Limits...
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.


Experimental (red curves) and simulated (blue curves) TOF profiles for ND 3 molecules exiting the Stark decelerator, when a Jordan Valve (left column) or a Nijmegen Pulsed Valve (middle column) is used. The Stark decelerator is operated to guide (ϕ0=0°) a packet of molecules through the decelerator at constant speed, and Ar (panel a-c), Kr (panel d-f), or Xe (panel g-i) is used as seed gas. The selected velocity from the molecular beam pulse, as well as the velocity with which the packet exits the decelerator, is indicated in each panel. The associated ITSs are shown in the right column (solid line: NPV, dashed line: JV)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4527007&req=5

Fig5: Experimental (red curves) and simulated (blue curves) TOF profiles for ND 3 molecules exiting the Stark decelerator, when a Jordan Valve (left column) or a Nijmegen Pulsed Valve (middle column) is used. The Stark decelerator is operated to guide (ϕ0=0°) a packet of molecules through the decelerator at constant speed, and Ar (panel a-c), Kr (panel d-f), or Xe (panel g-i) is used as seed gas. The selected velocity from the molecular beam pulse, as well as the velocity with which the packet exits the decelerator, is indicated in each panel. The associated ITSs are shown in the right column (solid line: NPV, dashed line: JV)

Mentions: We have systematically studied the performance of a JV and NPV as a source for Stark decelerators by recording series of TOFs following the beam loading protocol described above. Figure 5 shows a set of TOFs pertaining to guiding (ϕ0=0°) when the seed gases Ar, Kr and Xe are used. The results for a JV and NPV are shown in the left and middle columns, respectively, whereas the corresponding ITSs are shown in the right column. The peak positions of the ITSs are shifted with respect to T0 for ease of comparison. In all TOFs, an intense central peak is observed that contains the guided bunch of molecules. These peaks show excellent contrast with respect to the signal intensity on either side of this peak.Fig. 5


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

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

Experimental (red curves) and simulated (blue curves) TOF profiles for ND 3 molecules exiting the Stark decelerator, when a Jordan Valve (left column) or a Nijmegen Pulsed Valve (middle column) is used. The Stark decelerator is operated to guide (ϕ0=0°) a packet of molecules through the decelerator at constant speed, and Ar (panel a-c), Kr (panel d-f), or Xe (panel g-i) is used as seed gas. The selected velocity from the molecular beam pulse, as well as the velocity with which the packet exits the decelerator, is indicated in each panel. The associated ITSs are shown in the right column (solid line: NPV, dashed line: JV)
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig5: Experimental (red curves) and simulated (blue curves) TOF profiles for ND 3 molecules exiting the Stark decelerator, when a Jordan Valve (left column) or a Nijmegen Pulsed Valve (middle column) is used. The Stark decelerator is operated to guide (ϕ0=0°) a packet of molecules through the decelerator at constant speed, and Ar (panel a-c), Kr (panel d-f), or Xe (panel g-i) is used as seed gas. The selected velocity from the molecular beam pulse, as well as the velocity with which the packet exits the decelerator, is indicated in each panel. The associated ITSs are shown in the right column (solid line: NPV, dashed line: JV)
Mentions: We have systematically studied the performance of a JV and NPV as a source for Stark decelerators by recording series of TOFs following the beam loading protocol described above. Figure 5 shows a set of TOFs pertaining to guiding (ϕ0=0°) when the seed gases Ar, Kr and Xe are used. The results for a JV and NPV are shown in the left and middle columns, respectively, whereas the corresponding ITSs are shown in the right column. The peak positions of the ITSs are shifted with respect to T0 for ease of comparison. In all TOFs, an intense central peak is observed that contains the guided bunch of molecules. These peaks show excellent contrast with respect to the signal intensity on either side of this peak.Fig. 5

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.