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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.


Simulated time-of-flight profiles for ND 3 molecules exiting the Stark decelerator for guiding (ϕ0=0°, left column) and deceleration (ϕ0=50°, right column) when the opening time of the pulsed valve is 20 μs (a and b), 50 μs (c and d) or 100 μs (e and f)
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Fig4: Simulated time-of-flight profiles for ND 3 molecules exiting the Stark decelerator for guiding (ϕ0=0°, left column) and deceleration (ϕ0=50°, right column) when the opening time of the pulsed valve is 20 μs (a and b), 50 μs (c and d) or 100 μs (e and f)

Mentions: Indeed, an important criterium for the use of Stark-decelerated beams in crossed beam scattering experiments is the ability to produce a wide range of velocities with a TOF contrast that is similar to the ones presented in Fig. 3. Let’s therefore have a closer look at the influence of the valve opening time τ on the quality of the TOF profiles. Figure 4 shows TOF profiles that result from numerical trajectory simulations of different deceleration processes. These simulations pertain to the experimental conditions as present in the TOFs of Fig. 3, i.e., v0=435 m/s and ϕ0 is either 0° (left column) or 50° (right column). Three different valve opening times are used in the simulations: τ= 20 μs (panels a and b), τ= 50 μs (panels c and d), and τ= 100 μs (panels e and f). These are representative values for τ for an NPV, JV, and GV, respectively.Fig. 4


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

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

Simulated time-of-flight profiles for ND 3 molecules exiting the Stark decelerator for guiding (ϕ0=0°, left column) and deceleration (ϕ0=50°, right column) when the opening time of the pulsed valve is 20 μs (a and b), 50 μs (c and d) or 100 μs (e and f)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig4: Simulated time-of-flight profiles for ND 3 molecules exiting the Stark decelerator for guiding (ϕ0=0°, left column) and deceleration (ϕ0=50°, right column) when the opening time of the pulsed valve is 20 μs (a and b), 50 μs (c and d) or 100 μs (e and f)
Mentions: Indeed, an important criterium for the use of Stark-decelerated beams in crossed beam scattering experiments is the ability to produce a wide range of velocities with a TOF contrast that is similar to the ones presented in Fig. 3. Let’s therefore have a closer look at the influence of the valve opening time τ on the quality of the TOF profiles. Figure 4 shows TOF profiles that result from numerical trajectory simulations of different deceleration processes. These simulations pertain to the experimental conditions as present in the TOFs of Fig. 3, i.e., v0=435 m/s and ϕ0 is either 0° (left column) or 50° (right column). Three different valve opening times are used in the simulations: τ= 20 μs (panels a and b), τ= 50 μs (panels c and d), and τ= 100 μs (panels e and f). These are representative values for τ for an NPV, JV, and GV, respectively.Fig. 4

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.