X-ray Crystallography Overview

Principles

Definition

X-ray crystallography is a scientific technique that employs the diffraction of X-rays by the periodic arrangement of atoms in a crystalline solid to determine its atomic and molecular structure, which is fundamental for understanding the properties and functions of materials and biological molecules.

Ontological type

Experimental Methods

Chemical Applications

Core Principles

Key developments

Key Figures

Quantitative Diffraction Metrology era

A. J. C. Wilson [1] was a prominent figure in the Quantitative Diffraction Metrology era, with affiliations at the Massachusetts Institute of Technology [3] and the Georgia Institute of Technology [4]. His contribution is exemplified by The diffraction of X rays by distorted crystal aggregates - I [7] (1944), which advanced quantitative treatment of X-ray diffraction from distorted crystal aggregates and informed lattice-constant determination and phase analysis in this era. G. W. Brindley [2] was likewise active in the era, with affiliations at Park University [5] and Pennsylvania State University [6]. Brindley's key contribution, The measurement in absolute units of the intensities of X-ray reflections from crystalline powders [8] (1938), established absolute intensity scales for powders, enabling standardized comparisons and underpinning rigorous metrology and subsequent quantitative refinement in this period.

Dynamical and Electronic Integration era

George M. Sheldrick [1] was active at institutions such as the University of Cambridge [3] and the University of Iowa [4] during this era. His key contribution in this era was the phase annealing approach described in Phase annealing in SHELX-90: direct methods for larger structures [7], which broadened the applicability of direct methods to larger structures and improved convergence in complex datasets. James A. Ibers [2] held appointments at Harvard University [5] and the Massachusetts Institute of Technology [6] during this era. His notable contribution from this era is the International Tables for X-ray Crystallography [8], published in 1976, which provided foundational reference data and standardization for crystallographic calculations, enabling more accurate interpretation of scattering experiments.

Automated Serial Crystallography era

George M. Sheldrick [1] is associated with Washington University in St. Louis [3] and Seoul National University [4], and has shaped crystallographic practice in the Automated Serial Crystallography era (1993–2024). His key contributions include the development of robust refinement workflows exemplified by Crystal structure refinement with SHELX [7], which enabled automated model refinement and reliable structure verification essential for high-throughput pipelines. Jane S. Richardson [2], with affiliations at Duke University [5] and the University of North Carolina at Chapel Hill [6], helped lay the groundwork for automated macromolecular structure solution and validation in this era. Her contributions are exemplified by PHENIX [8], a comprehensive Python-based system for macromolecular structure solution, and MolProbity [9], all-atom structure validation, which together powered automated end-to-end validation and quality assurance in serial crystallography.