Correlations between optical, chemical and physical properties of biomass burn aerosols

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Abstract

[1] Aerosols generated from burning different plant fuels were characterized to determine relationships between chemical, optical and physical properties. Single scattering albedo (ω) and Angstrom absorption coefficients (αap) were measured using a photoacoustic technique combined with a reciprocal nephelometer. Carbon-to-oxygen atomic ratios, sp2 hybridization, elemental composition and morphology of individual particles were measured using scanning transmission X-ray microscopy coupled with near-edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS) and scanning electron microscopy with energy dispersion of X-rays (SEM/EDX). Particles were grouped into three categories based on sp2 hybridization and chemical composition. Measured ω (0.4 − 1.0 at 405 nm) and αap (1.0 − 3.5) values displayed a fuel dependence. The category with sp2 hybridization >80% had values of ω (<0.5) and αap (∼1.25) characteristic of light absorbing soot. Other categories with lower sp2 hybridization (20 to 60%) exhibited higher ω (>0.8) and αap (1.0 to 3.5) values, indicating increased absorption spectral selectivity.

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