Heterogeneous processes are known to play important roles in the chemistry of stratospheric ozone. In constructing models of heterogeneous reactions occuring in the stratosphere, a complete data set for the involved physico-chemical processes in the gas and particle phases is required.

We have improved a recently developed capillary column method to measure diffusion coefficients and solubilities of trace gases in thin film sulfuric acid solutions (film thickness between 1 and 2 mym, 40 to 80 wt% sulfuric acid) at stratospheric temperatures down to -90 C. The trace gases are detected using a novel ion trap mass spectrometer. The experimental approach is described on the poster and first results are discussed.