Application of valence electron energy-loss spectroscopy and plasmon energy mapping for determining material...

Measuring material properties at the nanoscale is critical to understanding the behavior of nanostructured materials. In this paper, we demonstrate a novel technique that allows direct determination and imaging of physical properties of individual nanoprecipitates and nanoparticles using energyfiltering transmission electron microscopy combined with valence electron energy-loss spectroscopy (VEELS). We show that strong scaling correlations exist between the plasmon energy and elastic properties, hardness, valence electron density and cohesive energy. We apply these scaling relationships to characterize the elastic properties of metastable nanoprecipitates in a Ti-based structural alloy and the hardness of diesel-engine soot particles. We also discuss additional factors that need to be considered when using plasmons as a quantitative tool for nanoscale property measurement. The results show that VEELS has the potential to determine multiple solid-state properties of materials at the nanoscale, establishing a new capability for analytical electron microscopy.