Efficient Organic Aerosol Formation from Isoprene Photooxidation in Pristine Conditions. JIUMENG LIU, Ben H. Lee, Emma D'Ambro, Felipe Lopez-Hilfiker, Becky Alexander, Rahul Zaveri, Jean C. Rivera-Rios, Frank Keutsch, Siddharth Iyer, Theo Kurten, Ying-Hsuan Lin, Jason Surratt, Pattanun Achakulwisut, Loretta Mickley, Joel A. Thornton, John Shilling, Pacific Northwest National Laboratory