Question

4. Which set of lines is weaker, Stokes or anti-Stokes? What effect would raising the temperature have on the intensity of Stokes and antiStokes lines?

Answer 1

Actually, anti stokes lines are weaker than stokes lines. Usually, the intensity of line is depending on the number of population at that level. Since, stokes lines are from ground state ( very huge amount of particles) and anti stokes lines are from excited state (comparably less number of particles) .

Therefore, the raising the temperature would decrease the population of the ground state and increase the population of higher energy vibrational states. Therefore, with increased temperature, the intensity of the Stokes lines would decrease and the intensity of the anti-Stokes lines would increase. However, the Stokes lines would still have higher intensity than the anti-Stokes lines.