Revised and extended analysis of Br IV

- The spectrum of Br was recorded on a 3-m spectrograph with triggered spark source.
- Atomic transitions for Br IV were identified to established new energy levels.
- CI calculations with relativistic corrections were made for theoretical predictions.
- Weighted oscillator strength (gf) and transition probabilities (gA) were calculated.
- Ionization potential of Br IV was determined experimentally.

The spectrum of three-times ionized bromine Br IV has been studied in the 319-2350 Å wavelength region. The spectrum was recorded on a 3-m normal incidence vacuum spectrograph at the St. Francis Xavier University, Antigonish (Canada) and 6.65-m grazing incidence spectrograph at the Zeeman laboratory (Amsterdam). The light sources used were a triggered spark and sliding spark, respectively. The ground configuration of Br IV 3d104s24p2, the excited configurations 3d104s4p3+3d104s24p (4d+5d+6d+5s+6s+7s) in the odd parity system and 3d104s24p (5p+4f+5f)+3d104s4p2 (4d+5s)+3d104p4 in the even parity system have been studied. Relativistic Hartree-Fock (HFR) and least squares fitted (LSF) parametric calculations were used to interpret the observed spectrum. 120 Levels of Br IV have now been established, 58 being new. Among 424 spectral lines, 277 are newly classified. The levels 4s4p35S2, 4s24p4d 3F4 and 4p5p (3P0, 1, 3D1, 2, 3S1) are revised. We estimate the accuracy of our measured wavelength for sharp and unblended lines to be ±0.005 Å. The ionization limit is determined as 385,390±100 cm−1 (47.782±0.012 eV).