How to slow down a high energy neutral molecular beam

[BillKet]

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?

 

[DrClaude]

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.

 

[BillKet]

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.

 

[Twigg]

I think if you had such a technique, many institutions around the world would be eager to hire you 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.

 

[berkeman]

(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