Are diatomic molecules Raman active?

Are diatomic molecules Raman active?

For example, homonuclear diatomic molecules are not IR active, because they have no dipole moment, but they are Raman active. Because of the stretching and contraction of the bond changes the interactions between the electrons and nuclei, this causes a change of polarizability.

What is the selection rule for rotational Raman spectrum of a diatomic molecule?

For Raman spectra the molecules undergo transitions in which an incident photon is absorbed and another scattered photon is emitted. The selection rule for linear molecules is ΔJ = 0, ±2. The reason for the values ±2 is that the polarizability returns to the same value twice during a rotation.

What vibrational modes are Raman active?

All modes of vibrations that belong to the symmetry class of xx, yy, zz, xy, xz, and yz would be Raman active. This simply means that these modes of vibrations or rotations could be observed in Raman spectrum.

Why is N2 Raman active?

A vibration is thus Raman-active if dafdR -=fo 0, that is, the polarisability a of the molecule must change as a function of the internuclear distance R during a vibration. This is always the case for diatomic molecules. For this reason, homonuclear and thus nonpolar molecules such as H2 or N2 are Raman-active.

What type of molecules give rotational Raman spectra?

Rotational Raman spectra have yielded moments of inertia of small symmetric molecules. The most extensive and accurate source by far of moment of inertia data is microwave spectroscopy. This technique is applicable to any polar gaseous molecule.

Which molecule does not give vibrational spectra?

Answer: homonuclear diatomic molecule like H2, O2, N2 etc. which have only stretching motion/ vibrations and no bending motion/vibrations, the dipole moment does not change during vibration. Hence these molecules do not give vibration spectra i.e. they are said to be infrared-inactive.