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Absorption of energy from a photon?

  1. Sep 8, 2008 #1
    Hey guys, am studying light and matter at the moment.

    Was just wondering:

    1. Assuming an atom requires 3.2 eV to transfer an electron to an excited state, if a photon of 3.3eV struck the atom, would it still be absorbed. If so, what happens to the remaining energy
  2. jcsd
  3. Sep 9, 2008 #2
    Interesting question... I was pondering about it myself some time ago. One thing is that the energy of the excited state isn't exact, but it has a certain spread due to the Heisenberg uncertainty, so the photon energy doesn't need to be exactly the same as that of the excited level. I guess that the greater the difference between photon energy and excited level, the less probability that the photon will be absorbed. Thus, all energy will be absorbed, if it's absorbed at all.
  4. Sep 9, 2008 #3
    From what I learnt, it won't get absorbed.
    Unless 3.2eV's the energy required for ionisation... Then if the photon has energy greater than this ionisation energy, it will get absorbed and the remaining energy will be transferred to kinetic energy.
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