The broadband light analyzer of complex aerosol: characterization and first applications

We introduce a new instrument to measure spectral light absorption by aerosol particles. BLAnCA (Broadband Light Analyzer of Complex Aerosol) is an automatic laboratory instrument for offline measurement of aerosol collected on suitable media. BLAnCA is equipped with a white light source and a high-resolution spectrometer, and measures in the range between 375 and 1000 nm with a spectral resolution of 5 nm. This allows for the determination of fine structure of the absorption properties of a sampled aerosol, which can lead to improvement in the robustness and scope of source apportionment and the evaluation of climate-relevant properties such as the aerosol mass absorption cross-section. The new instrument has been validated against a multi-wavelength absorbance analyzer, obtaining an agreement of up to 99 % between absorption coefficient measurements. The absorption coefficient limit of detection for BLAnCA has been estimated at 1.20 Mm⁻¹ (2.70 Mm⁻¹) for standard EU (EPA) sampling conditions, corresponding to an elemental carbon detection limit of about 1.3 $\mu$g cm⁻², if a mass absorption cross-section of $4.7$ m²g⁻¹ at 1000 nm is considered. The instrument has been used to characterize several types of aerosol samples, each with its own distinct absorption features, which show the potential for BLAnCA to identify different kinds of particulate matter based on their optical properties.