Time-resolved studies of emission from I2(B3Πou+)

Abstract

The emission from I₂(B³Π_ou+)→I₂(X¹Σ⁺_g)+hv has been monitored following the flash photolysis of CF₃I. The study of the emission from this banded system using a rapid scan spectrometer shows that it commences approximately at the onset of the B–X continuum and that continuous emission resulting from the two-body recombination of I(5²P_½) and I(5²P_3/2), into which the B state resolves, is not important. Thus the emission in the banded region results from the production of I₂(B) by recombination in the presence of a third body according to I(5²P_½)+ I(5²P_3/2)+ M →I₂(B)+ M. There is no contribution from an inverse predissociation mechanism for which the energy barrier would be large. The rate equation for the concentration of I₂(B) can be solved with a number of experimentally justifiable assumptions and the time-dependent concentrations of the ground state and excited atoms derived from previous observations on spin orbit relaxation. Thus the variation of the I₂(B—X) emission, monitored at a single wavelength, can be correlated with the kinetics of I(5²P_½) and I(5²P_3/2).