Emission spectrum of bromine excited in the presence of argon

The wavelengths and wavenumbers of the band heads of the system 2660-2590 Å as obtained from the plates taken on the first order 21-feet grating spectrograph are given along with its vibrational analysis. This system is shown as the transition from an upper state at T _e =56776 cm.^?1 withω _e = 108·0 cm.^?1 to the³ Π _u (O _u ⁺) state at T _e =15918 cm.^?1 The lower state is the same as that of the two systems in the regions 2950-2670 Å and 3150-2970 Å reported earlier.