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FIB-SEM tomography and its application towards understanding aerosol optical properties of atmospheric dust particles

Published

Author(s)

Diana Ortiz-Montalvo, Robert D. Willis, Joseph M. Conny

Abstract

Atmospheric dust particles have complex morphologies as observed in scanning electron microscopy (SEM) images. Yet, despite their non-spherical shape and the growing evidence of shape-related uncertainty, these particles are commonly treated as spheres or spheroids in aerosol radiative forcing models and aerosol optical remote sensing applications. Dust particles are known to have a strong influence on Earth's radiative balance. However, the extent to which they cool or warm the Earth's atmosphere remains largely uncertain. Aerosol optical properties influence such cooling or warming behavior to a large extent, which depends on particle morphology, composition, size, and other factors. Our work aims to improve current understanding of aerosol optical properties by using high-resolution information on the shapes, volumes and surface roughness of ambient dust particles as obtained from focused ion-beam (FIB) SEM tomography, as well as elemental composition from energy- dispersive x-ray spectroscopy (EDS). Overall, our studies using FIB-SEM tomography and optical property modeling have shown that the shape of a particle plays a vital role in its light-scattering properties and that using spherical or spheroidal shape models can generate large deviations in those properties. Furthermore, that optical property estimates from tetrahedral shapes had better agreement with the actual particle shape, when compared to spherical and cubic shapes. Based on our findings we recommend the use of tetrahedral shape models in remote sensing applications and radiative forcing calculations to best represent the shape irregularity and surface roughness of ambient dust particles.
Proceedings Title
Microscopy & Microanalysis 2020
Conference Dates
August 2-6, 2020
Conference Location
Milwaukee, WI, US

Keywords

atmospheric aerosol, dust particles, scattering, extinction, backscatter fraction, particle shape, surface roughness, scanning electron microscopy, focused ion-beam tomography, FIB-SEM, discrete dipole approximation

Citation

Ortiz-Montalvo, D. , Willis, R. and Conny, J. (2020), FIB-SEM tomography and its application towards understanding aerosol optical properties of atmospheric dust particles, Microscopy & Microanalysis 2020, Milwaukee, WI, US (Accessed March 2, 2024)
Created July 30, 2020, Updated March 8, 2023