Resonance series of Br2 in the vacuum ultraviolet

A high-resolution resonance fluorescence spectrum of bromine excited by an electrical discharge in the region 1500–2100 Å was photographed on a 10.7-m concave grating vacuum spectrograph. Twelve resonance doublet series excited by four bromine atomic resonance lines were identified and analyzed. All doublet series have the ground state of ^79,81Br₂ as the lower electronic state. The vibrational numbers of these doublets corresponding to this state vary from 0 to 76. Rotational constants are obtained by least-squares fitting of the doublet separations, and the vibrational constants by least-squares analysis of vibrational term values. Probable assignments for the upper electronic state(s) of the transitions involved were suggested.