Predissociation in the First Positive Group of Nitrogen

Abstract

THE electronic level diagram of the normal N₂ molecule is shown in Fig. 1. The horizontal full lines represent the different electronic levels, the dotted lines the dissociation states; known transitions between the different molecular levels are represented by vertical arrows, whereas the electronic levels are connected by brackets with the atomic states into which they dissociate. As the position of the singlet levels relatively to the triplet ones is still rather uncertain, the zero of the scale of volts has been put at the triplet level A₃. The dissociation states of the different molecular levels have already been given by various workers, of whom especially J. Kaplan must be named¹. By his observation of the predissociation in the B³II level of the first positive group (transition B³II A³) at v = 12 and v = 20, he was able to give strong evidence in favour of the diagram. Predissociation in the C³II-level was first observed by G. Herzberg² and studied in detail by D. Coster, F. Brons and A. v. d. Ziel³. They interpreted this predissociation as due to the ²D + ²D dissociation state, as was also done by Kaplan.