Study of electronic absorption spectrum of hafnium monobromide molecule in the 550–800 nm region

Abstract

The electronic absorption spectrum of the HfBr molecule in the 550–800 nm region is studied using the intracavity laser spectroscopy method. The HfBr molecules are produced in plasma formed during a pulse electric discharge in the vapor mixture of hafnium tetrabromide with hydrogen or ammonium. The discharge tube with the mixture is placed in a dye laser cavity. The spectrum recording is conducted with the help of a diffraction spectrograph (resolution power 240000). The high sensitivity of the intracavity method makes it possible to reveal the presence of twenty new bands in the HfBr spectrum with partially resolved rotational structure. By analogy with the HfCl spectrum, the HfBr bands are assigned to the ²Δ_3/2–X²Δ_3/2 transition. Analysis of the bands is conducted and molecular constants are determined for the ground and excited states:ω_e'' = 255.07 cm^–1, ω_eω_e''= 0.86 cm^–1, ω_e'= 238.31 cm^–1, ω_eω_e'= 1.1 cm^–1, B'' = 0.04251 cm^–1, B' = 0.04025 cm^–1.