UV absorption cross sections for SO₃

Room temperature gas phase absorption cross sections for SO 3 have been measured over the wavelength range 195 to 330 nm using a diode array spectrometer. The SO 3 spectrum is continuous with weak diffuse vibrational band structure in the 225 to 295 nm region. Atmospheric photolysis rate calculations show that photolysis of SO 3 in the 190 to 230 nm actinic window is important in determining the sulfur partitioning in the upper stratosphere.