A liquid jet of 90 ~tm diameter and variable length has been utilized to determine absorption rates and, hence, mass accommodation coefficients y, of atmospheric trace gases. The compounds investigated are HC1 (~,~>0.01), HNO 3 (y~>0.01), N205 (~,>~0.005), peroxyacetyl nitrate (y > 0.001), and HONO (~, >/0.005). It is concluded that the absorption of these trace gases by liquid atmospheric water is not significantly retarded by interfacial mass transport. The strengths and limitations of the liquid jet technique for measuring mass accommodation coefficients are explored.

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Gas-phase diffusion is the first step for all heterogeneous reactions under atmospheric conditions. Knowledge of binary diffusion coefficients is important for the interpretation of laboratory studies regarding heterogeneous trace gas uptake and reactions. Only for stable, nonreactive and nonpolar gases do well-established models for the estimation of diffusion coefficients from viscosity data exist. Therefore, we have used two complementary methods for the measurement of binary diffusion coefficients in the temperature range of 200 to 300 K: the arrested flow method is best suited for unstable gases, and the twin tube method is best suited for stable but adsorbing trace gases. Both methods were validated by the measurement of the diffusion coefficients of methane and ethane in helium and air as well as nitric oxide in helium. Using the arrested flow method the diffusion coefficients of ozone in air, dinitrogen pentoxide and chlorine nitrate in helium, and nitrogen were measured. The twin tube method was used for the measurement of the diffusion coefficient of nitrogen dioxide and dinitrogen tetroxide in helium and nitrogen.

<p><strong>Abstract.</strong> Gas phase diffusion is the first step for all heterogeneous reactions under atmospheric conditions. Knowledge of binary diffusion coefficients is important for the interpretation of laboratory studies regarding heterogeneous trace gas uptake and reactions. Only for stable, nonreactive and non polar gases well-established models for the estimation of diffusion coefficients from viscosity data do exist. Therefore, we have used two complementary methods for the measurement of binary diffusion coefficients in the temperature range of 200 K to 300 K: the arrested flow method is best suited for unstable gases and the twin tube method is best suited for stable but adsorbing trace gases. Both methods were validated by measurement of diffusion coefficients of methane and ethane in helium and air and nitric oxide in helium. Using the arrested flow method the diffusion coefficients of ozone in air, dinitrogen pentoxide and chlorine nitrate in helium and nitrogen were measured. The twin tube method was used for the measurement of the diffusion coefficient of nitrogen dioxide and dinitrogen tetroxide in helium and nitrogen.</p>