CHEM 442 Lecture 34 Problems
34-1. Starting from the transition dipole moment, derive the gross and specific selection
rules of pure rotational absorption transitions of a linear rotor.
34-2. A microwave absorption spectrum of a diatomic molecule is illustrated below.
Explain why there are many spectral lines and why they are roughly evenly spaced.
34-3. A close inspection of the spectrum of 34-2 reveals that the line spacing becomes
slightly narrower at higher energies. Explain why.
34-4. Explain why the intensities of the lines in 34-2 initial increases with energy and
then turn to decrease, creating a bell-shaped envelope.
34-5. What are the gross and specific selection rules of pure rotational Raman scattering
of a linear rotor?
34-6. Which of microwave spectroscopy or Raman spectroscopy should you use to
determine the rotational constants of N2, O2, H2O, CO2, Ar, and CH4?
34-7. Draw a pure rotational Raman spectrum of a linear rotor. Name the three branches,
explain their relative intensities, rationalize the shape of branch envelope, and give line
spacing in terms of the rotational constant B.
34-8. What are para and ortho H2?
34-9. The figure below is an illustration of the rotational Raman spectrum of H2. Explain
the 3:1 intensity alternation.