Characterization of Ambient Airborne Particles by Energy-Filtered Transmission Electron Microscopy

Abstract

This article demonstrates that energy-filtered trairsmission electron microscop, (EFTEM) can be a valuable tool for the identification and analysis of nanometer-sized airborne particles. Ambient airborne particulate matter (PM) samples collected at Lexington, Kentucky were investigated using EFTEEM in combination with electron energy-loss spectroscopy (EELS), energg-dispersive Xray spectroscopy (EDS), selected area electron diffraction(SAED), and high-resolution transmission electron microscopy (HARTEM). EFTEM provides a fast and convenient way to map the distribution of carbonaceous aggregates, which cnstitute a significant fraction of the samples. Sulfur-bearing particles are common in the submicron inorganic fraction. Sulfur elemental maps were obtained from some sulfur-beariang particles, and the oxidation state of sulfur was revealed to be primarily S(VI) as sulfate from the electron energy-loss near-edge fine structures of the sulfur L-edge. Other types of inorganic particles, such as silicon-bearin...