Question

a) A microscope operates at 300keV and has a spherical aberration coefficient of 0.3 mm. Identify the value of the Scherzer focus and the point resolution of the instrument. b) Draw a real space picture of one unit cell of bcc Fe ($a_0 = 2.87$ Å) in the [100] projection. Sketch also the diffraction pattern in this direction and label the innermost spots. Indicate in the real space sketch the lattice planes that correspond to these diffraction spots. c) Which of the diffracted beams, if any, would you be able to image in the bandpass at the Scherzer focus? Would this be adequate to see all the atoms in this projection of the structure? d) If the electron energy spread is 3eV, what would be the largest value of the chromatic aberration coefficient that you could tolerate and still be able to achieve the theoretical resolution?

          a) A microscope operates at 300keV and has a spherical aberration coefficient of 0.3 mm. Identify
the value of the Scherzer focus and the point resolution of the instrument.
b) Draw a real space picture of one unit cell of bcc Fe ($a_0 = 2.87$ Å) in the [100] projection. Sketch
also the diffraction pattern in this direction and label the innermost spots. Indicate in the real
space sketch the lattice planes that correspond to these diffraction spots.
c) Which of the diffracted beams, if any, would you be able to image in the bandpass at the
Scherzer focus? Would this be adequate to see all the atoms in this projection of the structure?
d) If the electron energy spread is 3eV, what would be the largest value of the chromatic
aberration coefficient that you could tolerate and still be able to achieve the theoretical
resolution?

$a) A microscope operates at 300keV and has a spherical aberration coefficient of 0.3 mm. Identify the value of the Scherzer focus and the point resolution of the instrument. b) Draw a real space picture of one unit cell of bcc Fe (a0 = 2.87 Å) in the [100] projection. Sketch also the diffraction pattern in this direction and label the innermost spots. Indicate in the real space sketch the lattice planes that correspond to these diffraction spots. c) Which of the diffracted beams, if any, would you be able to image in the bandpass at the Scherzer focus? Would this be adequate to see all the atoms in this projection of the structure? d) If the electron energy spread is 3eV, what would be the largest value of the chromatic aberration coefficient that you could tolerate and still be able to achieve the theoretical resolution?$

Added by Erin H.

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