Band systems in the spectrum of nitrogen

Several new band systems of N2 which have been reported by us independently during the war are compared. Several systems have been obtained by both of us, and agreement is generally satisfactory. There appear to be eight progressions of bands in the ultra-violet which are due to transitions to the a1Π state. Differing vibrational analyses for the Fifth Positive (Van der Ziel) system are discussed, and it is shown that Gaydon's interpretation is to be preferred, while for Kaplan's Second system (Herman's a) Herman's vibrational analysis is more satisfactory. Bands in the green region are compared.