Practical Electron Microscopy and Database

The resolution of electron microscopes (EMs) is partially limited by: i) The electrical stability of the EM systems, e.g. the stabilities of the high voltage and the lens currents; ii) External disturbances e.g. mechanical vibration, contamination, charging, fluctuation of stray magnetic fields, and the nonuniform magnetic properties of the pole-piece material used. Furthermore, the fundamental resolution limit of EMs is also described by Scherzer theorem [1], stating that chromatic aberration (C_c) and spherical aberration (C_s) are unavoidable for static, rotationally-symmetric electron lenses. As a result, the resolution of conventional electron microscopes is limited to ~ 100 times the wavelength of the electrons.

[1] O. Scherzer, Z. Phys. 101 (1936) 593.