Band Contours of Asymmetric Rotors Infrared spectra of the vapors of asymmetric rotor molecules frequently show unresolved band contours. These contours are of value in assigning fundamental vibrational frequencies t o symmetry species. In the course of investigations of the vibrational assignments of odadeuteronaphthalene, it was noted that a striking example of band contours is present in the infrared spectrum. This illustrates well the use of band contours in making vibrational assignments. An asymmetric rotor is a molecule having three distinct moments of inertia: IA