1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Ground state

  1. Feb 6, 2014 #1
    Just curious: if an electron absorbs a photon of energy, it is in an excited state. The electron may go to a lower energy state (but NOT the ground state). Can a photon (of higher wavelength than absorbed) be emitted still?

    I don't quite see the importance of the electron having to go to the ground state in this case...
  2. jcsd
  3. Feb 6, 2014 #2


    User Avatar

    Staff: Mentor

    Do you mean a longer wavelength, or a higher frequency? A "higher wavelength" doesn't make sense.

    In any case, an electron can exist above the ground state, absorb a photon, and then fall to a lower state than what it was occupying emitting a photon of higher frequency than what it absorbed in the process.
  4. Feb 7, 2014 #3
    Isn't a higher wavelength proportional to lower energy? How would it emit a higher energy photon (i.e. higher frequency) than what it absorbed?

    So to confirm, a photon can still be emitted despite the electron not decaying to its ground state, just any state lower than its excited state, correct?
  5. Feb 7, 2014 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    A photon can be emitted if the system goes from a higher energy state to a lower energy state (not necessarily the ground state), and if it abides by the selection rule.

    Example: the Balmer lines in H atom.

    Last edited: Feb 7, 2014
  6. Feb 7, 2014 #5


    User Avatar

    Staff: Mentor

    The extra energy required to emit a photon of higher frequency than the electron absorbs comes from the extra energy it already had by being in a state above the ground state.

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook