The principle of a double crystal electron interferometer

Area of Science:

• Condensed Matter Physics
• Crystallography
• Electron Microscopy

Background:

• Sinusoidal interference fringes have been observed using double crystal interferometers and convergent beam electron diffraction.
• The precise formation mechanism of these interference fringes remains incompletely understood.

Purpose of the Study:

• To elucidate the formation mechanism of sinusoidal interference fringes in a double crystal interferometer.
• To analyze the necessary coherence conditions for this specialized interferometer.
• To explore the potential applications of this interference phenomenon in electron diffraction.

Main Methods:

• Application of wave theory to explain the observed interference fringes.
• Analysis of excitation errors of partial exit waves from the crystal wave splitter.
• Comparison of interference effects in real space versus reciprocal space (Fourier space).

Main Results:

• Excitation errors of partial exit waves are identified as the cause of interference fringe formation.
• A novel interference mechanism is demonstrated in reciprocal space using the double crystal interferometer.
• The interferometer operates without rigorous coherence conditions.

Conclusions:

• The study provides a theoretical explanation for sinusoidal interference fringes in double crystal interferometry.
• The observed reciprocal space interference offers potential for Fraunhofer plane holography.
• This technique may allow measurement of reflection phase and amplitude, yielding atomic position and unit cell symmetry information.