Eur. Phys. J. D (2022) 76: 34
https://doi.org/10.1140/epjd/s10053-022-00339-0

Regular Article – Optical Phenomena and Photonics

Energy levels and classified lines of 4p²(4f + 5p) configurations of Br III

Department of Physics, Gandhi Faiz-e-Aam College, 242001, Shahjahanpur, U.P., India

^a kriyaz2012@gmail.com, riyaz_ahemad25@yahoo.co.in

Received: 27 September 2021
Accepted: 4 January 2022
Published online: 16 February 2022

Abstract

The 4s²4p² (4f + 5p) configurations of doubly ionized bromine (Br III) have been investigated in the 750–4520 Å wavelength region. The spectrum of bromine in the vacuum ultraviolet wavelength region was photographed on a 3-m normal incidence vacuum spectrograph at the St. Francis Xavier University, Antigonish (Canada) using a triggered spark source. These data were supplemented up to 4600 Å from published results. The structure of Br III is As I-like ion with ground configuration 4s²4p³. The theoretical structure was predicted using Cowan’s configuration interaction (CI) code in HFR mode. The excitations from the ground configuration to 4s4p⁴ + 4s²4p² (4d + 5d + 6d + 5s + 6s + 7s) of even parity system have been investigated recently in our laboratory. In this paper, the second excitations of these excited configurations to 4s²4p² (5p + 4f) in the odd parity system have been studied. Relativistic Hartree–Fock (HFR) and least-squares-fitted parametric calculations have been used to interpret the observed spectrum. Out of 51 possible levels of 4p² (4f + 5p), 49 levels have been established, 39 being new. With current study of 4p² (4f + 5p) configurations, it became possible to established 4 unknown J = 9/2 levels of 4p² (4d & 5d) configurations. Two hundred twenty-five spectral lines are classified.