Deceleration and trapping of ammonia molecules in a traveling-wave decelerator

Jansen, Paul; Quintero‐Pérez, Marina; Wall, T. E.; Berg, J. E. van den; Hoekstra, Steven; Bethlem, Hendrick L.

doi:10.1103/physreva.88.043424

Cited by 23 publications

(29 citation statements)

References 29 publications

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“…Both traveling-wave Stark [24,25] and Zeeman [26][27][28][29] decelerators have been successfully demonstrated. Recently, first experiments in which the decelerated molecules are subsequently loaded into static traps have been conducted [30,31].…”

Section: Introductionmentioning

confidence: 99%

Multistage Zeeman decelerator for molecular-scattering studies

Cremers¹,

Chefdeville²,

Janssen³

et al. 2017

Phys. Rev. A

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We present a concept for a multistage Zeeman decelerator that is optimized particularly for applications in molecular beam scattering experiments. The decelerator consists of a series of alternating hexapoles and solenoids, that effectively decouple the transverse focusing and longitudinal deceleration properties of the decelerator. It can be operated in a deceleration and acceleration mode, as well as in a hybrid mode that makes it possible to guide a particle beam through the decelerator at constant speed. The deceleration features phase stability, with a relatively large six-dimensional phase-space acceptance. The separated focusing and deceleration elements result in an unequal partitioning of this acceptance between the longitudinal and transverse directions. This is ideal in scattering experiments, which typically benefit from a large longitudinal acceptance combined with narrow transverse distributions. We demonstrate the successful experimental implementation of this concept using a Zeeman decelerator consisting of an array of 25 hexapoles and 24 solenoids. The performance of the decelerator in acceleration, deceleration, and guiding modes is characterized using beams of metastable helium ( 3 S) atoms. Up to 60% of the kinetic energy was removed for He atoms that have an initial velocity of 520 m/s. The hexapoles consist of permanent magnets, whereas the solenoids are produced from a single hollow copper capillary through which cooling liquid is passed. The solenoid design allows for excellent thermal properties and enables the use of readily available and cheap electronics components to pulse high currents through the solenoids. The Zeeman decelerator demonstrated here is mechanically easy to build, can be operated with cost-effective electronics, and can run at repetition rates up to 10 Hz.

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Section: Introductionmentioning

confidence: 99%

Multistage Zeeman decelerator for molecular-scattering studies

Cremers¹,

Chefdeville²,

Janssen³

et al. 2017

Phys. Rev. A

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“…The experiments described in this paper are performed in a vertical molecular beam machine that was used earlier to decelerate and trap ammonia molecules [10,19,20]. A mixture of 5% methylfluoride molecules in xenon is released into vacuum using a pulsed valve (General Valve Series 9) that is cooled to 173 K, resulting in a beam with an average velocity of around 315 m/s and a velocity spread of 60 m/s.…”

Section: Methodsmentioning

confidence: 99%

“…If, on the other hand, the temperature of the cloud is essentially the same as the trap depth, a large loss will occur when the voltages are lowered only slightly. Note that if the voltages are lowered slowly, the molecules are also cooled adiabatically; the velocity spread of the trapped molecules is lowered at the expense of an increased position spread [10,19,20]. Figure 3(a) shows the result of such an experiment.…”

Section: Temperature and Density Of Trapped Methylfluoride Moleculesmentioning

confidence: 99%

Femtosecond laser detection of Stark-decelerated and trapped methylfluoride molecules

et al. 2015

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Here we report on the accumulation of ground-state NH molecules in a static magnetic trap. A pulsed supersonic beam of NH (a 1 ∆) radicals is produced and brought to a near standstill at the center of a quadrupole magnetic trap using a Stark decelerator. There, optical pumping of the metastable NH radicals to the X 3 Σ − ground state is performed by driving the spin-forbidden A 3 Π←a 1 ∆ transition, followed by spontaneous A → X emission. The resulting population in the various rotational levels of the ground state is monitored via laser induced fluorescence detection. A substantial fraction of the ground-state NH molecules stays confined in the several milliKelvin deep magnetic trap. The loading scheme allows one to increase the phase-space density of trapped molecules by accumulating packets from consecutive deceleration cycles in the trap. In the present experiment, accumulation of six packets is demonstrated to result in an overall increase of only slightly over a factor of two, limited by the trap-loss and reloading rates.

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“…The long lifetimes increase the probability that interactions can take place before the molecules are ejected from the trap by collisions with background gas or by photon scattering [4]. There have been many recent experiments that have explored various electrostatic [7][8][9][10] and magnetic [11][12][13] trapping geometries, and others that demonstrated additional in-trap cooling [14][15][16][17][18][19]. Importantly, several experiments have taken advantage of trapped molecules to study the properties of the molecules themselves, including vibrational relaxation of OH [20] and NH [21].…”

Section: Introductionmentioning

confidence: 99%

Measurements of trap dynamics of cold OH molecules using resonance-enhanced multiphoton ionization

et al. 2017

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Trapping cold, chemically important molecules with electromagnetic fields is a useful technique to study small molecules and their interactions. Traps provide long interaction times that are needed to precisely examine these low density molecular samples. However, the trapping fields lead to non-uniform molecular density distributions in these systems. Therefore, it is important to be able to experimentally characterize the spatial density distribution in the trap. Ionizing molecules in different locations in the trap using resonance enhanced multiphoton ionization (REMPI) and detecting the resulting ions can be used to probe the density distribution even with the low density present in these experiments because of the extremely high efficiency of detection. Until recently, one of the most chemically important molecules, OH, did not have a convenient REMPI scheme identified. Here, we use a newly developed 1 + 1' REMPI scheme to detect trapped cold OH molecules. We use this capability to measure trap dynamics of the central density of the cloud and the density distribution. These types of measurements can be used to optimize loading of molecules into traps, as well as to help characterize the energy distribution, which is critical knowledge for interpreting molecular collision experiments.

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Deceleration and trapping of ammonia molecules in a traveling-wave decelerator

Cited by 23 publications

References 29 publications

Multistage Zeeman decelerator for molecular-scattering studies

Multistage Zeeman decelerator for molecular-scattering studies

Femtosecond laser detection of Stark-decelerated and trapped methylfluoride molecules

Measurements of trap dynamics of cold OH molecules using resonance-enhanced multiphoton ionization

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