MODELLING OF RAMAN SCATTERING ON PHOTOSYNTHETICAL ACTIVE AEROSOL DROPLETS M.V. JOURAVLEV 1 and G. KURIZKI 2 . 1 Aerosol Department of SSC of Russian Federation, Karpov Institute of Physical Chemistry, 103064, Moscow, Vorontsovo pole 10, Russia. 2 Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot, Israel. Keywords: DROPLETS, PHOTOSYNTHESIS, CO2 DIFFUSION INTRODUCTION Photochemical reactions in aerosol droplets containing photosynthetic bacteria or single chloroplast have applications for atmospheric microbiology and biochemistry of the global problem of CO2 exchange. The photosynthetic reaction in aerosol droplets creates time dependent radial O2 and CO2 distributions these droplets. The suspended micrometer spherical aerosol droplets behave as optical resonators in which light is concentrated in small part of inclusions. The electromagnetic field of such system has nonuniform distribution in the volume, so that the photosynthetic processes and gas exchange in aerosol droplets with inclusions differ from the well known leaf photosynthesis. Our work is aimed at adapting the methods based on stimulated Raman scattering for mathematical modeling and measurement of CO2 uptake and CO2 concentration in photosynthetic active aerosol droplets as well as the corresponding reaction constant. METHODS AND THEORY The suitable models of light driven chemical reactions were developed by (Kaitala, 1982; Hari et al., 2000).The structure of the model is shown in Fig.1. Large spherical aerosol droplets with spherical inclusions of photosynthetic bacteria or chloroplast are considered. A simplified version of carbon reduction cycle takes into account CO2 diffusion. Photosynthetic carbon metabolism is simplified drastically, so that only the turnover of carbon and interconversion of Calvin cycle, of ATP (S*-compound) and ADP (S- compound) are considered. The pools of intermediate Calvin cycle are lumped, and only two species RuBP (X-compound) and PGA (Y-compound) are assumed to exist. Fig.1 The model of the light driven chemical reaction. hν S* S X Y CO2 Abstracts of the European Aerosol Conference 2004 S933