Lifetimes and Self-Quenching Cross Sections of Vibrational Levels in the B State of Bromine Excited by a Tunable Dye Laser

A tunable dye laser was used to excite selected vibrational levels between υ′ = 1 and 31 of the B 3Π0u+ state of Br2. Lifetimes and self-quenching cross sections were measured by observing the direct decay of fluorescence as a function of pressure. Large variations of lifetimes and cross sections were found; the lifetimes varied by a factor of 8, ranging from greater than 1.2 μsec near υ′ = 27 to less than 0.15 μsec near υ′ = 14. Two minima of lifetimes near υ′ = 1 and 14 can be explained by decay of the B state by means of spontaneous predissociation through dissociative states.