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  Rotational Raman Spectroscopy
Centrifugal Distortion page 1 of 3
Practical Navigator
The Raman Effect
Experimental Techniques
1. Rotational Raman Spectroscopy
Interpreting the Spectrum
Effect of Bond Length
Centrifugal Distortion
Intensities of Spectral Lines
Nuclear Spin Statistics
2. Real Diatomic Molecules
Spectrum of Nitrogen
Isotopic Substitution
Nuclear Spin Statistics
Predict the Spectrum of Oxygen
  The effect of centrifugal distortion is to destroy the constant separation of the spectral lines. Separations increase line spacing in one half of the spectrum and decrease it in the other.

The molecule cannot be a strictly rigid rotor because we know that molecules vibrate. A better model for representing the rotation of the molecule is the non-rigid rotor in which two masses are attached by a massless spring.

Q3.1 What is the centrifugal force on a particle rotating in a circular path?
Q3.2 In which direction is the force?
Q3.3 How can equilibrium be maintained in the molecule?
Q3.4 How would you expect this to affect the rotational energy levels?

The energy levels of the non-rigid rotor are approximated by the equation:
F(J) = BJ(J+1) - DJ(J+1) (9)

Q3.5 Derive equations for the positions of the Stokes and Anti-Stokes lines.
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