Electron microscopy
 
TEM/STEM Characteristics Affected by CTF Damping
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For the coherent scattering in TEM imaging mode, the coherent contribution of different CTFs can cause a loss of amplitude at high Δk due to the CTF oscillation in sign. Such instability results in differences in phase at large Δk for individual incident electrons. Note that most of the CTF damping is caused by the fluctuations of the lens currents or the high voltage of the microscope.

For the incoherent scattering in HAADF imaging mode, each electron has an positive intensity so that the wave destruction effect does not exist. For such scattering, the important parameter is the distribution of the incident electrons in the probe beam.

Therefore, the information limit for HRTEM imaging is smaller than for coherent HAADF-STEM imaging.

 

 

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