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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Furthermore, X-ray emission also depends on the energy of incident beam. For incident electrons at low energies, it is very important to know that a useful X-ray signal can only be generated with a beam energy which is at least 1.3 x the ionization energy for the relevant characteristic X-rays. X-ray yields, in this condition, are also relative low and depend strongly on overvoltage  (U<3) and the X-ray signals are relatively weak.