGANGO, Mudit Sinhal, Gang Shu, Kenneth Brown We demonstrate the trapping and sympathetic cooling of BH$^{+}$ ions in a Coulomb crystal of laser-cooled Ca$^{+}$, which we non-destructively confirm by resonantly exciting the secular motion of the molecular ion. The BH$^{+}$ ions are loaded by ablating boron in presence of H$_{2}$ which also produces various molecular ions of the form B$_{x}$H$_{y}^{+}$ as side products. This mixture of sympathetically cooled molecular ions can then be used to perform molecular spectroscopy. Our goal is to control the internal degrees of freedom of BH$^{+}$ as a first step towards the direct Doppler cooling of a molecular ion. [Preview Abstract] |
Thursday, May 26, 2016 10:42AM - 10:54AM |
N9.00002: Stopping intense beams of internally cold molecules via centrifugal forces Xing Wu, Thomas Gantner, Martin Zeppenfeld, Sotir Chervenkov, Gerhard Rempe Cryogenic buffer-gas cooling produces intense beams of internally cold molecules [1]. It offers a versatile source for studying collision dynamics and reaction pathways in the cold regime, and could open new avenues for controlled chemistry, precision spectroscopy, and exploration of fundamental physics. However, an efficient deceleration of these beams still presents a challenge. Here, we demonstrate that intense and continuous beams of electrically guided molecules produced by a cryogenic buffer-gas cell [2] can be brought to a halt by the centrifugal force in a rotating frame [3]. Various molecules (e.g. $CH_3F$ and $CF_3CCH$) are decelerated to below $20m/s$ at a corresponding output intensity of $\sim6\times10^9 mm^{-2}\cdot s^{-1}$. In addition, our RF-resonant depletion detection shows that up to $90\%$ rotational-state purity can be achieved in the so-produced slow molecular beams.\\ \\ $^1$J. D. Weinstein et al., Nature 395, 148 (1998)\\ $^2$L.D. van Buuren et al., Phys. Rev. Lett. 102, 033001 (2009)\\ $^3$S. Chervenkov et al., Phys. Rev. Lett. 112, 013001 (2014) [Preview Abstract] |
Thursday, May 26, 2016 10:54AM - 11:06AM |
N9.00003: Optical slowing of calcium monofluoride molecules Aakash Ravi, Eunmi Chae, Boerge Hemmerling, Loic Anderegg, Benjamin Augenbraun, Garrett Drayna, Nicholas Hutzler, Alejandra Collopy, Yewei Wu, Shiqian Ding, Jun Ye, Wolfgang Ketterle, John Doyle We report white-light slowing of calcium monofluoride molecules. A single main laser (606 nm) plus two additional vibrational repump lasers (628 nm) are employed. The slowing lasers are spectrally broadened to address the molecules' velocity spread and hyperfine splittings. We use a background-free two-photon fluorescence detection scheme to make high signal-to-noise measurements of our molecular beam's longitudinal velocity distribution. This method is applied to slow CaF produced by a two-stage cryogenic buffer gas beam source by $>$ 30 m/s to near the capture velocity of a molecular magneto-optical trap (MOT). Due to the presence of magnetic dark states which inhibit optical cycling, we will use an AC-MOT. We characterize the performance of this AC-MOT used in the trapping of Li and Yb. [Preview Abstract] |
Thursday, May 26, 2016 11:06AM - 11:18AM |
N9.00004: Submillikelvin Dipolar Molecules in a Radio-Frequency Magneto-Optical Trap Matthew Steinecker, Eric Norrgard, Daniel McCarron, Michael Tarbutt, David DeMille The rich level structures of diatomic molecules enable a wide range of experiments in ultracold chemistry, precision measurement, and quantum simulation, but this same structure poses challenges in laser cooling and trapping [1,2]. Here we present a scheme for magneto-optically trapping SrF molecules by rapidly and synchronously reversing the trapping laser polarizations and the applied magnetic field gradient to destabilize optical dark states [3]. We achieve trapping of SrF at temperatures one order of magnitude lower and phase-space densities 3 orders of magnitude higher than obtained previously with laser-cooled molecules. The number of molecules and trap lifetime are also improved by loading the trap with high laser power and then reducing the power for long-term trapping. With this procedure, temperatures as low as 400 $\mu $K are achieved. We are currently pursuing several approaches to increase the phase-space density of the trapped sample, including applying sub-Doppler cooling and improving the efficiency of the laser slowing stage, prior to loading the molecules into a conservative trap. [1] J. F. Barry \textit{et al.}, \textit{Nature} \textbf{512}, 286--289 (2014). [2] D. J. McCarron \textit{et al.}, \textit{New J. Phys.} \textbf{17}, 035014 (2015). [3] E. B. Norrgard \textit{et al.}, arXiv:1511.00930, to appear in \textit{Phys. Rev. Lett.} [Preview Abstract] |
Thursday, May 26, 2016 11:18AM - 11:30AM |
N9.00005: Spectroscopic measurement of the titanium-helium van der Waals molecule: TiHe Nancy Quiros, Naima Tariq, Jonathan Weinstein Atoms that are weakly bound by the van der Waals (vdW) interaction are known as van der Waals molecules. The existence and formation of vdW molecules is favorable at low temperatures due to their weak binding energy. We have used laser ablation and helium buffer gas cooling to create the exotic vdW diatomic molecule made of titanium (Ti) and helium (He). TiHe molecules were detected through laser-induced-fluorescence spectroscopy closely blue-detuned from the $a\ ^3F_2 \rightarrow y\ ^3F_3$ atomic Ti transition at 25227 cm$^{-1}$. Measurements of the binding energy of TiHe were obtained by studying its equilibrium thermodynamic properties. It is believed the molecules are formed from the constituent cold atoms through three-body recombination. Progress towards measuring the three-body recombination rate coefficient will be discussed. [Preview Abstract] |
Thursday, May 26, 2016 11:30AM - 11:42AM |
N9.00006: Chiral analysis and mixtures of cold, large molecules Sandra Eibenberger, Garrett K. Drayna, Kenneth Wang, Christian Hallas, John M. Doyle, David Patterson We show new avenues for ultra-specific chemical analysis of buffer-gas cooled molecules via microwave spectroscopy. Buffer gas cooling provides a continuous, mixture compatible, solution compatible source, where the cold environment is controllable and the cooling process is separate from the production of the gas phase molecules [1,2]. We demonstrate the analysis of complex molecular mixtures by introducing a new liquid injection source with microwave spectroscopy in a cryogenic buffer gas environment.\\ Chirality plays a fundamental role in the activity of many biological molecules and in broad classes of chemical reactions. Recently, we have demonstrated species and enantiomer sensitive microwave spectroscopic methods [3,4]. We seek to apply these methods not just to the analysis of chemical mixtures, but also to the manipulation of mixtures.\\ \\ 1. N. R. Hutzler, H.-I Lu, and J. M. Doyle. Chem. Rev. 112 (9), 4803 (2012)\\ 2. G. K. Drayna, K. Wang, C. Hallas, S. Domingos, S. Eibenberger, J. M. Doyle, D. Patterson. Ang. Chem. Int. Ed. (2016), doi: 10.1002/anie.201600030\\ 3. D. Patterson, M. Schnell, & J. M. Doyle. Nature 497, 475-477 (2013)\\ 4. D. Patterson & J. M. Doyle. Phys. Rev. Lett. 111, 023008 (2013)\\ [Preview Abstract] |
Thursday, May 26, 2016 11:42AM - 11:54AM |
N9.00007: Quantum control of ultracold NaK polar molecules in optical traps Ming Li, Alexander Petrov, Constantinos Makrides, Svetlana Kotochigova Selection of trapping conditions with ultracold molecules, where internal states experience identical trapping potentials, brings substantial benefits for the ultimate control of their internal degrees of freedom. Here we present our work on the control of NaK molecules, when they are subjected to both trapping laser light and external electric and magnetic fields. First, we calculated parallel and perpendicular polarizabilities using a coupled-cluster method at the CCSD level. This enables us to determine the differential Stark shifts of rotational levels of NaK as a function of orientation of external fields. The hyperfine and Zeeman structure of these rotational states was obtained using an effective spin Hamiltonian. We find that under the experimental conditions with NaK~[1], the hyperfine sublevels of the $J=1$ rotational state are significantly mixed by the trapping laser light so that the simplified model of Ref.~[2] for ``magic'' conditions can not be applied. Adding a modest static electric field, however, can minimize the mixing of magnetic sublevels and make it easier to find ``magic'' conditions. [1] J. W. Park et al. Phys. Rev. Lett. 114, 205302 (2015) [2] B. Neyenhuis et al. Phys. Rev. Lett. 109, 230403 (2012) [Preview Abstract] |
Thursday, May 26, 2016 11:54AM - 12:06PM |
N9.00008: ABSTRACT WITHDRAWN |
Thursday, May 26, 2016 12:06PM - 12:18PM |
N9.00009: Spin relaxation in ultracold collisions of molecular radicals with alkali-metal atoms Timur Tscherbul, Jacek Klos, Piotr Zukowski We present accurate quantum scattering calculations of spin relaxation in ultracold collisions of alkali-metal atoms and polar $^2\Sigma$ molecules CaH, SrF, and SrOH. The calculations employ state-of-the-art ab initio interaction potentials and a rigorous quantum theory of atom-molecule collisions in a magnetic field based on the total angular momentum representation. We will further discuss the relevance of the results to atom-molecule sympathetic cooling experiments in a magnetic trap. [Preview Abstract] |
Thursday, May 26, 2016 12:18PM - 12:30PM |
N9.00010: ABSTRACT WITHDRAWN |
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