Emission spectrum of bromine excited in the presence of argon. Part I

Bromine was excited by an uncondensed transformer discharge in the presence of argon. The spectrum obtained was found to be different from what one gets without the presence of a foreign gas and consists of (1) a short discrete band system in the region 3150-2970 Å , (2) an extensive discrete band system in the region 2950-2670 Å , (3) a short and weak discrete system in the region 2660-2590 Å and a set of diffuse bands in the region 3340-3190 Å . The wavelengths and wave numbers of the band heads of the system 2950-2670 Å , as obtained from the measurements of the plates taken on the first order 21-ft. grating spectrograph, are given along with the vibrational analysis. This system is shown to be due to a transition from an upper electronic state at 51802 cm.−1 with ω 'e = 150·5 cm.−1 and ω 'e X'e = 1·15 cm.−1 to the well known3 ∏ a (O2 +) state at 15918 cm.−1