UV-VISIBLE ABSORPTION CROSS-SECTIONS OF BROMINE NITRATE DETERMINED BYPHOTOLYSIS OF BRONO2 BR-2 MIXTURES/

Experiments on the determination of absorption cross sections of bromi ne nitrate by photolysis of BrONO2/Br-2 mixtures were carried out usin g a UV-visible absorption spectrometer. The relatively stable end prod ucts of photolysis were identified as BT2 and N2O5. NO3 was observed a s intermediate product in the photolysis of BrONO2/Br-2 Absorption cro ss sections for BrONO2 at 298 K and 230 K were determined between 208 and 500 nm. The results are in good agreement with a recent independen t study. Calculations of atmospheric photolysis rates of BrONO2 as a f unction of solar zenith angle and surface albedo were undertaken using the PHOTOGT program. The latter are in the range between 0.5x10(-3) s (-1) and 4.0x10(-3) s(-1), indicating that during daylight BrONO2 is r apidly photolyzed.