1.   Ground-state vibration frequencies are obtained as shifts from the exciting frequency or from the vibrational origin of the electronic band.

2.   Indeed, no relationship between the vibration frequencies of different molecules is logically necessary.

3.   Molecular vibrations therefore lead to oscillations of electric charge, with frequencies governed by the normal vibration frequencies of the system.

4.   The minimum in the potential function is at a greater internuclear distance, and the vibration frequency is lower.

5.   The random differences in environment result in a range of different vibration frequencies, and so each vibration band is broadened.