I have seen the "universal" curve of inelastic mean free path (MFP) of electrons in many places (both experimental data, and just sketches of the curve) e.g. https://en.wikipedia.org/wiki/Inelastic_mean_free_path
- Why does the MFP rise at low energy? I think this is because there are no scattering mechanisms at low energy - but don't have any good details or resources to back up that claim.
- If the MFP is very large at low energy, then why do TEM's require large energies for imaging? Perhaps it is the technical trouble of being able to detect ~1-10 eV electrons above the noise level (?)