Question

a) What is the difference between resonance and non-resonance Raman transitions?

b) What is the difference between Rayleigh scattering, Raman-Stokes, and Raman-AntiStokes scattering?

c) Schematically plot IR spectra of a N^2, 14^NO and 15^NO. List all differences between these spectra. How many translational, rotational and vibrational degrees of freedom are in these molecules?

d) Sketch the potential that more accurately represents vibrations in diatomic molecules and compare it to the harmonic potential. Compare the energies in both cases. List all differences.

Answer 1

a)

In Resonance Raman scattering, the incident radiation is at a frequency near the frequency of an electronic transition of the molecule of interest. This provides enough energy to excite the electrons to a higher electronic state. The absorbed radiation is emitted (scattered ) from the excited electronic state at a slightly different energy than the incident radiation

In Non-resonance Raman scattering the increase in energy from the radiation is not sufficient to excite the electron to a higher electronic state but sufficient to excite the electrons to an unstable virtual state. Therefore, the interaction is almost immediately discontinued and the radiation is emitted (scattered) at a slightly different energy than the incident radiation.

b) In Rayleigh scattering,the frequency of the scattered radiation is equal to that of the incident radiaton,

In Raman scattering,the frequency of the scattered radiation is different from that of the incident radiaton,

If the frequency of the scattered radiation is less than that of the incident radiation, the resulting Raman lines are known as Stokes lines

If the frequency of the scattered radiation isgreater than that of the incident radiation, the resulting Raman lines are known as Anti-Stokes lines

Please post the remaiing questions as new questions