Repulsive Energy Levels in Band Spectra

An explanation is given for many cases of anomalous intensity distribution in the band spectra of diatomic molecules. Use is made of an interaction between the known energy levels of molecules and energy levels which are produced by the repulsive interaction of pairs of atoms in their normal and metastable energy levels. The chief types of anomalies which are discussed are those corresponding to the sudden cutting off of a group of bands at some low value of $v^{\prime }$, the initial vibrational quantum number, and the failure of bands to agree with the Franck-Condon theory. Use is made of these ideas to explain the long life of active nitrogen.