An Analysis of the E(0g+) Ion-pair State of Bromine through Stepwise Excitation Technique

Abstract
The pulses of the fundamental and its frequency doubled outputs from a tunable dye laser are used to promote a stepwise exciation of the E(0g+)–X1Σg+ transition through the B3Π(0u+) state in molecular bromine. The double resonance is detected by the associated UV emission which originates from the E(0g+) state radiating back to the B3Π(0u+) state. The E(0g+) state is analyzed in detail on the basis of the selection rules of two transition components and the E–B fluorescence spectrum. The molecular parameters are derived as Te=49778.5 cm−1, ωe=150.8 cm−1, ωexe=0.41 cm−1, and re=3.197 Å for the 79Br2 isotope species.