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I am trying to grasp the difference between Raman scattering and fluorescence.
To me it appears that the former is described in a somewhat more classical context as ordinary inelastic scattering, while the latter actually has a meaningful quantum mechanical description.
So what is the quantum explanation for Raman scattering? I have read it involves a "virtual state" as an intermediate state. What is that supposed to mean?
If it just means (extremely) short lifetime, then there should be a mixed regime between Raman scattering and fluorescence, but I have never heard about that.
How does one calculate the virtual state if it "exists"?

This question is focused on the mathematics behind Raman scattering. How does one formulate Raman scattering of a photon and an atom, we may for simplicity assume that we have a hydrogen atom. e.g given some electronic state, how do I calculate the virtual states involved with Raman scattering?

Jim
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iolo
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1 Answers1

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The main difference between the two is the time scale, as you've already discussed a bit in your question. The other main Physical difference is that fluorescence is the result of relaxation from an electronic state, whereas Raman scattering is the result of relaxation from vibrational states.

A virtual state is a shortlived state that can't be described particularly well, you can't define its occupation for example. You can however define a lifetime for them using the uncertainty relations, which I'm guessing is what the source of the short timescales involved in Raman scattering.

kw111
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