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Register a new userElectrostatic trapping of metastable NH molecules
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We report on the Stark deceleration and electrostatic trapping of $^{14}$NH ($a ^1Delta$) radicals. In the trap, the molecules are excited on the spin-forbidden $A ^3Pi leftarrow a ^1Delta$ transition and detected via their subsequent fluorescence to the $X ^3Sigma^-$ ground state. The 1/e trapping time is 1.4 $pm$ 0.1 s, from which a lower limit of 2.7 s for the radiative lifetime of the $a ^1Delta, v=0,J=2$ state is deduced. The spectral profile of the molecules in the trapping field is measured to probe their spatial distribution. Electrostatic trapping of metastable NH followed by optical pumping of the trapped molecules to the electronic ground state is an important step towards accumulation of these radicals in a magnetic trap.
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Imidogen (NH) radicals are magnetically trapped and their Zeeman relaxation and energy transport collision cross sections with helium are measured. Continuous buffer-gas loading of the trap is direct from a room-temperature molecular beam. The Zeeman relaxation (inelastic) cross section of magnetically trapped electronic, vibrational and rotational ground state imidogen in collisions with He-3 is measured to be 3.8 +/- 1.1 E-19 cm^2 at 710 mK. The NH-He energy transport cross section is also measured, indicating a ratio of diffusive to inelastic cross sections of gamma = 7 E4 in agreement with the recent theory of Krems et al. (PRA 68 051401(R) (2003))
We describe the realization of a dc electric-field trap for ultracold polar molecules, the thin-wire electrostatic trap (TWIST). The thin wires that form the electrodes of the TWIST allow us to superimpose the trap onto a magneto-optical trap (MOT). In our experiment, ultracold polar NaCs molecules in their electronic ground state are created in the MOT via photoassociation, achieving a continuous accumulation in the TWIST of molecules in low-field seeking states. Initial measurements show that the TWIST trap lifetime is limited only by the background pressure in the chamber.
We present experiments on decelerating and trapping ammonia molecules using a combination of a Stark decelerator and a traveling wave decelerator. In the traveling wave decelerator a moving potential is created by a series of ring-shaped electrodes to which oscillating high voltages are applied. By lowering the frequency of the applied voltages, the molecules confined in the moving trap are decelerated and brought to a standstill. As the molecules are confined in a true 3D well, this new kind of deceleration has practically no losses, resulting in a great improvement on the usual Stark deceleration techniques. The necessary voltages are generated by amplifying the output of an arbitrary wave generator using fast HV-amplifiers, giving us great control over the trapped molecules. We illustrate this by experiments in which we adiabatically cool trapped NH3 and ND3 molecules and resonantly excite their motion.
We have recently demonstrated static trapping of ammonia isotopologues in a decelerator that consists of a series of ring-shaped electrodes to which oscillating high voltages are applied [Quintero-P{e}rez et al., Phys. Rev. Lett. 110, 133003 (2013)]. In this paper we provide further details on this traveling wave decelerator and present new experimental data that illustrate the control over molecules that it offers. We analyze the performance of our setup under different deceleration conditions and demonstrate phase-space manipulation of the trapped molecular sample.
We report on the observation of blue-detuned photoassociation in Rb2, in which vibrational levels are energetically above the corresponding excited atomic asymptote. 85Rb atoms in a MOT were photoassociated at short internuclear distances to levels of the (1)3Pi g state at a rate of approximately 5x10^4 molecules/s. We have observed most of the predicted vibrational levels for all four spin-orbit components 0g+, 0g-, 1g, and 2g, including levels of the 0g+ outer well. These molecules decay to the metastable a3Sigma u+ state, some preferentially to the v=0 level, as we have observed for photoassociation to the v=8 level of the 1g component.
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