Optical properties of meteoric smoke analogues

Tasha Aylett, James S. A. Brooke, Alexander D. James, Mario Nachbar, Denis Duft, Thomas Leisner, John M. C. Plane
2019 Atmospheric Chemistry and Physics Discussions  
<p><strong>Abstract.</strong> Accurate determination of the optical properties of analogues for meteoric smoke particles (MSPs), which are thought to be composed of iron-rich oxides or silicates, is important for their observation and characterization in the atmosphere. In this study, a photochemical aerosol flow reactor (PAFS) has been used to measure the optical extinction of iron oxide MSP analogues in the wavelength range 325&amp;ndash;675&amp;thinsp;nm. The particles were made
more » ... e made photochemically, and agglomerate into fractal-like particles with sizes on the order of 100&amp;thinsp;nm. Analysis using Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX) and Electron Energy Loss Spectroscopy (EELS) suggested the particles were most likely maghemite-like (<i>&amp;gamma;</i>-Fe<sub>2</sub>O<sub>3</sub>) in composition. The optical extinction coefficients measured using the PAFS were then combined with maghemite absorption coefficients measured using a complementary experimental system, the MICE-TRAPS, to derive complex refractive indices which are able to reproduce both the measured absorption and extinction.</p>
doi:10.5194/acp-2019-240 fatcat:ceada7jnz5h5paf3c5jph2n2ry