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Optimal beam sources for Stark decelerators in collision experiments: a tutorial review.

Vogels SN, Gao Z, van de Meerakker SY - EPJ Tech Instrum (2015)

Bottom Line: The performance of two valves in particular, the Nijmegen Pulsed Valve and the Jordan Valve, is illustrated by decelerating ND 3 molecules in a 2.6 meter-long Stark decelerator.We describe a protocol to characterize the valve, and to optimally load the pulse of molecules into the decelerator.We characterize the valves regarding opening time duration, optimal valve-to-skimmer distance, mean velocity, velocity spread, state purity, and relative intensity.

View Article: PubMed Central - PubMed

Affiliation: Radboud University, Institute for Molecules and Materials, Heijendaalseweg 135, AJ Nijmegen, 6525 Netherlands.

ABSTRACT

With the Stark deceleration technique, packets of molecules with a tunable velocity, a narrow velocity spread, and a high state purity can be produced. These tamed molecular beams find applications in high resolution spectroscopy, cold molecule trapping, and controlled scattering experiments. The quality and purity of the packets of molecules emerging from the decelerator critically depend on the specifications of the decelerator, but also on the characteristics of the molecular beam pulse with which the decelerator is loaded. We consider three frequently used molecular beam sources, and discuss their suitability for molecular beam deceleration experiments, in particular with the application in crossed beam scattering in mind. The performance of two valves in particular, the Nijmegen Pulsed Valve and the Jordan Valve, is illustrated by decelerating ND 3 molecules in a 2.6 meter-long Stark decelerator. We describe a protocol to characterize the valve, and to optimally load the pulse of molecules into the decelerator. We characterize the valves regarding opening time duration, optimal valve-to-skimmer distance, mean velocity, velocity spread, state purity, and relative intensity.

No MeSH data available.


Arrival time distributions of NO radicals seeded in Ar, produced by an NPV (left) or JV (right) positioned at a distance of 87 mm from the interaction region. At selected arrival time positions, indicated by the letters A,B,C (NPV) or a,b,c (JV), the mean speed and velocity spreads of the packets are measured using velocity map imaging
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Fig8: Arrival time distributions of NO radicals seeded in Ar, produced by an NPV (left) or JV (right) positioned at a distance of 87 mm from the interaction region. At selected arrival time positions, indicated by the letters A,B,C (NPV) or a,b,c (JV), the mean speed and velocity spreads of the packets are measured using velocity map imaging

Mentions: In Fig. 8, the arrival time distributions are shown for beams of NO seeded in Ar when the NPV (left panel) or the JV (right panel) is used. Arrival time distributions with widths (FWHM) of 20 μs and 45 μs are found for the NPV and the JV, respectively. Clearly, the opening time of the NPV is much narrower compared to the JV. The mean speed of the molecules along the opening time duration of both valves is measured by recording the velocity distribution of the NO packets at the selected arrival times indicated in the figure. The resulting VMI images, referred to as beamspots, are shown for both valves in the lower part of Fig. 8.Fig. 8


Optimal beam sources for Stark decelerators in collision experiments: a tutorial review.

Vogels SN, Gao Z, van de Meerakker SY - EPJ Tech Instrum (2015)

Arrival time distributions of NO radicals seeded in Ar, produced by an NPV (left) or JV (right) positioned at a distance of 87 mm from the interaction region. At selected arrival time positions, indicated by the letters A,B,C (NPV) or a,b,c (JV), the mean speed and velocity spreads of the packets are measured using velocity map imaging
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4527007&req=5

Fig8: Arrival time distributions of NO radicals seeded in Ar, produced by an NPV (left) or JV (right) positioned at a distance of 87 mm from the interaction region. At selected arrival time positions, indicated by the letters A,B,C (NPV) or a,b,c (JV), the mean speed and velocity spreads of the packets are measured using velocity map imaging
Mentions: In Fig. 8, the arrival time distributions are shown for beams of NO seeded in Ar when the NPV (left panel) or the JV (right panel) is used. Arrival time distributions with widths (FWHM) of 20 μs and 45 μs are found for the NPV and the JV, respectively. Clearly, the opening time of the NPV is much narrower compared to the JV. The mean speed of the molecules along the opening time duration of both valves is measured by recording the velocity distribution of the NO packets at the selected arrival times indicated in the figure. The resulting VMI images, referred to as beamspots, are shown for both valves in the lower part of Fig. 8.Fig. 8

Bottom Line: The performance of two valves in particular, the Nijmegen Pulsed Valve and the Jordan Valve, is illustrated by decelerating ND 3 molecules in a 2.6 meter-long Stark decelerator.We describe a protocol to characterize the valve, and to optimally load the pulse of molecules into the decelerator.We characterize the valves regarding opening time duration, optimal valve-to-skimmer distance, mean velocity, velocity spread, state purity, and relative intensity.

View Article: PubMed Central - PubMed

Affiliation: Radboud University, Institute for Molecules and Materials, Heijendaalseweg 135, AJ Nijmegen, 6525 Netherlands.

ABSTRACT

With the Stark deceleration technique, packets of molecules with a tunable velocity, a narrow velocity spread, and a high state purity can be produced. These tamed molecular beams find applications in high resolution spectroscopy, cold molecule trapping, and controlled scattering experiments. The quality and purity of the packets of molecules emerging from the decelerator critically depend on the specifications of the decelerator, but also on the characteristics of the molecular beam pulse with which the decelerator is loaded. We consider three frequently used molecular beam sources, and discuss their suitability for molecular beam deceleration experiments, in particular with the application in crossed beam scattering in mind. The performance of two valves in particular, the Nijmegen Pulsed Valve and the Jordan Valve, is illustrated by decelerating ND 3 molecules in a 2.6 meter-long Stark decelerator. We describe a protocol to characterize the valve, and to optimally load the pulse of molecules into the decelerator. We characterize the valves regarding opening time duration, optimal valve-to-skimmer distance, mean velocity, velocity spread, state purity, and relative intensity.

No MeSH data available.