Photodissociation of Br2 in the visible continuum

The photodissociation of Br2 in the region 434–511 nm has been studied using the technique of laser induced photodissociation spectroscopy. Following photolysis of Br2 with a tunable dye laser, production of bromine atoms in the electronically excited, 42P1/2, and ground, 42P3/2, states was monitored by observing the attenuation of the atomic resonance emission line, 52P3/2→42P3/2, at 148.9 nm. Analysis of the absorption profiles yielded the relative contribution to the visible continuum of the B 3Π0+u←X 1Σg+ transition. Estimates of the absolute absorptivity for the transitions 1Πlu, B 3Π0 +u, A 3Πlu←X 1Σg+ were obtained by application of the reflection principle. These results are in excellent agreement with previous direct measurements but suggest that models of the Br2 absorption continuum which neglect the A 3Πlu←X 1Σg+ transition are likely to be in error.