A Novel, Broadband Spectroscopic Method to Measure the Extinction Coefficient of Aerosols in the Near-Ultraviolet

摘要

Few in situ methods can currently measure the optical properties of aerosols in the near-ultraviolet spectral region. Such measurements are necessary to determine the radiative forcing of different particle types and the subsequent effect on local photochemistry, especially in and around large urban centers. In this work, we demonstrate a system based on incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) to measure the aerosol extinction coefficient with high sensitivity. The system was applied across an atmosphere simulation chamber and had continuous spectral coverage from 320 to 410 nm. Systems studied were ammonium sulfate aerosol and secondary organic aerosol (SOA) formed from the photolysis of 1-nitronaphthalene, an important nitro-polycyclic aromatic hydrocarbon.