A DISCHARGE-FLOW PHOTOIONIZATION MASS-SPECTROMETRIC STUDY OF THE BRO (X2-PI) RADICAL - PHOTOIONIZATION SPECTRUM AND IONIZATION-ENERGY

The photoionization spectrum of BrO was measured over the wavelength r ange lambda = 106-122 nm using a discharge-flow photoionization mass s pectrometer apparatus coupled to a synchrotron radiation source. BrO w as generated by the reaction of O(3P) atoms with molecular bromine. A value of 10.46 +/- 0.02 eV was obtained for the adiabatic ionization e nergy of BrO from photoion thresholds, corresponding to the BrO+ (X 3S IGMA-)<--BrO(X 2PI3/2) transition. Spectra for both the (BrO)-Br-79 an d (BrO)-Br-81 isotopes were very similar and the resultant photoion th resholds were identical, within experimental uncertainty. The structur e observed in the spectra is discussed in terms of available states fo r BrO+, which have been calculated using MC-SCF methods.