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What exactly emits the photon? If its the electrons, then shouldn't multiple photons be emitted with the same wavelength?

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- Thread starter n0_3sc
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- #1

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What exactly emits the photon? If its the electrons, then shouldn't multiple photons be emitted with the same wavelength?

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- #3

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When you say the atom "scatters" the photon, does the atom absorb the photon and re-emit it or does the photon literally bounce off the atom?

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When you say the atom "scatters" the photon, does the atom absorb the photon and re-emit it or does the photon literally bounce off the atom?

You have to keep in mind the different ways a photon is scattered.

Let an atom have 2 energy states: initial state 'a' and final state 'b'. Let [itex]\omega[/itex] be the angular frequency in state 'a' and [itex]\omega '[/itex] be the angular frequency of state 'b'. The energies of states a & b are [itex]E_a = \hbar \omega[/itex] & [itex]E_b = \hbar \omega '[/itex] respectively.

The frequency of state a & b are related by the equation:

[tex]\omega ' = \omega + {(E_a - E_b)\over \hbar}[/tex]

[tex] = \omega - \omega_{ba}[/tex]

If [itex]\omega =\omega '[/itex] i.e. emitted frequency is same as incident frequency, we have

Raman Scattering is an example of

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Let an atom have 2 energy states: initial state 'a' and final state 'b'.

I now understand those scattering techniques, but whats confused me even more is the energy states... You say the atom has 2 energy states where you described Rayleigh and Raman scattering - those energy states are the "Virtual" states and not the discrete quantum states of the electrons in the atom correct? So then what are these virtual states? Are they just energy levels that aren't high enough to be a discrete quantum state?

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No, they are discrete quantum states.

...If you are familiar with the selection rules, you know for an atom to emit or absorb a photon the selection rule is [itex]\Delta l = \pm 1[/itex] where 'l' is the angular momentum quantum number.

If they're discrete quantum states then how are they defined?

Yes I am familiar with the selection rules but only for excitation to an electronic state. Sorry I didn't learn much at all from my Q.M. courses...

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http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/raman.html

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