Non-projectiveness of X-ray Pendellösung-fringed diffraction images

Area of Science:

• Solid State Physics
• Crystallography
• X-ray Diffraction

Background:

• Standard X-ray dynamical diffraction theory predicts projected fringe patterns.
• Previous experiments indicated X-ray moiré fringes deviate from this projection, showing spatial oscillations.

Purpose of the Study:

• To investigate spatial oscillations in Pendellösung fringes.
• To determine if this non-projective behavior is a general property of X-ray interference fringes.

Main Methods:

• Experimental recording of plane-wave X-ray topographs of a silicon wedge crystal.
• Utilizing multi-stacked films to capture simultaneous topographs.
• Analyzing fringe profiles and topographic images for oscillation patterns.

Main Results:

• Spatial oscillation of Pendellösung fringes was experimentally observed.
• A reciprocal correspondence between fringe oscillation amplitude and fringe contrast was found.
• The observed oscillation confirms non-projectiveness in Pendellösung fringes.

Conclusions:

• Non-projectiveness, evidenced by fringe oscillation, is a fundamental characteristic of X-ray interference fringes in crystal diffraction.
• This finding extends beyond moiré fringes to Pendellösung fringes.
• The results suggest a re-evaluation of standard X-ray dynamical diffraction theory is needed.