Studies of the Bromine Spectrum and Determination of Transition Probabilities for Br I and Br II Lines

In a wall-stabilized cascade arc at atmospheric pressure in mixtures of argon and bromine vapors thermal plasmas were generated. Arc currents between 25 and 60 A were used. Applying a spectrometer of medium dispersion, equipped with an optical multichannel analyzer (CCD detector), the spectra of neutral and singly ionized bromine in the range between 3300 and 10400 Å were recorded. Line intensity measurements, corrected for self-absorption, at different operating conditions of the arc, were performed. A complete set of Br I transitions (5 lines) originating from a common upper level (branching fractions) was measured. In the case of the Br II spectrum intensities of 14 lines were determined. Both sets of lines (Br I and Br II) were normalized to an absolute scale using appropriate lifetime values. The uncertainties of the new determined transition probabilities depend mainly on the uncertainties of the lifetime data taken from the literature. The results are compared to other experimental data. Discrepancies are found to be outside of uncertainties of the measurements.