Determination of Absolute Structure of Chiral Crystals Using Three-Wave X-ray Diffraction

Abstract

We propose a new method to determine the absolute structure of chiral crystals, which is based on the chiral asymmetry of multiple scattering diffraction. It manifests as a difference in the azimuthal dependence of the forbidden Bragg reflection intensity measured with left and right circularly polarized X-ray beams. Contrary to the existing ones, the suggested method does not use X-ray anomalous dispersion. The difference between the Renninger scans with circularly polarized X-rays has been experimentally demonstrated for the 001 reflection intensities in the right- and left-handed quartz single crystals. A Jmulti-based code on model-independent three-wave-diffraction approach has been developed for quantitative description of our experimental results. The proposed method can be applied to various structures including opaque, organic and monoatomic crystals, even with only light elements. To determine the type of isomer, the Renninger plot of a single forbidden reflection is sufficient.

Introduction to Python Dynamic Diffraction Toolkit (PyDDT): structural refinement of single crystals via X-ray phase measurements

“…As the profile asymmetries are related to the structure factor phases of two or more simultaneously excited hkl reflections, MD experiments have been used as a refinement tool capable of uncovering structural details beyond the resolution limit of other techniques. A list of applications mainly related to phase measurements includes improvement of diffraction anomalous fine structure techniques (Lee et al, 2006;Liu et al, 2016), studies of orbital and charge ordering in magnetic materials (Shen et al, 2006;Weng et al, 2012;Liu et al, 2017), probing minor internal strain induced by ion doping in optical crystals (Morelha ˜o et al, 2011;Amirkhanyan et al, 2014), identification of chirality in crystals with no resonant atoms (Hu ¨mmer & Weckert, 1995;Shen et al, 2000;Morelha ˜o et al, 2015;Kozlovskaya et al, 2021), validation of ionic model structures for amino acid crystals (Morelha ˜o et al, 2017) and inspection of phonon scattering mechanisms in thermoelectric materials (Vale ´rio et al, 2020). This list of successful applications has been possible after decades of knowledge in theoretical approaches and experimental procedures to process MD line-profile asymmetries into structural information (Hart & Lang, 1961;Colella, 1974;Post, 1977;Chapman et al, 1981;Juretschke, 1982;Chang, 1997;Weckert & Hu ¨mmer, 1997;Chang et al, 1999;Wang et al, 2001;Mo et al, 2002;Morelha ˜o & Kycia, 2002;Morelha ˜o, 2003b;Soares et al, 2003;Shen, 2003;Thorkildsen et al, 2003).…”