An Optical-optical Double Resonance Excitation of Bromine to a New D(0u+) Ion-pair State

Abstract

Abstract An optical-optical double resonance (OODR) technique utilizing a sequential three-photon absorption has been applied to study the electronic structure of Br2. Two pulsed dye lasers were used to excite the molecules to appropriate rovibronic levels of the B3Π(0u+) state and subsequently into an ion-pair state by simultaneous two-photon transition. The OODR excitation spectra showed a number of transitions consisting of closely-spaced O, Q, and S branches which combine the B3Π(0u+) state with a new ion-pair state designated D(0u+). The following spectroscopic constants of the D(0u+) state were determined for the 79Br2 isotope species: Te=49925.4(6), ωe=135.7(3), ωexe=0.27(3), Be=0.04190(14), and αe=5.9(23)×10−5 cm−1.