Ultraviolet Absorption Spectra and Kinetics of the Self-Reaction of CH2Br and CH2BrO2 Radicals in the Gas Phase at 298 K

Article abstract of DOI:10.1021/j100175a054

The ultraviolet absorption spectra of CH2Br and CH2BrO2 radicals and the kinetics of their self-reactions have been studied in the gas phase at 298 K by using the pulse radiolysis technique.Absorption cross sections were quantified over the wavelength range 220-350 nm.Measured cross sections near the absorption maxima were ?_CH2Br(280 nm) = (6.26 +/- 1.15)*10^-18 cm² molecule^-1 and ?_CH2BrO2(250 nm) = 7.20 +/- 0.83)*10^-18 cm² molecule^-1.Errors represent statistical errors (2?) together with our estimate of potential systematic errors (10percent).The absorption cross-sectional data were then used to derive the observed self-reaction rate constants for reactions 1 and 2 products (1), CH2BrO2 + CH2BrO2 -> products (2)>, defined as -d/dt = 2k_obs² (R = CH2Br or CH2BrO2) of k1= (2.93 +/- 0.60)*10^-11 cm³ molecule^-1 s^-1 and k_obs = (3.26 +/- 0.31)*10^-11 cm³ molecule^-1 s^-1 (quoted errors represent 2?).These results are discussed with respect to previous studies of the absorption spectra and kinetics of peroxy radicals.