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

B Can you ionize metal with photons?

  1. Jul 11, 2018 #1
    The photoelectric effect occurs when light causes electrons to fly off atoms. An equal number of electrons to protons gives an atom a net charge of 0. If I left a piece of metal in the sun for a long time, that would mean a large number of electrons would fly off. This should, in theory, give the part of the metal exposed to sunlight a positive net charge

    NOTE: Although I say in theory, the purpose of this post is not to debate a theory. Rather, I am trying to understand a question that I cannot resolve.
  2. jcsd
  3. Jul 11, 2018 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2018 Award

    When I did photoemission spectroscopy experiments many years ago, we have to make very sure that the photocathode is properly grounded. If not, we will run into what is known as the charging effect, i.e. the material that we want to study (i.e. the photocathode) becomes charged because it cannot replenish the electrons lost via photoemission.

    So yes, something that is isolated (metal, semiconductor) and undergoes photoemission WILL become charged.

    A metal left in the sun, if it is just the visible spectrum, will not typically be charged because visible light does not have enough energy to overcome the typical work function of a metal. Besides, a charge metal left out in the open can usually grab charges from other things in the air or from cosmic radiation.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?