TEM analysis of volatile nanoparticles from particle trap equipped diesel and direct-injection spark-ignition vehicles

We investigated volatile nanoparticles emitted from two light-duty vehicles using a transmission electron microscope (TEM). Elemental analysis was performed with an energy dispersive system (EDS) attached to the microscope. Differences in stability of volatile nanoparticles during TEM analysis indicated two different chemical compounds. The results are consistent with the thesis that volatile nanoparticles are composed of a more volatile hydrophilic and a less volatile hydrophobic part. Sulfur and potassium were detected in volatile nanoparticles. These elements are likely to play an important role in the formation of volatile nanoparticles. Particle number size distributions derived from a scanning mobility particle sizer (SMPS) and from TEM image analysis were in good agreement.