BOND-DISSOCIATION ENERGIES OF PBBR2(G) AND THE DYE LASER-INDUCED FLUORESCENCE EXCITATION SPECTRUM OF PBBR(A-X)

An equilibrium thermodynamics determination of the individual bond dis sociation energies in PbBr2(g) is presented, yielding 66.5 +/- 3.5 and 59.4 +/- 3.5 kcal/mol for the successive removal of Br atoms. These r esults are based on atomic absorption measurements of Pb(g) number den sities and laser-induced fluorescence measurements of relative PbBr(g) number densities in equilibrium with PbBr2(g) at temperatures between 700 and 850 degrees C. The laser-induced fluorescence excitation spec trum of PbBr(A-X), excited between 467 and 485 nm and observed between 516 and 536 Mm, is reported. Lifetime measurements of PbBr(A) at vari ous PbBr2 number densities yielded a collision-free lifetime of simila r to 200 ns and a PbBr2 collisional quenching constant of 1.42 x 10(-9 ) cm(3) molecule(-1) s(-1).