Answer:
Rotational spectroscopy, the dipole moment must change during the transition.
Rotational Raman spectroscopy, molecule must have anisotropic polarizability
Vibrational and electronic spectroscopy, molecule must have permanent dipole moment.
Step-by-step explanation:
- For the vibration rotation spectrum to be observed, it is necessary to change the dipole moment during the vibration.
- Raman scattering using an anisotropic crystal gives information about the orientation of the crystal. The polarization of Raman scattering light relative to the crystal, and the polarization of laser light, can be used to determine the orientation of the crystal, provided the crystal structure is known.