Molecular Vibrations Exercises

As an aid you may wish to use the dos program REDUCE. You can run the program on an Athena machine using the dos emulator "dosemu". Just unzip the REDUCE directory, cd into it, and then type "dosemu REDUCE.EXE" at the command prompt.
  1. Study the experimental gas-phase spectrum of CF4 at the NIST database.
  2. Generate a reducible representation for the vibrations of CF4. This requires first assigning CF4 to the correct point group.
  3. Reduce the reducible representation to its irreducible components. This can be done by inspection or using the program REDUCE. Check that the sum of the characters of the irreducible components is equal to the character of the reducible representation, for each class of symmetry operations.
  4. What is the symmetry species (Mulliken label) of the CF4 molecular vibration(s) that will be infrared active? Explain your answer.
  5. What is the maximum number of bands you expect to observe in the infrared spectrum of CF4, and how does this compare to the experimental data?
  6. Are any of the IR active bands of CF4 also expected to be Raman active? Which one(s)?
  7. Which of the Raman-active bands of CF4 is polarized?
  8. Perform analyses similar to the above CF4 analysis for the molecules PF3, PF5, SO2, S8, XeF4.