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Quasiparticles,Plasmons,and exotic atoms

  1. Dec 28, 2013 #1
    I'm aware that there are certain unique configurations of atoms often referred to as exotic atoms. One type of these atoms involves the substitution of an electron with a muon in hydrogen. The relatively large mass of the muon results in the size of the hydrogen atom decreasing (which is the basis for the impractical muon-catalyzed fusion).

    Now, a friend of mine claimed that it should be possible to replicate the muon's substitution effect on the hydrogen with a quasiparticle known as a plasmon substituting for the electron. Is it possible for a plasmon to substitute for an electron and form some kind of quasi-atom?

    Also, if it is possible, would it result in the same effect that substituting with a muon would have?

    I know that when substituting with a muon, you can use the same equations that describe normal hydrogen but replace the electron mass with the muon mass. Assuming a quasi-atom was possible, would it need modified equations and what would you use for the mass?

    A big reason I'm skeptical of his claim is because it seems like he's trying to advocate for some kind of alternative fusion method and I'd like to understand this idea so I can critique it.

    Thank you for any help in understanding this matter.
  2. jcsd
  3. Dec 28, 2013 #2


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    Looks like plasmons are massless, and do not have a charge. Both things make an orbit around an ion impossible.
    In addition, I doubt plasma oscillations happen on a scale as small as a hydrogen atom. I guess that would need a really high plasma frequency (>>10 eV).
  4. Dec 29, 2013 #3
    I figured it must be something like that. I just wasn't familiar with the concept of a plasmon.
  5. Dec 29, 2013 #4
    Read the 3rd sentence of the Wiki entry: "Plasmons are collective oscillations of the free electron gas..."

    You cannot take a plasmon out of a metal or glass or whereever it occurs and try to build an atom from it. That would be like trying to take a wave out of the ocean to make a water molecule from it.

    The same goes for all other elementary excitations of solids: Phonons, Excitons, even holes in a semiconductor. These are emergent phenomena that "live" in the solid.
  6. Dec 30, 2013 #5


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    You cannot remove it from a solid, but inside a solid it behaves very similar to a particle. Plasmons don't have the right properties to bind to atoms, but that is not a fundamental result of their quasi-particle nature.

    Holes can be trapped at specific locations in the material, for example.
  7. Dec 30, 2013 #6
    Yes, an exciton is kind of like an atom out of a hole and an electron, but much much larger than a "normal" atom.

    A muon is a real particle (as much as anything is real in QM), and you can quite literally take a mu- and a proton to make an Hydrogen-like atom with much smaller size than normal Hydrogen with e- and proton. With a quasi-particle you cannot do that.

    Take for example a band-electron of a heavy-fermion material. The effective mass of this quasi-particle electron is huge. It also has the right charge. Yet you cannot take it out of the material to make a super-small atom with it because it is an emergent property of the solid - even if within the solid, to very very good approximation it behaves like a particle.
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