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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.


Schematic representation of the longitudinal phase-space acceptance of a Stark decelerator for guiding (ϕ0=0°, left) and deceleration (ϕ0=70°, right). The area in phase-space that is occupied by the molecular beam pulse at the entrance of the decelerator is schematically represented by the tilted red ellipse
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Fig2: Schematic representation of the longitudinal phase-space acceptance of a Stark decelerator for guiding (ϕ0=0°, left) and deceleration (ϕ0=70°, right). The area in phase-space that is occupied by the molecular beam pulse at the entrance of the decelerator is schematically represented by the tilted red ellipse

Mentions: To appreciate the various aspects that play a role when coupling the beam into the decelerator, we first discuss the operation principles of the Stark decelerator using the schematic representation in Fig. 2. It is instructive to use phase-space coordinates in the discussion, i.e., the position (z) and velocity (vz) of particles in the longitudinal direction. A proper discussion on the operation principles of Stark decelerators, and an introduction to the relevant terminology such as phase angle ϕ0 and synchronous molecule can be found elsewhere [28, 35]; we here restrict ourselves to the most basic concepts only.Fig. 2


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

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

Schematic representation of the longitudinal phase-space acceptance of a Stark decelerator for guiding (ϕ0=0°, left) and deceleration (ϕ0=70°, right). The area in phase-space that is occupied by the molecular beam pulse at the entrance of the decelerator is schematically represented by the tilted red ellipse
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig2: Schematic representation of the longitudinal phase-space acceptance of a Stark decelerator for guiding (ϕ0=0°, left) and deceleration (ϕ0=70°, right). The area in phase-space that is occupied by the molecular beam pulse at the entrance of the decelerator is schematically represented by the tilted red ellipse
Mentions: To appreciate the various aspects that play a role when coupling the beam into the decelerator, we first discuss the operation principles of the Stark decelerator using the schematic representation in Fig. 2. It is instructive to use phase-space coordinates in the discussion, i.e., the position (z) and velocity (vz) of particles in the longitudinal direction. A proper discussion on the operation principles of Stark decelerators, and an introduction to the relevant terminology such as phase angle ϕ0 and synchronous molecule can be found elsewhere [28, 35]; we here restrict ourselves to the most basic concepts only.Fig. 2

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.