Abstract

The extent to which tropospheric aerosols impact the environment, particularly with regard to climate and human health, remains quite uncertain. Given their proximity to Earth's surface, such particles are likely to contain mixtures of organic and inorganic materials. In addition, they are likely to take on different shapes and have different phases. Reducing the uncertainties in the role these particles play requires detailed knowledge of the chemical and physical properties of the materials they are made from. This work focuses on the retrieval of mid-infrared complex refractive indices from the aerosol extinction spectra of commercially available motor oils. There is reason to believe that motor oils could contribute organic material to tropospheric particles, especially in urban areas with high concentrations of internal combustion processes. Refractive index data for these systems can be used in remote sensing applications to measure, amongst other things, composition and particle size. The motor oil results will be compared to refractive indices of long-chain hydrocarbons recently measured in the laboratory. The image shown is a complex refractive index set for a 5W-20 motor oil taken across the mid-infrared.