Extracting physically interpretable data from electron energy-loss spectra

Principal component analysis is routinely applied to analyze data sets in electron energy-loss spectroscopy (EELS). We show how physically meaningful spectra can be obtained from the principal components using a knowledge of the scattering of the probe electron and the geometry of the experiment. This approach is illustrated by application to EELS data for the carbon K edge in graphite obtained using a conventional transmission electron microscope. The effect of scattering of the probe electron is accounted for, yielding spectra which are equivalent to experiments using linearly polarized X-rays. The approach is general and can also be applied to EELS in the context of scanning transmission electron microscopy.