Two new weak band systems have been identified under high resolution in the near ultraviolet emission spectrum of molecular nitrogen. They are found to arise from a transition from a hitherto unknown 1Πg state, which it is proposed to call k, to the a′ 1Σu− and w1Δu states. The upper state is interpreted as the 1ΠgRydberg state of configuration … (1πu)4 (3σg) 3dπg. Straightforward treatment of the data by conventional methods gives B0d = 1.906 cm−1, B1d = 1.824 cm−1, T0 = 113 630.87 cm−1, and ΔG1/2 = 2305.92 cm−1. Only the d levels, i.e., the levels corresponding to the 1Πg− component, are observed and the absence of the c levels is attributed to an unusual type of predissociation involving the predicted stable 1Σg+ state which goes to the dissociation limit 2D + 2D (14.522 eV) and the 3Σg− state which arises at the limit 4S + 2P (13.332 eV). A new level at 117 661.11 cm−1 with a Bd value of 1.695 cm−1 is identified as v = 2 of the y1Πg state. A strong homogeneous interaction is found to be occurring between the new k1Πg state and the y1Πg state. A deperturbation calculation is carried out and yields the following deperturbed constants: k1Πg: Be = 1.959 cm−1; αe = 0.031 cm−1; re = 1.109 Å; T0 = 113 723.58 cm−1; ΔG1/2 = 2182.32 cm−1, y1Πg: Be = 1.739 cm−1; αe = 0.017 cm−1; re = 1.177 Å; Te = 114 314.36 cm−1; ωe = 1906.43 cm−1; αexe = 37.51 cm−1.
