An X-ray Raman spectrometer for EXAFS studies on minerals: bent Laue spectrometer with 20 keV X-rays

Area of Science:

• Materials Science
• Geochemistry
• Spectroscopy

Background:

• Traditional X-ray Raman spectrometers use lower energy X-rays (≤10 keV), limiting sample penetration depth and signal intensity.
• Studies of local structures in minerals require high-resolution spectroscopic techniques.

Purpose of the Study:

• To develop and present a novel X-ray Raman spectrometer utilizing ~20 keV X-rays and a bent Laue analyzer.
• To enhance the scattering volume and integrated intensity for improved mineral structure analysis.

Main Methods:

• Utilized ~20 keV X-rays for increased sample penetration.
• Employed a bent Laue analyzer for wide band-pass and high reflectivity.
• Measured oxygen K-edge in SiO(2) glass and α-quartz using EXAFS and XANES modes.

Main Results:

• Achieved energy resolutions of 4 eV (EXAFS mode) and 1.3 eV (XANES mode).
• Demonstrated enhanced integrated intensity due to increased scattering volume and analyzer performance.
• Successfully reproduced EXAFS features using a cluster model with minimal fitting parameters.

Conclusions:

• The proposed X-ray Raman spectrometer offers superior performance for studying local mineral structures.
• The developed data processing methods, including theoretical Compton profiles and Monte Carlo simulations, aid in EXAFS analysis.
• The spectrometer and techniques are suitable for high-pressure mineral studies.