Revised and extended analysis of trebly ionized bromine: Br IV

The spectrum of Br IV has been studied in the wavelength region 320-1290 A based on the recordings made on a 3-m normal incidence spectrograph at Antigonish Laboratory and on a 6.65-m grazing incidence spectrograph at Zeeman Laboratory, Amsterdam.The light sources used were a triggered spark and sliding spark, respectively. The 4s24p2-[4s4p3+4s24p (4d+5d+6d+5s+6s+7s)] transition array has been investigated using Hartree-Fock (HF) and least squares fitting (LSF) parametric calculations. Previous analysis has been revised and extended considerably. A value of 1S0 level of the ground configuration 4s24p2 has been found at 33575.5 cm-1. One hundred and forty-two lines have been classified in this spectrum to establish 61 energy levels out of which 43 are new. The wavelength accuracy of our measurements for sharp lines is ±0.005 A. A revised value of the ionization potential of Br IV has been found to be 385 400±250 cm-1 (47.77±0.03 eV).