Download or read book Optical Properties of Secondary Organic Aerosols written by Hwa Jin Kim and published by . This book was released on 2012 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: The refractive index is the fundamental property controlling aerosol optical properties. Secondary organic aerosols (SOA) constitute a large fraction of aerosols in the atmosphere, and yet the optical properties of this complex material are just beginning to be understood. They appear to be much more variable than expected. We explore the factors controlling the real refractive indices (mr) of SOA under conditions that are as close to atmospheric conditions as possible. SOA were generated from the alpha-pinene, beta-pinene, limonene and toluene using several oxidation chemistries including ozonolysis with and without scavenger and photooxidation at different HC/NOx ratios, different mass concentration and experimental temperatures. Mr were retrieved from polar nephelometer measurements using parallel and perpendicular polarized 532 or 670 nm light where there is no evidence of significant absorption by the particles investigated here. Retrievals were performed with a genetic algorithm method using Mie-Lorenz scattering theory and measured particle size distributions. Overall examination of the SOA data shows that SOA mr ranges from 1.34 to 1.62, reflecting the factors to control the chemical composition; decreases as the HC/NOx ratio increases, decrease at lower temperature (