Vacuum ultraviolet resonance spectrum of Br₂ molecule

Abstract

A new series of resonance doublets in the region 1860-1565 Å has been identified in the spectrum of Br₂. The spectrum was excited in a mildly condensed transformer discharge through flowing bromine vapor and photographed with a 3-meter normal incidence vacuum grating spectrograph. Analysis of the series suggests that the bromine atomic line, 63497.8 cm⁻¹ excites the molecules from v" = 1, J" = 61 level of the ground state to J' = 62 rotational level of a v' vibrational level of an upper electronic state, from which the molecules go over to the different levels of the ground state with the emission of the observed resonance series. The molecular constants of the ground state of Br₂ according to this analysis are (in cm⁻¹): and The observed resonance series has been shown to be due to the Br⁷⁹Br⁸¹ molecule. Probable assignments for the upper state of the transition involved have been suggested.