This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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Corrections of spherical aberration and off-axial coma have been recently used for improving the spatial resolution of TEM imaging. However, these corrections cannot further improve the resolution when reaching 0.5 Å at voltages ≤ 200 kV due to chromatic aberration. Fortunately, the chromatic aberration can decrease significantly by employing a monochromator or be corrected by crossed electric and magnetic quadrupole elements. In these setups, their electric and magnetic forces compensate each other for the electrons with nominal energies. Up to now, the use of a monochromator and a hexapole aplanator is most promising and holds the chromatic aberration to a minimum and within acceptable limits.