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Electrons in a beam of light

  1. Sep 15, 2015 #1
    Can electrons be "guided" or "carried" by a beam of light, something in the manner of how a ship can be guided by a current? So suppose we emit a uniform field of electrons. I don't know if field is the right word. I mean a bunch of electrons of more or less uniform distribution are being shot at a wall that is capable of detecting them. When we detect the electron strikes on this wall, we unsurprisingly find a uniform distribution. Now introduce a thin beam of light shining down the center of this distribution of electrons, towards the wall, and run the experiment again. Will this beam of light have any effect on how the electrons travel and how they strike the wall? Will there, for instance, be a greater density of electrons detected where the light is shining?

    I am asking because it seems like an electromagnetic wave shined in the path of a moving charge should have some effect on the trajectory of the charge. And I'm wondering if this kind of mechanism could be used to guide or aim a charge?

    Thanks for your help!
  2. jcsd
  3. Sep 15, 2015 #2


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    Staff: Mentor

    Are you familiar with free electron lasers (FELs)?
  4. Sep 16, 2015 #3
    I just Wiki'd it. Thanks for the reference.

    But it looks like this is a device for shooting or guiding a beam of electrons using some kind of magnetic tube. I was wondering if something similar could be accomplished with a beam of light, so the electron would run along the path of the light, rather than along the length of a magnetic-field-tube.
  5. Sep 16, 2015 #4


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    It depends on the setup. The light can scatter at the electrons, reducing both the photon and the electron density at the wall in the bright spot (as both get transverse momentum).
    That's the opposite of "guiding".

    For (small) macroscopic objects, things can be more interesting - you can move them around by manipulating a beam of light. See optical tweezers.
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