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Old 10-May-2005, 04:58 PM
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Quote:
Originally Posted by Normandy6644
lyndonashmore, you are missing Papageno's point. An electron by itself cannot absorb a photon. It just doesn't happen. When electrons are in bound quantum states (i.e., bound to a nucleus) the atom can absorb the photon, causing the electron to "jump" to another state. When it returns to the ground state it emits a photon of equal energy to the original aborbed photon. That is how it works.
This is what Ashmore calls "on-resonance" absorption.
In response he says:
Quote:
Originally Posted by lyndonashmore
The point is Papageno, that when the frequencies are 'off resonance' in glass atoms the photon is re-emitted.
But even in the "off-resonance" case, the photon is absorbed by the whole system composed of the positive nucleus and the negative electrons.
Being "off-resonance", we effectively cannot see the quantized states, and the system can be treated as a classical electric dipole, which absorbs and re-emits photons.

(See Feynman's Lectures on Physics, Vol. 2, for a treatement of light traveling in dielectric medium.)
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