X-ray diffraction and spectroscopy

Anomalous diffraction

Anomalous diffraction is the resonant contribution to x-ray diffraction when the x-ray energy approaches an atom's absorption edge, exploited by MAD and SAD methods to solve the crystallographic phase problem.

Crystal diffraction

Crystal diffraction is a structural characterization method that determines the atomic arrangement of crystalline materials from diffraction patterns produced when X-rays, electrons, or neutrons scatter from the crystal lattice.

Direct methods (crystallography)

Direct methods are crystallographic techniques that estimate missing diffraction phases from intensities alone, developed by Karle and Hauptman, who won the 1985 Nobel Prize in Chemistry.

Distorted-wave Born approximation

The distorted-wave Born approximation (DWBA) is a perturbative method in scattering theory treating strong refraction and reflection exactly, developed by George Vineyard in 1982 for grazing-incidence X-ray and neutron scattering.

Double-crystal monochromator

A double-crystal monochromator is an X-ray optical device in which two crystals diffract a beam twice to select a narrow, tunable energy band, standard at hard X-ray synchrotron beamlines.

Energy-dispersive X-ray diffraction

Energy-dispersive X-ray diffraction, also called white-beam XRD, is a technique in which a polychromatic X-ray beam and energy-discriminating detector record diffraction patterns at a fixed angle, suited to time-resolved and bulk studies.

Energy-dispersive X-ray fluorescence

Energy-dispersive X-ray fluorescence (EDXRF) is an elemental analysis technique that excites a sample with X rays and identifies its elements from their emitted X-ray energies.

Extended X-ray absorption fine structure spectroscopy

Extended X-ray absorption fine structure (EXAFS) spectroscopy is an element-specific X-ray technique that determines which neighbors surround an element, at what distances and numbers, probing local structure within about 5 Å without requiring long-range crystalline order.

Femtosecond crystallography

Femtosecond crystallography, practiced as serial femtosecond crystallography (SFX), determines atomic structures of protein microcrystals from femtosecond X-ray free-electron laser snapshots, merging thousands of still images taken before each crystal is destroyed.

Fluctuation X-ray scattering

Fluctuation X-ray scattering (FXS), also called correlated X-ray scattering, is an X-ray technique proposed by Zvi Kam in 1977 that recovers particle structure from angular correlations in diffraction patterns.

Four-circle diffractometry

Four-circle diffractometry is a single-crystal diffraction technique in which a crystal is rotated on a goniometer with four circles, three Eulerian angles and the detector angle, to measure each reflection's intensity.

Grazing-incidence small-angle X-ray scattering

Grazing-incidence small-angle X-ray scattering (GISAXS) is a surface-sensitive X-ray technique, essentially reflection-mode SAXS, that reveals nanoscale structure in thin films and on surfaces at grazing incidence angles below 2°.

Grazing-incidence wide-angle X-ray scattering

Grazing-incidence wide-angle X-ray scattering (GIWAXS) is an X-ray method in which a beam strikes a flat sample below 1° to determine thin-film crystal structure and orientation.

Grazing-incidence X-ray diffraction

Grazing-incidence X-ray diffraction (GIXD), also called GIWAXS, is an X-ray diffraction technique in which the beam strikes below one degree, revealing crystal structure in nanometer-thin films.

High-energy-resolution fluorescence detection

High-energy-resolution fluorescence detection (HERFD) is a detection mode for X-ray absorption spectroscopy in which emitted fluorescence is analyzed with a crystal spectrometer, reducing core-hole lifetime broadening.

High-pressure X-ray diffraction

High-pressure X-ray diffraction is the measurement of X-ray diffraction patterns from crystalline samples under elevated pressure, usually in a diamond anvil cell, to determine structure, equation of state, and phase transitions.

High-resolution X-ray diffraction of epitaxial layers

High-resolution X-ray diffraction (HRXRD) is a branch of X-ray diffraction that uses highly monochromatic beams to measure composition, thickness, strain, relaxation, and defect broadening in single-crystalline epitaxial layers, an essential semiconductor characterization tool.

International Centre for Diffraction Data

The International Centre for Diffraction Data (ICDD), founded in 1941 and based in Newtown Square, Pennsylvania, is a non-profit organization publishing the Powder Diffraction File database of powder diffraction data.

Micro-X-ray fluorescence

Micro-X-ray fluorescence (micro-XRF, μ-XRF) is an analytical technique that maps elemental composition at micrometer scale with a focused X-ray beam, non-destructively, used in cultural heritage, geology, and biology.

Nanofocused X-ray diffraction

Nanofocused X-ray diffraction is a synchrotron-based characterization method in which a hard X-ray beam focused to tens of nanometers maps strain, defects, lattice orientation, and phase in materials.

Orientation distribution function

The orientation distribution function (ODF) is a probability density describing how crystallites in a polycrystalline material are oriented, the central quantity of texture analysis, typically recovered from diffraction pole figures.

Patterson method

The Patterson method is a crystallographic technique introduced by Arthur Lindo Patterson in 1934 that derives structural information from X-ray diffraction data without requiring lost phase information.

Portable X-ray fluorescence

Portable X-ray fluorescence (pXRF), also called hand-held XRF, is a non-destructive method in which a compact instrument directs X-rays at a sample to measure elemental concentrations on the spot, used in soil screening, mining, and archaeology.

Reciprocal space mapping

Reciprocal space mapping (RSM) is a high-resolution X-ray diffraction technique that maps intensity over an area of reciprocal space, revealing lattice parameters, strain, and mosaicity in crystals and epitaxial films.

Resonant photoemission

Resonant photoemission is a photoelectron spectroscopy variant in which the photon energy is tuned to a core-level absorption threshold, enhancing valence-band emission through an interfering indirect decay channel and making the technique element selective.

Terahertz pump–X-ray probe

Terahertz pump–X-ray probe is an ultrafast pump–probe technique in which an intense terahertz pulse excites a sample and a delayed ultrashort X-ray pulse records the resulting structural or electronic response.

TES X-ray microcalorimeter spectrometry

TES X-ray microcalorimeter spectrometry is an energy-dispersive X-ray detection technique in which a superconducting transition-edge sensor reads each photon's energy as heat, achieving resolutions of 1–10 eV.

Time-resolved X-ray absorption spectroscopy

Time-resolved X-ray absorption spectroscopy (TR-XAS) is a pump–probe technique tracking oxidation state, spin state, and local geometry on femtosecond-to-millisecond timescales, first demonstrated in 1984 on carbon monoxide recombination with myoglobin.

Total reflection X-ray fluorescence

Total reflection X-ray fluorescence (TXRF) is an elemental analysis technique in which X-rays strike a sample on a polished carrier below the critical angle, enabling picogram trace-element detection.