Journal of Analytical & Bioanalytical Techniques
Open Access

The experimental science of determining the arrangement of atoms in crystalline substances is known as crystallography. The study of crystals was relied on physical measurements of their geometry using a goniometer before the discovery of X-ray diffraction crystallography. The study of crystals was relied on physical measurements of their geometry using a goniometer before the introduction of X-ray diffraction crystallography. This entailed determining the symmetry of the crystal in issue by measuring the angles of crystallographic structure related to one another and to theoretical reference axes (crystallographic axes). A stereographic net, such as a Wulff net or Lambert net, is used to trace the position of each crystal face in 3D space.

Crystallographic techniques now rely on analysing the diffraction patterns of a sample that has been hit by a beam of some sort. The most common beams utilised are X-rays, however electrons and neutrons can also be employed. X-ray crystallography, neutron diffraction, and electron diffraction are all terminology used by crystallographers to specify the type of beam utilised. Obtaining an image of a small item using traditional imaging techniques such as optical microscopy necessitates collecting light with a magnifying lens. The diffraction-limit of light, which is dependent on wavelength, limits the resolution of any optical system. As a result, the overall clarity of the resulting crystallographic electron density maps is significantly influenced by the diffraction data resolution, which can be classified as low, medium, high, or atomic. The existing structure of atoms in a crystal cannot be resolved with a typical optical microscope. Radiation with substantially shorter wavelengths, such as X-ray or neutron beams, would be required.

Some crystallographically studied materials, such as proteins, do not form naturally as crystals. Generally, such molecules are dissolved in water and allowed to crystallise slowly through vapour diffusion. In a container having a reservoir containing a hygroscopic solution, a drop of solution comprising the molecule, buffer, and precipitants is sealed. After obtaining a crystal, data can be gathered using a radiation beam. Although many colleges with crystallographic research have their own X-ray producing equipment, synchrotrons are frequently used as X-ray sources because they produce purer and more comprehensive patterns. Because synchrotron sources have substantially stronger X-ray beams, data collection takes a fraction of the time it takes at weaker sources.

The mathematical methods for analysing diffraction data are limited to patterns, which are only produced when waves diffract from orderly arrays. As a result, crystallography is mostly limited to crystals or molecules that may be persuaded to crystallise for measuring purposes. Despite this, patterns created by fibres and powders, while not as flawless as a solid crystal, can demonstrate some order, can be used to extract chemical information.

Materials scientists utilise crystallography to characterise various materials. Because the inherent morphologies of crystals reflect the atomic structure, the impacts of the crystalline arrangement of atoms are typically simple to perceive macroscopically in single crystals. Furthermore, crystalline imperfections frequently regulate physical qualities. Understanding crystal structures is a necessary precondition for comprehending crystallographic faults. Crystallography is also linked to other physical qualities. Clay minerals, for example, produce small, flat, plate like formations. Clay is easily deformed because plate like particles can slide along one other in the plane of the plates while remaining tightly linked in the perpendicular direction. Crystallographic texture measurements can be used to investigate such systems.

When it comes to phase identification, crystallography comes in handy. It is often desirable to know what compounds and phases are present in a material before making or using it, as their composition, structure, and proportions will influence the material's qualities. The atoms in each phase are arranged in a specific pattern. X-ray or neutron diffraction can be used to determine which patterns, and consequently which compounds, are present in a material. The principal approach for determining the molecular conformations of biological macromolecules, particularly protein and nucleic acids like DNA and RNA, is X-ray crystallography. In reality, crystallographic data was used to derive DNA's double-helical structure.