Spectroscopy of BaBr Rotational analysis of the A²Π-X²Σ⁺ and B²Σ⁺-X²Σ⁺ transitions of the ¹³⁸Ba⁸¹ Br isotopomer

Abstract

The first rotational analysis of BaBr has been performed. The near-infrared A²π-X²Σ⁺ and B²Σ⁺-X²Σ⁺ band systems of BaBr were recorded in absorption by using Fourier transform spectroscopy (FTS). Laser induced fluorescence spectra from both systems obtained by exciting with a Ti: sapphire single mode laser were recorded with FTS techniques in order to simplify the otherwise dense spectra. No direct combination difference approach was possible in order to analyse the absorption bands in detail, why the rotational line measurements were processed using semiautomatic iterative routines for synthesizing and evaluating molecular spectra. Resolved rotational data consisting of around 5000 lines of ¹³⁸Ba⁸¹Br, originating from 10 vibrational bands including the vibrational levels ν=0–2 of the A²π and X²Σ⁺ states and ν=0–1 of the B²Σ⁺ state, were used in the final analysis. The observed anomalous intensity distribution and the interaction between the A²π and B²Σ⁺ states are discussed.