This experimental investigation addresses atmospheric bromine chemistry. Bromine dioxide, OBrO, has recently been reported to be present in the atmosphere as a principal night-time bromine species, implying a potentially important role for OBrO chemistry at night time. The chemical fate and atmospheric role of the OBrO radical have not been determined. Preliminary model simulations indicate that the homogeneous reactions of OBrO with ozone, nitric oxide, and chlorine monoxide affect the stratospheric ozone budget and bromine species partitioning, particularly in the lower stratosphere where ozone concentrations are greatest. It is possible that OBrO strongly interacts with polar stratospheric clouds (PSCs). Kinetic rate parameters for the interactions between OBrO and O3, NO, ClO and water-ice will be measured under stratospheric conditions using a fast flow reactor coupled with mass spectrometry. Preliminary laboratory results indicate that OBrO is several times more reactive than OClO towards NO at room temperature.
