Classical Theory of Raman Effect: Molecular Polarizability
The basic concept of classical theory of the Raman effect depends on the polarizability of a molecule and the applied Electric field.When a molecule is placed in a static electric field, a distortion takes place in it because of the attraction of positively charged nuclei towards negative pole of the field and of electron towards positive pole. This separation of charge centers causes an induced electric dipole moment in the molecule and the molecule becomes polarized. The magnitude of induced dipole (𝜇) depends both on magnitude of the applied field (E) and on the case with which the molecule can be distorted. Thus,
𝜇 = 𝛼E
where α is the polarizability of the molecule.
In case of hydrogen molecule, the polarizibility is anisotropic i.e. the electron that form the bond are more easily displaced by the field along the bond axis than along the one across this direction.
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