X-ray triple refraction and triple absorption in a cobalt-complex crystal

Area of Science:

• Solid-state physics
• Crystallography
• X-ray optics

Background:

• X-ray optical properties of anisotropic crystals are crucial for understanding material behavior.
• Previous studies have not quantitatively measured X-ray triple refraction and absorption in monoclinic crystals.

Purpose of the Study:

• To quantitatively measure X-ray triple refraction and triple absorption in different crystallographic orientations of a cobalt-complex monoclinic crystal.
• To investigate the X-ray optical anisotropy of biaxial crystals.

Main Methods:

• Utilized an energy-tunable X-ray polarimeter with a phase retarder.
• Scanned X-ray energy across the cobalt K-absorption edge.
• Measured X-ray polarization ellipticity and rotation spectra for (100)-, (010)-, and (001)-oriented crystal plates.

Main Results:

• Demonstrated distinct X-ray polarization spectra for each crystal orientation, confirming anisotropy.
• Quantitatively determined three unique refractive indices and absorption coefficients for the monoclinic crystal in the X-ray region.
• Verified the Kramers-Kronig relation for dielectric anisotropy across all orientations.

Conclusions:

• X-ray triple refraction and absorption are significant in monoclinic crystals.
• The study provides the first quantitative measurement of these properties, revealing biaxial behavior.
• Confirms the applicability of Kramers-Kronig relations to X-ray dielectric anisotropy.