The Nion HERMES can achieve a 9 meV wide (full-width at half-maximum, FWHM) zero loss peak (ZLP), much smaller than the energy distribution of even the best unmonochromated beam produced by the cold field emission electron gun of a cutting-edge UltraSTEM100 microscope. This makes it possible to not only measure very low energy excitations such as phonons (Krivanek et al. 2014), but also significantly reduces the background resulting from the ‘tail’ of the ZLP at optical and plasmon energies (see Fig. 4/3.1). (Figure courtesy of Tracy Lovejoy / Nion Co.)