Cold and intense OH radical beam sources

Ploenes, Ludger; Haas, Dominik; Zhang, Dongdong; Meerakker, Sebastiaan Y. T. van de; Willitsch, Stefan

doi:10.1063/1.4948917

Cited by 20 publications

(26 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At this temperature, the mean thermal velocity of helium is about 460 m/s. The ELV nozzle is replaced by a discharge source consisting of alternating isolated and conducting plates, similar to the source described by Ploenes et al [50]. The discharge occurs between the conducting plates, where the front plate is kept at −600 V and the back plate is grounded.…”

Section: B Metastable Helium Beammentioning

confidence: 99%

Multistage Zeeman decelerator for molecular-scattering studies

Cremers¹,

Chefdeville²,

Janssen³

et al. 2017

Phys. Rev. A

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: B Metastable Helium Beammentioning

confidence: 99%

Multistage Zeeman decelerator for molecular-scattering studies

Cremers¹,

Chefdeville²,

Janssen³

et al. 2017

Phys. Rev. A

Self Cite

View full text Add to dashboard Cite

show abstract

“…The velocity of a radical beam can be coarse-tuned by using different carrier gases. In a previous study [42], we showed that OH beam velocities around 670 m/s, 485 m/s and 385 m/s can be obtained with Ar, Kr and Xe as carrier gases in our discharge source. Note that the carrier gas also influences the properties and plasma chemistry of the discharge and therefore the density of radicals produced.…”

Section: Velocity Of the Radical Beammentioning

confidence: 65%

“…[42], using Kr as carrier gas yields an initial OH beam density a factor 2 to 3 lager than with Xe. The higher initial density for OH in Kr compared to Xe can be seen by comparing the TOF profiles obtained in guiding mode (i.e., 0 = 0°) displayed as insets in Fig.…”

Section: Velocity Of the Radical Beammentioning

confidence: 96%

“…In this section, we briefly describe the characteristics of a discharge radical source based on the "Nijmegen pulsed valve" (NPV) [41,42] employed in our experiments.…”

Section: Radical Sourcesmentioning

confidence: 99%

“…The NPV has proven to be a reliable pulsed gas source capable of delivering high intensity beams at short valve opening times (a few tens of μs) [41]. Building on these favorable characteristics, a pinhole-discharge source has recently been developed in our laboratory to accompany the NPV [42]. A cross section of the assembly is shown in Fig.…”

Section: Radical Sourcesmentioning

confidence: 99%

See 2 more Smart Citations

Optimizing the density of Stark decelerated radicals at low final velocities: a tutorial review

et al. 2017

Self Cite

View full text Add to dashboard Cite

The Stark deceleration technique can produce molecular beams with very low velocities. In order to maximize the density of decelerated molecules, experimental parameters such as the velocity, the velocity spread and the spatial spread of the initial molecular beam as well as the operation characteristics of the decelerator have to be chosen appropriately. In this tutorial review, we describe procedures for the optimization of the density of Stark decelerated radicals for low-velocity applications which are of interest in, e.g., molecule trapping and cold-collision studies. Keywords: Cold molecules, Molecular beams, Stark deceleration, Radicals ReviewTranslationally cold molecules have become an attractive subject of research in recent years. A number of techniques for the generation of cold molecules has been developed [1-5] among which Stark deceleration is one of the most important [3,[6][7][8]. This method finds a broad range of applications in spectroscopy [9][10][11][12], collision-dynamics studies [13][14][15][16][17][18][19][20][21][22][23][24][25][26] and trap loading experiments [27][28][29][30][31][32][33]. The principle of Stark deceleration has been well documented [2,3], and a number of operation schemes have been developed for the optimization of Stark-decelerated molecular beams in different types of experiments [34][35][36][37].A Stark decelerator employs time-varying inhomogeneous electric fields produced by an array of dipolar electrodes to slow down pulsed beams of polar molecules [3,6]. When a packet of molecules approaches a set of electrodes, they are switched to high electric potential. Molecules in low-field-seeking Stark states experience a force which reduces their kinetic energy. The voltages on the electrodes are switched off before the molecules reach the maximum of the dipole potential in order to prevent their re-acceleration after they have passed the electrodes. This procedure is repeated at every pair of electrodes along the decelerator until the molecules have reached their target velocity at the exit of the assembly.The final velocity of the packet of molecules is controlled by a parameter referred to as phase angle 0 which corresponds to a scaled position of a "synchronous molecule" at which the high voltages on the electrodes of the decelerator are switched. Successful

show abstract

Low-Energy Collisions of Zeeman-Decelerated NH Radicals with He Atoms

Plomp¹,

Lique

Meerakker³

2023

J. Phys. Chem. A

Self Cite

View full text Add to dashboard Cite

We report an experimental study of state-to-state inelastic scattering of NH (X 3 Σ − , N = 0, j = 1) radicals with He atoms. Using a crossed molecular beam apparatus that combines a Zeeman decelerator and velocity map imaging, we study both integral and differential cross sections in the N = 0, j = 1 → N = 2, j = 3 inelastic channel. We developed various new REMPI schemes to state-selectively detect NH radicals, and tested their performance in terms of sensitivity and ion recoil velocity. We found a 1 + 2′ + 1′ REMPI scheme using the A 3 Π ← X 3 Σ − resonant transition, which yields acceptable recoil velocities and is more than an order of magnitude more sensitive than conventional onecolor REMPI schemes to detect NH. We used this REMPI scheme to probe state-to-state integral and differential cross sections around the channel opening at 97.7 cm −1 , as well as at higher energies where structure in the scattering images could be resolved. The experimental results are in excellent agreement with the predictions from quantum scattering calculations which are based on an ab initio NH-He potential energy surface.

show abstract

Cold and intense OH radical beam sources

Cited by 20 publications

References 38 publications

Multistage Zeeman decelerator for molecular-scattering studies

Multistage Zeeman decelerator for molecular-scattering studies

Optimizing the density of Stark decelerated radicals at low final velocities: a tutorial review

Low-Energy Collisions of Zeeman-Decelerated NH Radicals with He Atoms

Contact Info

Product

Resources

About