Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Can a stable gas be ionized by concentrated light?

  1. Aug 28, 2012 #1
    I know that an electron can be brought to a higher energy level when hit by a photon, but if it is hit by several photons, is it possible that it will become no longer attached to the particle?

    This may be a stupid question, I'm not a scientist.
  2. jcsd
  3. Aug 28, 2012 #2
    Yes, for example stars can ionize the hydrogen in interstellar space: http://en.wikipedia.org/wiki/H_II_region

    I may be wrong about this, but I would guess that most such ionization occurs when the atom is hit by a single photon with high enough energy to knock the electron away. Electrons that are only raised to a higher level within the atom very quickly (within nanoseconds or microseconds) fall back down to the lowest energy level.
  4. Aug 28, 2012 #3
    Thanks for your help!
  5. Aug 29, 2012 #4


    User Avatar
    Science Advisor

    This also forms the basis for laser enrichment e.g. of Uranium: Uranium hexafluoride (UF6) is ionized by intense infrared laser light of which many quanta have to be absorbed to lead to ionization. The ionization yield depends on the precise laser frequency and the isotope (238-U vs. 235-U).
  6. Aug 29, 2012 #5


    User Avatar
    2017 Award

    Staff: Mentor

    If the single photon has enough energy, it can ionize the atom directly.

    Several photons at the same time require really high photon densities - something you only get with lasers, but it is possible today.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook