Journal of Physical Chemistry, Vol.98, No.7, 1864-1867, 1994
Production and Decay of PBI(G) from the 308-nm Photodissociation of Pbi2(G)
An extensive investigation of the production and decay of ground-state PbI(g) molecules from the 308-nm XeCl excimer laser photodissociation of PbI2(g) is reported. The laser fluence dependence of the PbI yield along with energetic considerations suggests that PbI is produced by a one-photon process. PbI decay profiles as a function of argon pressure, PbI2 pressure, laser fluence, and cell temperature were determined. These results suggest that PbI and the other likely photodissociation product, I, decay back to PbI2 by a complex mechanism involving an exothermic preequilibrium. We propose a complex mechanism that includes the PbI2 catalyzed recombination of PbI and I and the dimerization of PbI molecules. The proposed mechanism also takes into account the presence of Pb formed from the two-photon photodissociation of PbI2 and is capable of reproducing the observed PbI(g) and Pb(g) decay profiles under most conditions studied when : reasonable values of rate constants for the various elementary steps are used.
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