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In EMs, the resolution limit due to chromatic aberration can be estimated by,
 [4241]
where,
C_{c}  Chromatic aberration coefficients
λ  Electron wavelength
ΔE/E  Relative energy width of the electron beam
We can see that Equation 4241 is related to a beam broadening factor due to chromatic aberration (C_{c}) of the objective lens because of the finite width of the energyselecting slit.
Example of estimated resolution limits are shown in Figure 4241. At high accelerating voltages (e.g. 200 kV) the spherical aberration is dominant, while at low accelerating voltages (e.g. 1 kV) the chromatic aberration is dominant. Generally speaking, spherical aberration is the dominant resolutionlimiting aberration at accelerating voltages larger than about 100 kV.
Figure 4241. The estimated resolution limits at 1 kV and 200 kV as function of C_{s} and C_{c}assuming only one of them is present in each case. The energy width of the beam was assumed to be 0.7 eV.
