Reactive uptake coefficients for heterogeneous reaction

Introduction Conclusions References Tables Figures Back Close Abstract Introduction Conclusions References Tables Figures Back Close Abstract The kinetics of uptake of gaseous N 2 O 5 on submicron aerosols containing NaCl and natural sea salt has been investigated in a flow reactor as a function of relative humidity (RH) in the range 30–80% at 295±2 K and a total pressure of 1 bar. The measured uptake coefficients, γ, were larger on the aerosols containing sea salt compared to those 5 of pure NaCl, and in both cases increased with increasing RH. These observations are explained in terms of the variation in water content and hence size of the salt droplets, which leads to a limitation in the uptake rate into small particles. After correction for this effect the uptake coefficients are independent of relative humidity, and agree with those measured previously on larger droplets. A value of γ=0.025 is recommended for 10 the reactive uptake coefficient for N 2 O 5 on deliquesced sea salt droplets at 298 K and RH >40%.