Meaning
An analytical tool identifies elements and their electronic states by measuring the energy lost by electrons as they pass through a thin slice of material. Information gathered by stem-eels allows researchers to map the distribution of nitrogen or oxygen across a transistor junction at high magnification. The combination of a focused probe and an energy spectrometer provides data that common images alone lack.
It is limited to samples that are thin enough to remain transparent to the electron beam.
Electron Interaction
Particles in the primary beam collide with atoms and transfer specific amounts of energy to their local environment. Analysis via stem-eels counts these energy units to determine which elements are present in the focal spot. The loss patterns also show how the atoms are bonded together.
Spectrum Analysis
Graphics generated during the process display peaks at locations corresponding to specific chemical signatures. Using stem-eels enables the detection of light elements that other tools often overlook. Software subtracts the background noise to highlight shifts in chemical composition across a distance of five nanometers.
Signal Resolution
Capability to distinguish between different oxidation states depends on the precision of the beam focus. Improvements in stem-eels derive from better electron sources and more sensitive cameras at the base of the column. Every scan provides a direct measurement of the sample thickness alongside the chemical data.
