Silicon nitride transmission X-ray mirrors.

Area of Science:

• Materials Science
• Optics and Photonics
• X-ray Physics

Background:

• Transmission X-ray mirrors are crucial components in synchrotron radiation facilities.
• Existing filters often lack tunability or have limited energy ranges.
• Low-stress silicon nitride offers a promising material for advanced optical components.

Purpose of the Study:

• To fabricate and characterize novel transmission X-ray mirrors using silicon nitride.
• To demonstrate the tunable high-pass energy filtering capability of these mirrors.
• To evaluate the transmittance and angular dependence of the energy cut-off.

Main Methods:

• Fabrication of 300-400 nm-thick low-stress silicon nitride windows (0.6 mm x 85 mm).
• Utilizing the windows as high-pass energy filters at grazing incidence in an X-ray beam.
• Adjusting the incidence angle to select the desired energy cut-off.

Main Results:

• Achieved tunable energy cut-off from 8 to 12 keV by varying the incidence angle.
• Demonstrated a 10 keV cut-off for a 0.22-degree incidence angle with a 0.3 mm x 0.3 mm X-ray beam.
• Observed mirror transmittance exceeding 80% for a 300 nm-thick film.

Conclusions:

• Silicon nitride transmission X-ray mirrors provide a tunable high-pass energy filtering solution.
• The angle-dependent energy cut-off allows for precise X-ray beam conditioning.
• These mirrors offer high transmittance and are suitable for synchrotron applications.