Heterogeneous Chemistry of Nitrogen Oxides and Ozone on the Surface of Soot Agglomerates

INTRODUCTION Recent laboratory studies and model results indicated a possible effect of soot surface reactions on the nitrogen partitioning in the troposphere [Kalberer et al., 1996; Hauglustaine et al., 1997; Rogaski et al., 1997] and on the stratospheric [Lary et al., 1997] and tropospheric ozone concentrations [Bekki et al., 1997]. However, the model predictions are still speculative because the required soot surface reaction probabilities are either unknown or uncertain. Furthermore, most previous laboratory measurements of heterogeneous reaction rates have been carried out on very short time scales using bulk samples and high surface to trace gas concentration ratios compared to atmospheric situations. We report reaction probabilities of ozone and nitrogen oxides on airborne soot particles determined from experiments in our 78 m sized evacuable temperature controlled aerosol chamber AIDA [Bunz et al., 1996] lasting up to several days.