EELS IN THE TEM - NANOMETER RESOLUTION WITHOUT A NANOPROBE

With many TEMs, the resolution of electron energy loss spectrometry (E ELS) is limited to similar to 100 nm since a finer probe cannot be pos itioned and maintained accurately enough for the long dwell times nece ssary. The alternative TEM image mode (i. e. projecting the area of in terest onto the spectrometer aperture) suffers from the energy depende nt chromatic blurring, limiting the resolution also to several 100 nm. Due to inevitable misalignment of post specimen lenses (PSLs), electr ons that have suffered a characteristic loss will hit the screen at a different position than the elastically scattered ones, even when the chromatic blurring is compensated by objective lens defocus. We descri be a correction method for both the chromatic blurring and the chromat ic image shift. It is shown by example that quantitative EELS analysis can be done on a scale of better than 10 nm with spots of arbitrary s ize in regular TEM image-mode.