A DISCHARGE FLOW-PHOTOIONIZATION MASS-SPECTROMETRIC STUDY OF HOBR(X (1)A') - PHOTOION YIELD SPECTRUM, IONIZATION-ENERGY, AND THERMOCHEMISTRY

The photoion yield spectrum of HOBr was measured over the wavelength r ange lambda= 108-121 nm; by using a discharge flow-photoionization mas s spectrometer apparatus coupled to a synchrotron radiation source. HO Br was generated by the reaction of OH with molecular bromine. A value of(10.62+/-0.04) eV was obtained for the adiabatic ionization energy (I.E.) of HOBr from photoion thresholds, corresponding to the HOBr+((2 )A'') <--HOBr((1)A') transition. The structure observed in the spectru m is discussed in terms of the available states for HOBr+, which have been determined using multiconfiguration-self-consistent field calcula tions. A new value for Delta H-f(0) (298)(HOBr) of-9 kcal mel(-1) is d erived from I.E.(HOBr) and estimates of Delta H-f(HOBr+).