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Mechanism of reflection at the atomic scale

  1. Sep 28, 2009 #1

    I'm currently looking into reflectivity and emissivity of metals in sunlight. However, I can't quite grasp how the mechanisms of reflection and emission differ. Emission obviously occurs because an electron is exited by a photon and then is de-excited and emits photon or photons. However I don't see how reflection is different when looked at on the atomic scale?

    Anyway if anyone has an explanation please let me know!

  2. jcsd
  3. Sep 28, 2009 #2


    Staff: Mentor

    Reflection doesn't happen at the atomic scale. Optical light has wavelengths much much larger than an atom. For radiation that is down close to the atomic scale you typically get scattering and ionization, not reflection. It doesn't make sense to me to talk about reflection at the atomic scale because for reflection to occur you need a smooth surface and no surface is smooth at the atomic scale.
  4. Sep 29, 2009 #3
    metals reflect because they are conductors
  5. Nov 12, 2009 #4
    Why do conductors reflect?
  6. Nov 12, 2009 #5
    Transitions between quantum stationary states are not the only kind of emission that is possible (consider the continuous spectra of reflections and black body radiation, versus the quantised "atomic" lines). Reflection has to do with polarisability of a material; at the atomic scale it involves a small perturbation of the electron cloud rather than a jump to a completely different orbital shape.

    Would you say that specular reflection, diffuse reflection and scattering are like planets, planetoids and asteroids? (In other words, I think your absolute statement is just defining your terms rather than describing a physical process. Even considering reflection as some emergent/aggregate phenomena, isn't the OP still valid in asking what is going on down to the atomic level within a larger piece of material?)

    That is answered in detail in (classical) electrodynamics textbooks.
    Last edited: Nov 12, 2009
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