Interpretations of XeI and XeBr bound–free emission spectra and reactive quenching of Xe(3P2) atoms by bromine and iodine containing molecules

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Abstract
The XeBr and XeI emissions spectra have been recorded in a flowing afterglow apparatus from the reaction of Xe(3P2) atoms with 16 bromine and iodine containing reagents. In all cases both the B and C states of XeI and XeBr are observed; the inital B/C ratio is ∼1.5. The ratio increase with pressure because of collisional transfer from C to B. Comparison of the total XeBr and XeI emission intensities with the XeC1 emission intensity from Xe(3P2)+C12 is used to obtain rate constants for XeBr and XeI formation. The branching fractions for XeI and XeBr formation are large, probably unity, for Br2, I2, IC1, and IBr and relatively small for the polyatomic molecules except for CF3I and possible CBr4. From the short wavelength limit of the B–X spectra, upper limits to D0(R–Br) and D0(R–I) are assigned. The theoretical potential curves calculated by Dunning and Hay for the A, B, C, and X states of XeI and XeBr were slightly adjusted so that good agreement was obtained between the simulated and experimental spectra from low vibrational levels of the B and C states. These adjusted potential curves were used to simulate the spectra from high levels of XeBr and XeI, and initial XeBr and XeI vibrational distributions were assigned from matching the low pressure spectra. A systematic decrease in <fV(XeX)≳ is observed in the C12, Br2, I2 series and interpreted as evidence for X(2P1/2) formation. The XeBr and XeI vibrational energy disposal is compared to that from reactions of metal atoms with halogen donors and with reactions of Xe(3P2) with chlorine and fluorine donors.