• Experimental fundamental transitions for all normal modes should be assigned. Each diatomic molecule is characterized by a single vibrational number, whether all N -atomic molecules for N > 2 (including linear) are characterized with 3N -6 fundamental modes. In the case of the degenerate normal modes, every mode was given. The lowest energy vibration was disregarded for linear molecules, as this additional vibration usually corresponds to a doubly degenerate bending mode.