How to slow down a high energy neutral molecular beam

In summary, it is possible to slow down molecular beams with electric fields and magnetic fields, but it is difficult to do so.
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BillKet
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Hello! I see that in experiments at facilities like ISOLDE, they produce molecular beams at energies of tens of keV. If I understand it right, they first create the molecule as a positive ion, and using electric fields (and maybe magnetic for mass selection) they take the particle out of the source with an energy of a few keV. Then they neutralize the molecule in flight and then perform spectroscopy on the neutral molecule. I was wondering if there is a way to slow down a neutral beam with such high energy? I assume one can also slow it down before neutralization, but as far as I understand the neutralization process happens by collision with a certain gas, and at low energies these collisions would significantly change the properties of the beam (such as direction, energy spread or energy levels distribution), so I assume that is not an option?
 
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  • #3
DrClaude said:
There are different methods than can be used to slow down molecular beams, such as lasers, Stark decelerators, and Zeeman slowers.

I don't know which method they use for ISOLDE.
Thank you for your reply. I looked at these methods, but they are used to slow down molecules at very small energies (for example for beams coming out of a buffer gas cells). The beams in the experiments I am asking about have many orders of magnitude more energy.
 
  • #4
I think if you had such a technique, many institutions around the world would be eager to hire you :oldbiggrin: I haven't heard of anyone slowing any neutral beam faster than a supersonic jet (with Stark decelerators, as @DrClaude mentioned), and that's still on the meV scale.
 
  • #5
(sorry for my B-level response in this A-level thread, but...)

Would it be possible to ionize the neutral particle beam and then apply electrostatic braking and then recombine the two charged beams? Or would that only work for supersonic-velocity beams? Maybe the particles moving with 10s of keV would not spend enough time in the ionization region of the apparatus?

https://www.osti.gov/servlets/purl/7327888
 
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Related to How to slow down a high energy neutral molecular beam

1. How does a high energy neutral molecular beam travel?

A high energy neutral molecular beam travels at a very high speed in a straight line, similar to a laser beam. It is composed of neutral molecules that have been accelerated to high velocities.

2. Why would someone want to slow down a high energy neutral molecular beam?

Slowing down a high energy neutral molecular beam is necessary for certain experiments and applications, such as studying molecular collisions or creating thin films. Slowing down the beam allows for more precise control and measurement of the molecules' interactions.

3. What methods can be used to slow down a high energy neutral molecular beam?

There are several methods that can be used to slow down a high energy neutral molecular beam, including using a buffer gas, passing the beam through a series of magnetic fields, or using a laser beam to cool the molecules.

4. How does using a buffer gas slow down a high energy neutral molecular beam?

When a high energy neutral molecular beam collides with a buffer gas, it transfers some of its energy to the gas molecules. This reduces the speed of the beam and allows for better control and manipulation of the molecules.

5. Are there any potential risks or challenges associated with slowing down a high energy neutral molecular beam?

Yes, there are potential risks and challenges associated with slowing down a high energy neutral molecular beam. These can include technical difficulties in setting up the necessary equipment, potential contamination of the beam by the buffer gas, and the possibility of altering the behavior of the molecules being studied. It is important to carefully plan and execute the slowing down process to minimize these risks.

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