When is a vibrational mode of a molecule Raman active?
A) When the vibrational mode has the same symmetry as a component of the molecule's electric dipole moment vector.
B) When the vibrational mode has the same symmetry as a component of the molecule's polarizability.
C) Vibrational modes of molecules are Raman active only; they cannot be IR active at the same time

Question

Quizplus · Accepted Answer

A vibrational mode is Raman active if it involves a change in the polarizability of the molecule. This is because Raman scattering is a process that depends on the polarizability of the molecule changing as it vibrates. The symmetry of the vibrational mode and its effect on the molecule's polarizability tensor determine whether the mode is Raman active.

When Is a Vibrational Mode of a Molecule Raman Active