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ω e

Learn about Stokes and Anti-Stokes lines, Virtual States, and classical radiation excitation in Raman spectroscopy. Discover how Virtual States are crucial in representing molecular vibrations accurately.

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ω e

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  1. ωe ωe- ωq ωe+ ωq ← ωq → ← ωq → ω→

  2. ωe ωe- ωq ωe+ ωq ω→

  3. ωe Stokes Line Anti-Stokes Line ωe- ωq ωe+ ωq ω→

  4. Generally Weaker ωe Stokes Line Anti-Stokes Line ωe- ωq ωe+ ωq ω→

  5. 0 ωo

  6. 0 ωo

  7. 0 ωo

  8. v Virtual States 0 ωo

  9. v Virtual States 0 ωo

  10. v m 0 ωo

  11. v m 0 ωo- ωm ωo

  12. v m 0 ωo- ωm ωo

  13. v m 0 ωo- ωm ωo ωo+ ωm

  14. v Nm < No …generally so the antistokes Raman lines are generally weaker than the Stokes lines NB in the absence of degeneracy m 0 ωo- ωm ωo ωo+ ωm

  15. v Virtual States ψv = Σcnψn= Σcn n Virtual states may be represented as linear combinations of the complete set of stationary states. Nearby stationary states contributing most. The coefficients cn are inversely proportional to the energy separations ie cn∞ 1/ (Ev – En) ωo

  16. The classical picture is that the incident radiation excites dipolar oscillations in a polarisable system such as a molecule or atom which can act as secondary sources of EM radiation Harry Kroto 2004

  17. P = E E = Eocos2πωt P = Eocos2πωt

  18. P = E E = Eocos2πωt P = Eocos2πωt

  19. P = E E = Eocosωt P = Eocosωt

  20. Attenuation due to scattering by interstellar gas and dust clouds Harry Kroto 2004

  21. Harry Kroto 2004

  22. Harry Kroto 2004

  23. P =  E

  24. P =  E

  25. P =  E

  26. P =  E

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