Development of new apertures for coherent X-ray experiments

Area of Science:

• Physics
• Materials Science
• Optics

Background:

• Coherent small-angle X-ray scattering (CSAXS) experiments require precise spatial filtering of the X-ray beam.
• Fraunhofer diffraction from beam-defining slits is a significant source of background noise in CSAXS.
• Standard slits lead to a background intensity that scales inversely with the square of the wavevector.

Purpose of the Study:

• To design and test novel X-ray slits that minimize parasitic background in CSAXS.
• To develop a theoretical model predicting the diffraction pattern characteristics of the new slit design.
• To experimentally validate the theoretical model using X-ray diffraction measurements.

Main Methods:

• Design of new X-ray slits featuring partially transmitting, inclined slit jaws for beam apodization.
• Development of a theoretical model to predict Fraunhofer diffraction patterns from the novel slits.
• Experimental measurement of Fraunhofer diffraction patterns using 3 and 5.5 keV X-rays with GaAs single-crystal edges.

Main Results:

• The new slit design effectively minimizes parasitic background.
• The theoretical model accurately predicts that the diffraction pattern tails scale with the inverse fourth power of the wavevector.
• A novel phase-peak diffraction pattern, linked to transmitted electric field phase variations, was observed and explained by the model.

Conclusions:

• The developed slit design offers a significant reduction in background noise for CSAXS.
• The theoretical model provides accurate predictions for diffraction patterns, including novel phase phenomena.
• These advancements enhance the precision and reliability of coherent X-ray scattering techniques.