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How to view light absorption by atoms

  1. Oct 5, 2009 #1
    the way i understand it is photons excite atoms, causing them to increase in energy. i view this increase in energy as jostling of a atom causing more movement of its proton, neutrons, electrons.

    i realize a photon is a particle and a wave(in limited comprehension.)

    so should i view the transfer for energy as a vibration(wave form of light) traveling then hits a medium(atom), causing a vibration as it passes through?

    or should i view this as a particle passing through passing through a systems(atoms) orbit. much like a rogue planet passing through a solar system effects caused by gravity possible collision?

    or neither?
  2. jcsd
  3. Oct 5, 2009 #2
    A photon is an electrical field wave, it affects the electron motion as an electric force. If electron initially turns around a nucleus in a round orbit (a circle), then, after receiving a push from a photon, its orbit gets elliptic.
  4. Oct 5, 2009 #3
    A single photon is fundamentally a particle, but in quantum mechanics this means it does not necessarily have a precise position or momentum; it’s smeared out in some sense. But you can make it so that the position and momentum are reasonably localized. Electrons (and any other fundamental particle with electric charge) interact with a photon in a fundamental way. In the case of the atom, an electron and photon meet and we are left with just the electron, but with a larger energy (absorption). The nucleus does not take part in this situation.

    Incidentally, the planetary picture of an atom is not generally so good. This is because, as in the previous paragraph, the electron according to quantum mechanics doesn’t have a precise position or momentum, though the amount of the smearing depends on the physical situation. In the case of typical atomic orbits, the electron is delocalized around the nucleus, so it doesn’t make sense to say it’s orbiting like a planet (in the case of a Rydberg atom—see Wikipedia—an outer electron can be approximately pictured like this, though).

    Note that both the electron and photon are particles but have “wave properties” according to quantum mechanics. In the case of the photon, the wavelike properties were brushed aside by saying we could try to start with a photon localized it in a reasonable region of space, while the electron’s wavelike property could not be ignored, and in its atomic orbital it is delocalized.
  5. Oct 5, 2009 #4
    so its actually movement(in form of a wave or vibration) of the fields charged objects produce?
    so the photons would wash over the matter in wave form only affecting charged objects. any photon in collision with a electron is absorbed.

    why do photons not effect protons?

    sorry for all the questions i am trying to do as much research on my own as possible, to cut down on the questions, it kinda makes more sense if i think about it like gravity.
    Last edited: Oct 5, 2009
  6. Oct 5, 2009 #5
    also it doesnt matter the direction the photon approaches, the electron always increases in energy?
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