Nanoparticles are often overlooked during routine trace evidence analyses because of their small size and the degree of
difficulty needed to efficiently characterize them. However, analytical electron microscopy (AEM) enables the
characterization and/or identification of nanoparticles because of its high magnification capability, the ability to gather
elemental data and also the ability to determine the internal structure of a single nanoparticles(1). There is a wide variety
of natural and manufactured nanoparticles that are prominent within the environment and their presence becomes very
valuable in the absence of larger particles. The combustion of materials produces by-products such as nano-sized carbon
soot, fumes, fly ash and gun-shot residue (GSR). Using AEM, nano-sized carbon soot, fumes, fly ash and GSR can not
only be distinguished from other nanoparticles within the environment but can also be distinguished from each other
because of differences in morphology, elemental composition, and internal structure. The elemental information
gathered from combustion by-products during AEM analysis can also give an indication of the original source material.
Other nanoparticles such as paint pigments and fillers can also be characterized by AEM using morphology, electron
diffraction and elemental composition.