Concepts for X-ray absorption spectroscopy

About this vocabulary

SKOS controlled vocabulary of concepts used in CDIF X-ray Absorption Spectroscopy metadata records. Concepts that correspond to a class in the NeXus ontology carry a foaf:focus link for the Nexus class URI; note that these URIs do not resolve but the identified owl:Class entities are defined in the NeXus ontology. Others (physics concepts, XDI column definitions, sample properties Nexus doesn't model) exist as XAS-specific extensions.

Namespace: https://w3id.org/cdif/xas/CDIF4XAS_Reference_Concepts
Concepts: 105
Source: XAS_Glossary_SKOS.json

Absorption coefficientmutrans

https://w3id.org/cdif/xas/absorptioncoefficient

Definition: A coefficient μ(E) calculated as the natural log of the ratio of incident over transmitted x-ray intensity, divided by the thickness of the sample.
Narrower: Electron yield absorption coefficient
References: https://dictionary.iucr.org/Absorption_Coefficient

Analyzer crystal

https://w3id.org/cdif/xas/analyzercrystal

Definition: Crystal used to energy-analyze emitted fluorescence in high energy resolution fluorescence detected measurement, distinct from the monochromator crystal that selects the incident energy.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_herfd.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_herfd.html

Analyzer diameter

https://w3id.org/cdif/xas/analyzerdiameter

Definition: Diameter of the crystal analyzer wafer.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_herfd.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_herfd.html

Analyzer geometry

https://w3id.org/cdif/xas/analyzergeometry

Definition: Type of crystal analyzer geometry, such as Johann or Johansson.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_herfd.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_herfd.html

Beam spot size

https://w3id.org/cdif/xas/spotsize

Definition: Transverse size of the X-ray beam at the sample position.
References: https://doi.org/10.5281/zenodo.14920226

Beamline

https://w3id.org/cdif/xas/beamline

Definition: Part of a facility that delivers a high-intensity, tunable X-ray beam from an electron storage ring (synchrotron) to an experimental station where a sample is placed for analysis.
Note: Beamlines are the facilities at which crystallographers and other researchers get access to the tunable and high-intense X-ray beams they need for their research. http://csrri.iit.edu/~howard/itp/itpmacro.html
foaf:focus: http://purl.org/nexusformat/definitions/BaseClass/NXbeam
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: http://csrri.iit.edu/~howard/itp/itpmacro.html
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXbeam.html

Beamline energy range

https://w3id.org/cdif/xas/energyrange

Definition: The range of X-ray photon energies deliverable at the beamline.
References: https://doi.org/10.5281/zenodo.14920226

Beamline flux

https://w3id.org/cdif/xas/flux

Definition: The total number of photons or particles passing through a given area per second: Source intensity/area (example: s-1 cm-2). Distinct from photon flux -- the total number of photons (intensity) traveling down the beamline per second (photons per s). Photon flux might be labeled Beamline flux.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsource/flux
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsource.html#nxsource-flux-field

Beamline scan mode

https://w3id.org/cdif/xas/scanmode

Definition: The way in which XAS spectra are collected from the sample — e.g. continuous scan, step-scan, or energy-dispersive measurement mode.
References: https://doi.org/10.5281/zenodo.14920226

Beamline website

https://w3id.org/cdif/xas/website

Definition: Web URL for beamline information or documentation.
References: https://doi.org/10.5281/zenodo.14920226

Bending radius

https://w3id.org/cdif/xas/bendingradius

Definition: Bending radius of a spherically bent crystal analyzer. In Johann geometry this is twice the Rowland radius.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_herfd.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_herfd.html

Bragg angle

https://w3id.org/cdif/xas/braggangle

Definition: Bragg angle of the nominal reflection of a crystal analyzer.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_herfd.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_herfd.html

Calculated

https://w3id.org/cdif/xas/calculated

Definition: Boolean value, true if the property value is derived by calculations after the measurement event.
References: https://docs.xrayabsorption.org/NXxas/Q2XAFS2024_data.pdf
References: https://doi.org/10.5281/zenodo.14920226

Collimation

https://w3id.org/cdif/xas/collimation

Definition: Technique used to limit the incident x-ray beam to the required dimensions and angular spread.
Note: beamline property, describe the arrangement of absorbers used for collimation (https://doi.org/10.1351/goldbook.C01154). From XDI dictionary 'A concise statement of how beam collimation is provided' . A collimated beam of electromagnetic radiation has parallel rays, and therefore will spread minimally as it propagates. (https://en.wikipedia.org/wiki/Collimated_beam). Collimators are divided according to shape, energy, spatial resolution and sensitivity of collimator. This is determined by the thickness of collimator, hole density, and thickness of partitions. According to shape collimators can be: --- multi-hole collimator with parallel holes: collimator with thousands of holes, which are in a parallel axis with detector. Detector image has the same size. This is the most often used collimator. --- divergent collimator: collimator with holes diverging towards the radiation source. It allows to gain bigger picture than surface of crystal, but it is smaller sensitivity and spatial resolution-It takes up an area larger than the area of the detector. --- convergent collimator: collimator with holes converging to radiation source. That´s what we get enlarged picture of little organ with an increased sensitivity and a spatilal resolution-It spreads a small area of the object over a larger area of the detector. --- pinhole collimator: funnel-shaped collimator with diametr hole 3-5 mm. It provides enlarged picture wit the highest positional resolution, but there is low sensitivity (extends examination time). It is extended time of examination. It is inteded for observation of small organs (for example, thyroid gland, testicles). --- fan beam collimator: this type has focus in transversal direction while it is parallel in axial direction; has more than 50% higher spatial resolution than parallel type. It is used in cerebral computer tomography. Thickness of the collimator varies in line with the energy of the emmiter. A low energy collimator paired with a high energy emmiter would leak photons an cause blur in the signal (https://www.wikilectures.eu/w/Collimator, https://doi.org/10.1351/goldbook.C01155)
foaf:focus: http://purl.org/nexusformat/definitions/BaseClass/NXcollimator
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://en.wikipedia.org/wiki/Collimated_beam
References: https://doi.org/10.1351/goldbook.C01154
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXcollimator.html

Count time

https://w3id.org/cdif/xas/counttime

Definition: Detector live time per energy point: the interval during which the detector is actively counting.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_pfy.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_pfy.html

D spacing

https://w3id.org/cdif/xas/dspacing

Definition: Spacing between crystal planes of the monochromator's crystalline material that reflect x-rays.
Note: monochromator crystal property. 'The spacing between atomic planes within the crystal. By satisfying Bragg's Law (nλ = 2d sinθ), the monochromator selects a desired wavelength (λ) of radiation from an incident beam, where 'd' is the atomic plane spacing and 'θ' is the Bragg angle.'(Google AI overview). The perpendicular distance between two successive planes on a family (hkl). (https://dictionary.iucr.org/Interplanar_spacing)
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXcrystal/d_spacing
References: https://dictionary.iucr.org/Interplanar_spacing
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXcrystal.html#nxcrystal-d-spacing-field

Dead time

https://w3id.org/cdif/xas/deadtime

Definition: Detector dead time per energy point: the interval during which the detector cannot register further events.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_pfy.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_pfy.html

Detector calibration method

https://w3id.org/cdif/xas/calibrationmethod

Definition: Information detailing how raw detector signals were mathematically mapped into final pixel coordinates or energy bins, identifies the mathematical models used to correct spatial or geometric distortions (such as polynomial equations) and provides a reference link or file path to the exact coefficients and calibration logs used during data processing. (edited from Google AI)
foaf:focus: http://purl.org/nexusformat/definitions/Group/NXdetector/calibration_method
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXdetector.html#nxdetector-calibration-method-group

Detector method for incident fluxdetector.i0

https://w3id.org/cdif/xas/detectori0

Definition: The detection method used to measure the incident X-ray flux i0 (a monitor before the sample) — e.g. an ionization chamber filled with a specific gas mixture.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Detector method for transmitted fluxdetector.it

https://w3id.org/cdif/xas/detectorit

Definition: The detection method used to measure the transmitted X-ray flux it downstream of the sample — e.g. an ionization chamber filled with a specific gas mixture.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Detector type

https://w3id.org/cdif/xas/detectortype

Definition: Kind of detector used to measure X-ray intensities.
Note: property of detector instrument; description of how x-ray intensity is measured. NEXUS examples: He3 gas cylinder, He3 PSD, scintillator, fission chamber, proportion counter, ion chamber, ccd, pixel, image plate, CMOS.
References: https://doi.org/10.5281/zenodo.14920226

Edge analyzed

https://w3id.org/cdif/xas/edgeanalyzed

Definition: Target absorption edge.
Note: The 'edge' is a sudden increase in x-ray absorption occurring when the energy of incident X-rays is just above the binding energy of the targeted electron shell of the atoms interacting with the photons. vocabulary from XDI spec: {K, L, L1, L2, L3, M, M1, M2, M3, M4, M5, N, N1, N2, N3, N4, N5, N6, N7, O, O1, O2, O3, O4, O5, O6, O7}. Used in XDI and NeXus to refer to the shell of the atom where the electron hole is created (K, L, etc). The absorption edge is defined as K, L, L1, etc. That indicates the electronic energy levels involved in the absorption. The edge_energy tells us how much is the value of the energy of the electronic energy levels involved in that particular absorption edge. see https://xrayabsorption.org/xraytable/
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226
References: https://w3id.org/cdif/xas/XAS_AbsorptionEdges

Edge energy

https://w3id.org/cdif/xas/edgeenergy

Definition: The absorption edge as used in the data acquisition software.(XDI dictionary)
Note: An absorption edge is the energy at which there is a sharp rise (discontinuity) in the (linear) absorption coefficient of X-rays by an element, which occurs when the energy of the photon corresponds to the energy of a shell of the atom (K, LI, LII, LIII, etc. corresponding to the creation of electron holes in the 1s, 2s, 2p1/2, 2p3/2 etc. atomic subshells). Associated with this transition is the absorption threshold (q.v.) characterized by the corresponding energy E0. (https://doi.org/10.1351/goldbook.08767, https://dictionary.iucr.org/Absorption_edge). Discussed in team meeting 2025-09-08; general sense in group is that this is a known quantity specified for experiment design, not a measured result.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.1351/goldbook.08767
References: https://dictionary.iucr.org/Absorption_edge
References: https://doi.org/10.5281/zenodo.14920226

Electron yield absorption coefficient

https://w3id.org/cdif/xas/electronyieldabsorptioncoefficient

Definition: Absorption coefficient derived from electron yield, proportional to the ratio of the electron yield intensity and the incident beam intensity.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_tey.
Broader: Absorption coefficient
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_tey.html

Electron yield intensityiey

https://w3id.org/cdif/xas/electronyieldintensity

Definition: Intensity measured as the drain current or total electron current from electrons emitted by the sample surface, used to derive the absorption coefficient in electron-yield detection.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_tey.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_tey.html

Element analyzed

https://w3id.org/cdif/xas/elementanalyzed

Definition: Element that is the target for observing an x-ray absorption edge.
Note: Element being analyzed. A species of atoms; all atoms with the same number of protons in the atomic nucleus. (https://doi.org/10.1351/goldbook.C01022). Suggest using SWEET vocabulary:http://sweetontology.net/matrElement/ for values
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.1351/goldbook.C01022
References: https://doi.org/10.5281/zenodo.14920226

Emission energy

https://w3id.org/cdif/xas/emissionenergy

Definition: Emission energy at which the spectrometer is set in high energy resolution fluorescence detected measurement.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_herfd.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_herfd.html

Emission energy window

https://w3id.org/cdif/xas/emissionenergywindow

Definition: Lower and upper bounds of the detected emission energy window: the energy range over which fluorescence photons are accepted, whether defined by a detector channel range or a spectrometer region of interest.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_pfy.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_pfy.html

Emission lineemissionline

https://w3id.org/cdif/xas/emissionline

Definition: X-ray emission line observed when a core vacancy is filled, identified by the initial and final edge. Used to specify the detected emission in partial fluorescence yield and high energy resolution fluorescence detected measurements.
References: https://w3id.org/cdif/xas/XAS_EmissionLines

Energy error

https://w3id.org/cdif/xas/energyerror

Definition: The difference between the intended energy selected by a monochromator and the actual energy measured at the sample (the incident intensity)
Note: NEXUS comment is 'energy standard deviation' (nxs: Field/NXmonochromator/energy_error), or 'uncertaities associated to energy' (from https://github.com/nexusformat/definitions/issues/820); note this is apparently different from our definition here.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXmonochromator/energy_error
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXmonochromator.html#nxmonochromator-energy-error-field

Energy resolution

https://w3id.org/cdif/xas/energyresolution

Definition: The ability of a spectrometer to distinguish between two closely spaced X-ray photon energies.
References: https://doi.org/10.5281/zenodo.14920226

EXAFS function chi(k)chi

https://w3id.org/cdif/xas/exafsfunction

Definition: A function representing the Extended X-ray Absorption Fine Structure (EXAFS) oscillations in k-space It represents the modulation of the X-ray absorption coefficient (isolated and normalized) due to the scattering of a photoelectron wave by neighboring atoms, expressed as a function of the photoelectron wavevector (k).
Note: XDI Column.chi: EXAFS oscillatory function chi(k).
References: Ravel, B., & Newville, M. (2005). ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT. Journal of Synchrotron Radiation, 12(4), 537-541.
References: https://en.wikipedia.org/wiki/Extended_X-ray_absorption_fine_structure
References: https://doi.org/10.5281/zenodo.14920226

Experiment documentation

https://w3id.org/cdif/xas/experimentdocumentation

Definition: Description of the full experiment (document in pdf, latex, ...)
foaf:focus: http://purl.org/nexusformat/definitions/Group/NXentry/experiment_documentation
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXentry.html#nxentry-experiment-documentation-group

Facility

https://w3id.org/cdif/xas/facility

Definition: A synchrotron, X-ray free electron laser, or laboratory facility where XAS measurements are performed.
References: https://docs.xrayabsorption.org/NXxas/Q2XAFS2024_data.pdf
References: https://doi.org/10.5281/zenodo.14920226

Facility current

https://w3id.org/cdif/xas/facilitycurrent

Definition: Accelerator, X-ray tube, or storage ring current; property of a facility
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsource/current
References: https://docs.xrayabsorption.org/NXxas/Q2XAFS2024_data.pdf
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsource.html#nxsource-current-field

Facility energy

https://w3id.org/cdif/xas/facilityenergy

Definition: The energy of the current stored in the synchrotron storage ring. (XDI)
Note: in XDI this is a property of the Facility, so include 'facility' prefix. The beam energy is the product of the ring current (particle flux, typically electrons) and the particle energy. The beam energy is reported in Joules, particle energe typically in electron volts. Have to look at example data to determine how this is being used.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsource/energy
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsource.html#nxsource-energy-field

Filtered chi imaginarychi_im

https://w3id.org/cdif/xas/filteredchiimaginary

Definition: Imaginary part of the Fourier-filtered Extended X-ray Absorption Fine Structure (EXAFS) oscillations chi(k) in k-space.
Note: XDI Column.chi_im: imaginary part of Fourier-filtered chi(k).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Filtered chi magnitudechi_mag

https://w3id.org/cdif/xas/filteredchimagnitude

Definition: Magnitude of the Fourier-filtered Extended X-ray Absorption Fine Structure (EXAFS) oscillations chi(k). Fourier filtering isolates contributions from specific R-space shells before transforming back to k-space.
Note: XDI Column.chi_mag: magnitude of Fourier-filtered chi(k).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Filtered chi phasechi_pha

https://w3id.org/cdif/xas/filteredchiphase

Definition: Phase of the Fourier-filtered Extended X-ray Absorption Fine Structure (EXAFS) oscillations chi(k) in k-space.
Note: XDI Column.chi_pha: phase of Fourier-filtered chi(k).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Filtered chi realchi_re

https://w3id.org/cdif/xas/filteredchireal

Definition: Real part of the Fourier-filtered Extended X-ray Absorption Fine Structure (EXAFS) oscillations chi(k) in k-space.
Note: XDI Column.chi_re: real part of Fourier-filtered chi(k).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Fluorescence absorption coefficientmufluor

https://w3id.org/cdif/xas/fluorescenceabsorptioncoefficient

Definition: The fluorescence absorption coefficient is calculated as the natural log of the ratio of emitted fluorescence intensity over transmitted x-ray intensity, divided by the thickness of the sample.
Note: The fluorescence intensity is proportional to the absorbed fraction of the incident intensity. Fluorescence is preferred for dilute samples (trace element studies, biological samples, catalysts, geological samples), because the emitted fluorescence is element-specific.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://docs.xrayabsorption.org/NXxas/Q2XAFS2024_data.pdf
References: https://doi.org/10.5281/zenodo.14920226

Fluorescence intensityifluor

https://w3id.org/cdif/xas/fluorescenceintensity

Definition: A measured X-ray intensity emitted by a sample, following absorption of incident X-rays, due to fluorescence decay phenomena.
Note: Fluorescence is a physical phenomena. When X-rays are absorbed by a sample, they create excited electronic states. These states can decay, and one of the decay proceses is flourescence. When excited electrons decay in an atom by fluorescence, they emitt light, in this case, is X-ray light. (https://www.lehigh.edu/imi/teched/GlassCSC/SuppReading/Tutorials.pdf)
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://en.wikipedia.org/wiki/X-ray_fluorescence
References: https://doi.org/10.5281/zenodo.14920226

Flux measure method

https://w3id.org/cdif/xas/fluxmeasuremethod

Definition: Description of how the flux was measured.
Note: Property of detector, see https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md#defined-items-in-the-detector-namespace, tags for i0, it, if, ir
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Focusing

https://w3id.org/cdif/xas/focusing

Definition: A concise statement about how beam focusing is provided. (XDI)
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Fourier-transformed chi imaginarychir_im

https://w3id.org/cdif/xas/ftchiimaginary

Definition: Imaginary part of the Fourier-transformed Extended X-ray Absorption Fine Structure (EXAFS) oscillations chi(R) in R-space, obtained without applying corrections for phase shifts.
Note: XDI Column.chir_im: imaginary part of Fourier transform of chi(k).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://en.wikipedia.org/wiki/Fourier_transform
References: https://doi.org/10.5281/zenodo.14920226

Fourier-transformed chi magnitudechir_mag

https://w3id.org/cdif/xas/ftchimagnitude

Definition: Magnitude of the Fourier-transformed Extended X-ray Absorption Fine Structure (EXAFS) oscillations chi(R) in R-space, obtained without applying corrections for phase shifts.
Note: XDI Column.chir_mag: magnitude of Fourier transform of chi(k), i.e. |chi(r)|.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://en.wikipedia.org/wiki/Fourier_transform
References: https://doi.org/10.5281/zenodo.14920226

Fourier-transformed chi phasechir_pha

https://w3id.org/cdif/xas/ftchiphase

Definition: Phase of the Fourier-transformed Extended X-ray Absorption Fine Structure (EXAFS) oscillations chi(R) in R-space, obtained without applying corrections for phase shifts.
Note: XDI Column.chir_pha: phase of Fourier transform of chi(k).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://en.wikipedia.org/wiki/Fourier_transform
References: https://doi.org/10.5281/zenodo.14920226

Fourier-transformed chi realchir_re

https://w3id.org/cdif/xas/ftchireal

Definition: Real part of the Fourier-transformed Extended X-ray Absorption Fine Structure (EXAFS) oscillations chi(R) in R-space, obtained without applying corrections for phase shifts.
Note: XDI Column.chir_re: real part of Fourier transform of chi(k).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://en.wikipedia.org/wiki/Fourier_transform
References: https://doi.org/10.5281/zenodo.14920226

Harmonic rejection

https://w3id.org/cdif/xas/harmonicrejection

Definition: A statement explaining how unwanted higher-energy X-ray harmonics are removed from the probe beam.
Note: X-ray absorption harmonic rejection is the process of eliminating unwanted higher-energy X-ray harmonics from a beam (Google AI overview). Harmonics are x-rays that have a frequency that is a positive integer multiple of the desired probe frequency. The requirement of a high spectral purity of the X-ray beam to be delivered to the sample makes it essenstial to reduce the harmonic content of the beam. https://www.diamond.ac.uk/Instruments/Spectroscopy/I20/XAS_XES_Branchline/Specification.html
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Incident intensityi0

https://w3id.org/cdif/xas/incidentintensity

Definition: The measured X-ray intensity before it interacts with the sample.
Note: Measured by an ionization chamber (gas-filled detector) or photodiode placed before the sample. (X-Ray Absorption Spectroscopy of Semiconductors [book] Chapter 1: Introduction to X-Ray Absorption Spectroscopy, First Online: 01 January 2014 pp 1–26)
References: https://doi.org/10.1007/978-3-662-44362-0
References: https://doi.org/10.5281/zenodo.14920226

Installed options

https://w3id.org/cdif/xas/installedoptions

Definition: Description of optional equipment installed on the base instrument for this measurement (e.g. sample cells, in-situ environment components).
References: https://docs.xrayabsorption.org/NXxas/Q2XAFS2024_data.pdf
References: https://doi.org/10.5281/zenodo.14920226

Instrument

https://w3id.org/cdif/xas/instrument

Definition: A device or a combination of devices used to carry out an analytical process.
Note: The analytical process encompasses all steps from the introduction of the sample or the test portion to the production of the result. An analytical instrument may carry out single or multiple analytical procedures. In the latter case it may be selective, i.e. designed to carry out any requested combination of procedures within the set, on each specimen. (https://doi.org/10.1351/goldbook.A00333) NXInstrument has 'Collection of the components of the instrument or beamline'. Does make clear that an instrument has parts.
foaf:focus: http://purl.org/nexusformat/definitions/BaseClass/NXinstrument
References: https://doi.org/10.1351/goldbook.A00333
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXinstrument.html

Intensity uncertainty

https://w3id.org/cdif/xas/intensityuncertainty

Definition: Errors associated with the intensity of the spectrum.
Note: Definition adapted from the NeXus NXDL documentation in NXxas.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas.html

Monitor mode

https://w3id.org/cdif/xas/monitormode

Definition: Algorithm for aggregating data in detectors measuring excitation and sample response
Note: Count to a preset value based on either clock time (timer) or received monitor counts (monitor).
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXmonitor/mode
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXmonitor.html#nxmonitor-mode-field

Monitor preset

https://w3id.org/cdif/xas/monitorpreset

Definition: Configuration of monitor mode
Note: Either counting time or preset count value.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXmonitor/preset
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXmonitor.html#nxmonitor-preset-field

Monochromator angleangle

https://w3id.org/cdif/xas/monochromatorangle

Definition: The Bragg angle of the monochromator crystal, related to selected photon energy via Bragg's law nλ = 2d sin(θ).
Note: XDI Column.angle: mono angle (degrees / radians / steps).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Monochromator chemical formula

https://w3id.org/cdif/xas/monochromatorchemicalformula

Definition: The chemical formula [of the monochromator material] specified using [Crystallographic Information File] CIF conventions.
Note: Mochromator crystal property. NOTE-- seems redundant with NXcrystal/type. CIF conventions at https://www.iucr.org/resources/cif/spec/version1.1
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXcrystal/chemical_formula
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXcrystal.html#nxcrystal-chemical-formula-field

Monochromator energyenergy

https://w3id.org/cdif/xas/monochromatorenergy

Definition: The energy selected by the X-ray monochromator and delivered to the sample during an absorption scan.
Note: This is the independent variable in an XAS scan. NEXUS comment is 'energy selected'. An energy monochromator is a critical component that selects a specific, monochromatic X-ray energy from an X-ray beam. Notes: Typically a Bragg crystal monochromator is used. This energy is continuously tunable and determines the energy at which absorption measurements are performed, enabling precise probing of core-level electronic transitions near an element’s absorption edge. In XAS, monochromator energy is critical for scanning across absorption edges to extract fine structural information such as XANES and EXAFS. The energy is selected using Bragg’s Law: lambda = 2d*sin(theta) $$ where lambda is the X-ray wavelength, dd is the crystal lattice spacing, and theta is the angle of incidence. The Incident Energy variable reports the measured energy delivered to the sample. (International Tables for Crystallography, Vol. I, Chapter 3.4 )
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXmonochromator/energy
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXmonochromator.html#nxmonochromator-energy-field

Monochromator type

https://w3id.org/cdif/xas/monochromatortype

Definition: Type or material of monochromating substance.
Note: monochromator crystal property; values reported in NEXUS as of 2010-11-17 {PG (Highly Oriented Pyrolytic Graphite) | Ge | Si | Cu | Fe3Si | CoFe | Cu2MnAl (Heusler) | Multilayer | Diamond.}
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXcrystal/type
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXcrystal.html#nxcrystal-type-field

Normalized fluorescence absorption coefficientnormfluor

https://w3id.org/cdif/xas/normalizedfluorescenceabsorptioncoefficient

Definition: The normalized fluorescence-yield absorption coefficient µ(E), rescaled to unit edge-step.
Note: XDI Column.normfluor: normalized mu fluorescence.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Normalized reference absorption coefficientnormrefer

https://w3id.org/cdif/xas/normalizedreferenceabsorptioncoefficient

Definition: The normalized reference-channel absorption coefficient µ(E), rescaled to unit edge-step.
Note: XDI Column.normrefer: normalized mu reference.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Normalized transmission absorption coefficientnormtrans

https://w3id.org/cdif/xas/normalizedtransmissionabsorptioncoefficient

Definition: The normalized transmission-mode absorption coefficient µ(E), rescaled to unit edge-step so spectra can be compared across samples.
Note: XDI Column.normtrans: normalized mu transmission.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Parent sample

https://w3id.org/cdif/xas/parentsample

Definition: Identifier for a material sample from which the analyzed sample was derived.
Note: A composite or aggregate sample might have multiple parent samples.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Porosity

https://w3id.org/cdif/xas/porosity

Definition: The fraction of the sample volume that is empty space (pore space)
Note: Material property of sample. Expressed as a fraction between 0 and 1, or as a percentage between 0% and 100%.. See also https://doi.org/10.1351/goldbook.P04762.
References: https://doi.org/10.1351/goldbook.P04762
References: https://doi.org/10.5281/zenodo.14920226

Pressure

https://w3id.org/cdif/xas/pressure

Definition: Normal force acting on a surface divided by the area of that surface.
Note: Environmental condition of sample during analysis. For a mixture of gases the contribution by each constituent is called the 'partial pressure'. https://doi.org/10.1351/goldbook.P04819
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/pressure
References: https://doi.org/10.1351/goldbook.P04819
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-pressure-field

Probe

https://w3id.org/cdif/xas/probe

Definition: type of radiation probe. Eenumerated list: {neutron, photon, x-ray, muon, electron, ultraviolet, visible light, positron, proton} Default is x-ray for XAS.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsource/probe
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsource.html#nxsource-probe-field

Radial distancer

https://w3id.org/cdif/xas/radialdistance

Definition: The R-space (radial distance space) coordinate of the Extended X-ray Absorption Fine Structure (EXAFS) oscillations, obtained by performing the Fourier transform of chi(k) in k-space. Peaks in |chi(R)| correspond to backscattering shells around the absorbing atom.
Note: XDI Column.r: radial distance from absorbing atom (typically Angstroms).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://en.wikipedia.org/wiki/Extended_X-ray_absorption_fine_structure
References: https://doi.org/10.5281/zenodo.14920226

Reference absorption coefficientmurefer

https://w3id.org/cdif/xas/referenceabsorptioncoefficient

Definition: Absorption coefficient µ(E) of the reference channel, calculated from ln(it / iref).
Note: XDI Column.murefer: absorption coefficient computed from the reference-channel intensity.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Reference intensityirefer

https://w3id.org/cdif/xas/referenceintensity

Definition: measured x-ray intensity after passing through a reference sample with know absorption characteristics.
Note: Use to calibrate monochromator energy, check for drift in incident energry.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Reflection plane

https://w3id.org/cdif/xas/reflectionplane

Definition: Miller indices (hkl) of the reflecting plane used by the monochromator crystal.
Note: Monochromator crystal property. It’s not a physical surface, but a mathematical construct based on the periodic arrangement of atoms. A classic example of a reflection plane in crystallography is the (100) plane in a cubic crystal system. Miller index: (100), Interpretation: This plane intersects the x-axis at 1 unit, and is parallel to both the y- and z-axes (i.e., it never intersects them). Physical meaning: It represents a set of atomic layers perpendicular to the x-axis, spaced at regular intervals. Examples of Crystals used for X-ray monochromators: Si(111), Si(220), Si(311), Ge(111) https://www.iucr.org/__data/assets/pdf_file/0004/60637/IUCr2011-XAFS-Tutorial_-Ascone.pdf
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXcrystal/reflection
References: https://www.iucr.org/__data/assets/pdf_file/0004/60637/IUCr2011-XAFS-Tutorial_-Ascone.pdf
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXcrystal.html#nxcrystal-reflection-field

Retarding voltage

https://w3id.org/cdif/xas/retardingvoltage

Definition: Retarding voltage (bias) applied to select electrons above a kinetic energy threshold, discriminating against low-energy secondary electrons in partial electron yield detection.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_pey.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_pey.html

Rowland radius

https://w3id.org/cdif/xas/rowlandradius

Definition: Radius of the Rowland circle, on which the sample, crystal centre and detector focus all lie.
Note: Definition adapted from the NeXus NXDL documentation in NXxas_herfd.
See also: https://manual.nexusformat.org/classes/contributed_definitions/NXxas_herfd.html

Sample analysis event

https://w3id.org/cdif/xas/sampleanalysisevent

Definition: An event in which one or more properties of a prepared material sample are measured.
Note: Note, label as 'sample analysis event' to distinguish from 'Analysis' as scientific activity to interpret data. 'A detailed examination or study of something so as to determine its nature, structure, or essential features.' (Oxford English Dictionary)
References: https://docs.xrayabsorption.org/NXxas/Q2XAFS2024_data.pdf
References: https://doi.org/10.5281/zenodo.14920226

Sample chemical composition

https://w3id.org/cdif/xas/samplechemicalcomposition

Definition: Chemical formula for sample material
Note: As with Monochromator, use CIF conventions. Note: 'Stoichiometry is the relationships between the quantities of reactants and products before, during, and following chemical reactions.'(Wikipedia). Not sure that's the label we want for this property...Recommend renaming 'sample chemical composition'.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample concentration

https://w3id.org/cdif/xas/concentration

Definition: Concentration of a component in the composition of a sample
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/concentration
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-concentration-field

Sample crystal structure

https://w3id.org/cdif/xas/samplecrystalstructure

Definition: Crystallographic point or space group that characterizes the crystal structure of the sample.
Note: A 3-D pattern of points consisting of atoms that obeys the conditions of periodicity and discreteness expressed by a set of symmetry operations (https://dictionary.iucr.org/Crystal_structure). Point groups describe the symmetry of a point without translations, always leaving at least one point fixed; space groups describe the symmetry of a crystal lattice allowing translations. In three dimensions, there are 32 crystallographic point groups, and 230 unique space groups (ChatGPT) . Various notation systems are used to classify these groups (Wikipedia).
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/unit_cell
References: https://doi.org/10.1007/978-3-642-13281-0
References: https://dictionary.iucr.org/Unit_cell
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-unit-cell-field

Sample density

https://w3id.org/cdif/xas/density

Definition: Density of sample
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/density
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-density-field

Sample description

https://w3id.org/cdif/xas/sampledescription

Definition: Free-text description of the sample. Broader than sample preparation: it may record the sample's form, dimensions, provenance or identity as well as how it was prepared.
Note: Grounded in the NeXus NXDL documentation for NXsample/description, 'Description of the sample'. Minted 2026-07-28 because the glossary had no general free-text sample concept, which forced samplepreparation into a closeMatch against that field. XDI has no counterpart tag; its Sample.prep text maps to samplepreparation.
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html

Sample electric field

https://w3id.org/cdif/xas/electricfield

Definition: Electric field applied to sample during analysis. Represented with x, y, z voltage components.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/electric_field
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-electric-field-field

Sample electrochemical potential

https://w3id.org/cdif/xas/electrochemicalpotential

Definition: Applied electrochemical potential at the sample during measurement.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample magnetic field

https://w3id.org/cdif/xas/magneticfield

Definition: magnetic_field.value is a link to e.g. magnetic_field_env.sensor1.value
foaf:focus: http://purl.org/nexusformat/definitions/Group/NXsample/magnetic_field
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-magnetic-field-group

Sample magnetic moment

https://w3id.org/cdif/xas/magneticmoment

Definition: Magnetic moment measured on the sample.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample mass

https://w3id.org/cdif/xas/samplemass

Definition: Mass of the sample.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/mass
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-mass-field

Sample material

https://w3id.org/cdif/xas/samplematerial

Definition: Type of substance that constitutes the sample.
Note: Material type encompasses state of matter. E.g. See iSamples material type vocabulary (https://vocabs.ardc.edu.au/viewById/664). See also https://doi.org/10.1351/goldbook.12297
References: https://doi.org/10.1351/goldbook.12297
References: https://doi.org/10.5281/zenodo.14920226

Sample opacity

https://w3id.org/cdif/xas/opacity

Definition: Opacity of the sample material relative to the incident X-ray beam.
Note: Dimensionless: a ratio relative to the incident beam. Stated here because the file formats do not record a unit for this quantity, so a consumer cannot otherwise tell 'dimensionless' from 'unit not recorded'.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample pH

https://w3id.org/cdif/xas/ph

Definition: pH of the sample environment (if a liquid or a wet cell).
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample point group

https://w3id.org/cdif/xas/pointgroup

Definition: Crystallographic point group, deprecated if space_group present
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/point_group
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-point-group-field

Sample preparation

https://w3id.org/cdif/xas/samplepreparation

Definition: The method of sample preparation.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample redox potential (Eh)

https://w3id.org/cdif/xas/eh

Definition: Redox potential Eh of the sample environment.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample resistivity

https://w3id.org/cdif/xas/resistivity

Definition: Electrical resistivity of the sample.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample temperature

https://w3id.org/cdif/xas/temperature

Definition: Sample temperature. This could be a scanned variable
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/temperature
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-temperature-field

Sample thickness

https://w3id.org/cdif/xas/samplethickness

Definition: Length of sample material in the direction of incident x-rays.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/thickness
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-thickness-field

Sample unit cell

https://w3id.org/cdif/xas/sampleunitcell

Definition: [Crystallographic] Unit cell parameters (lengths and angles) (NEXUS)
Note: 'unit cell is a region that just fills space without any overlapping when translated through some subset of the vectors of a Bravais lattice.' (Ashcroft, Neil W. (1976). 'Chapter 4'. Solid State Physics. W. B. Saunders Company. p. 73)
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsample/unit_cell
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsample.html#nxsample-unit-cell-field

Sample viscosity

https://w3id.org/cdif/xas/viscosity

Definition: Viscosity of the sample if a liquid.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Sample volume

https://w3id.org/cdif/xas/volume

Definition: Volume of the sample material analyzed.
References: https://github.com/XraySpectroscopy/XAS-Data-Interchange/blob/master/specification/dictionary.md
References: https://doi.org/10.5281/zenodo.14920226

Source

https://w3id.org/cdif/xas/source

Definition: A device that generates X-rays or other types of radiation used to probe a sample.
Note: E.g. storage ring (synchrotron), x-ray tube.
foaf:focus: http://purl.org/nexusformat/definitions/BaseClass/NXsource
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsource.html

Synchrotron facility

https://w3id.org/cdif/xas/synchrotonfacility

Definition: Installation that delivers a high-intensity, tunable X-ray beam from an electron storage ring (synchrotron) to an experimental station where a sample is placed for analysis.
Note: A place that hosts instruments and other necessary components to support XAS research. NEXUS comment is 'The neutron or x-ray storage ring/facility'
foaf:focus: http://purl.org/nexusformat/definitions/BaseClass/NXsource
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsource.html

Transmitted intensityitrans

https://w3id.org/cdif/xas/transmittedintensity

Definition: The measured X-ray intensity transmitted through a sample.
Note: The the change in x-ray intensity depends on the distance the x-ray beams travels through the sample.
References: https://www.esrf.fr/files/live/sites/www/files/events/conferences/2016/Summer%20school%202016/Summerschool%202016%20-%20Pascarelli.pdf
References: https://doi.org/10.5281/zenodo.14920226

Wavenumberk

https://w3id.org/cdif/xas/wavenumber

Definition: The photoelectron wavenumber (k) represents the spatial frequency of the emitted photoelectron wave, calculated from the kinetic energy above the absorption edge.
Note: XDI Column.k: photoelectron wavenumber (typically inverse Angstroms).
References: Bunker, G. (2010). Introduction to X-ray Absorption Fine Structure Spectroscopy. Cambridge University Press.
References: https://en.wikipedia.org/wiki/Wavenumber
References: https://doi.org/10.5281/zenodo.14920226

X-ray detector

https://w3id.org/cdif/xas/xraydetector

Definition: A device for detecting the presence of X-Rays and measureing their intensity.
Note: NEXUS has 'A detector, detector bank, or multidetector.' which is not a definition.
foaf:focus: http://purl.org/nexusformat/definitions/BaseClass/NXdetector
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXdetector.html

X-ray monitor

https://w3id.org/cdif/xas/xraymonitor

Definition: An instrument that acquires data to characterize the incident x-ray beam.
foaf:focus: http://purl.org/nexusformat/definitions/BaseClass/NXmonitor
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXmonitor.html

X-ray monochromator

https://w3id.org/cdif/xas/xraymonochromator

Definition: Device used to eliminate X-rays of energies other than those in a narrow energy or wavelength band.
Note: A device for isolating a narrow portion of a spectrum (Merriam-Webster). A device that transmits a selectable narrow band of wavelengths of light or other radiation chosen from a wider range of wavelengths available at the input. [Wikipedia] see also https://doi.org/10.1351/goldbook.09304.
foaf:focus: http://purl.org/nexusformat/definitions/BaseClass/NXmonochromator
References: https://en.wikipedia.org/wiki/Crystal_monochromator
References: https://doi.org/10.1351/goldbook.09304
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXmonochromator.html

X-ray source type

https://w3id.org/cdif/xas/xraysourcetype

Definition: Type of radiation source.
Note: One of {'Spallation Neutron Source' , 'Pulsed Reactor Neutron Source' , 'Reactor Neutron Source' , 'Synchrotron X-ray Source' , 'Pulsed Muon Source' , 'Rotating Anode X-ray' , 'Fixed Tube X-ray' , 'UV Laser' , 'Free-Electron Laser' , 'Optical Laser' , 'Ion Source' , 'UV Plasma Source' , 'Metal Jet X-ray'} Another possible type is 'APS (Advanced Photon Source) bending magnet', which would appear to be a subclass of 'Synchrotron X-ray Source'.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXsource/type
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/base_classes/NXsource.html#nxsource-type-field

XAS analysis event

https://w3id.org/cdif/xas/analysisevent

Definition: The execution of an X-ray absorption spectroscopy experiment, which is essentially a scan on energy (transmitted, fluorescent...) versus incoming/absorbed beam.
foaf:focus: http://purl.org/nexusformat/definitions/Application/NXxas
References: https://docs.xrayabsorption.org/NXxas/Q2XAFS2024_data.pdf
References: https://doi.org/10.5281/zenodo.14920226
See also: https://manual.nexusformat.org/classes/applications/NXxas.html

XAS measurement mode

https://w3id.org/cdif/xas/xasmeasurementmode

Definition: Detection method used for observing the sample absorption.
Note: Property of experiment; controlled list of process being monitored to obtain the spectrum. One of {'Total Electron Yield' , 'Partial Electron Yield' , 'Auger Electron Yield' , 'Fluorescence Yield' , 'Transmission'}.
foaf:focus: http://purl.org/nexusformat/definitions/Field/NXxas/ENTRY/DATA/mode
References: https://doi.org/10.5281/zenodo.14920226
References: https://w3id.org/cdif/xas/XAS_DetectionModes
See also: https://manual.nexusformat.org/classes/applications/NXxas.html#nxxas-entry-data-mode-field