3.3.3.103. NXxas_herfd

Status:

application definition (contribution), extends NXxas

Description:

High-energy resolution fluorescence detection (HERFD) is a particular ...

High-energy resolution fluorescence detection (HERFD) is a particular case of partial fluorescence yield measured with a crystal analyzer spectrometer with an energy bandwidth of approximately 1-2 eV.

The HERFD spectrum corresponds to a constant-emission-energy cut through the Resonant Inelastic X-ray Scattering (RIXS) plane. The spectral shape depends on the emission energy, making the emission line and emission energy mandatory metadata.

The top-level intensity field stores the ratio \(I_f/I_0\), where \(I_f\) is the fluorescence intensity diffracted by the crystal analyzer(s) and \(I_0\) is the incident beam intensity. This ratio is proportional to the absorption coefficient:

\[\mu(E) \propto I_f/I_0\]

The spectrometer uses Rowland circle geometry (Johann or Johansson type). Multiple crystal analyzers may be arranged at different horizontal angles around the sample to increase solid angle coverage.

Symbols:

No symbol table

Groups cited:

NXbeam, NXcoordinate_system, NXcrystal, NXdetector, NXemission_line, NXentry, NXinstrument, NXprocess, NXsample, NXsource, NXtransformations

Structure:

ENTRY: (required) NXentry ⤆

definition: (required) NX_CHAR ⤆

Official NeXus NXDL schema to which this file conforms. ...

Official NeXus NXDL schema to which this file conforms.

Obligatory value: NXxas_herfd

intensity: (required) NX_FLOAT (Rank: 1, Dimensions: [nEnergy]) {units=NX_ANY} ⤆

The ratio :math:`I_f/I_0`, where :math:`I_f` is the ...

The ratio \(I_f/I_0\), where \(I_f\) is the fluorescence intensity diffracted by the crystal analyzer(s) and \(I_0\) is the incident beam intensity.

emission_line: (required) NXemission_line

The emission line at which the HERFD spectrum is measured.

emission_energy: (required) NX_FLOAT {units=NX_ENERGY}

The emission energy at which the spectrometer is set.

beamline_coordinate_system: (optional) NXcoordinate_system

Beamline coordinate system with the sample at the origin: ...

Beamline coordinate system with the sample at the origin: x along the beam, y horizontal, z opposite to gravity.

origin: (required) NX_CHAR ⤆

Obligatory value: sample

x_direction: (required) NX_CHAR ⤆

Obligatory value: along incident beam

y_direction: (required) NX_CHAR ⤆

Obligatory value: horizontal perpendicular to beam

z_direction: (required) NX_CHAR ⤆

Obligatory value: opposite to gravity

x: (required) NX_NUMBER {units=NX_LENGTH} ⤆

Obligatory value: [1, 0, 0]

y: (required) NX_NUMBER {units=NX_LENGTH} ⤆

Obligatory value: [0, 1, 0]

z: (required) NX_NUMBER {units=NX_LENGTH} ⤆

Obligatory value: [0, 0, 1]

depends_on: (required) NX_CHAR ⤆

Should point to ...

Should point to transformations/beam.

transformations: (optional) NXtransformations ⤆

Two rotations relating the beamline frame to ...

Two rotations relating the beamline frame to the NeXus laboratory frame, plus direction vectors labeling beam and gravity.

beam: (required) NX_NUMBER {units=NX_UNITLESS} ⤆

Direction of the incident beam in the beamline ...

Direction of the incident beam in the beamline coordinate system.

@vector: (required) NX_NUMBER ⤆

Obligatory value: [1, 0, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: gravity

gravity: (required) NX_NUMBER {units=NX_UNITLESS} ⤆

Direction of gravity in the beamline coordinate ...

Direction of gravity in the beamline coordinate system.

@vector: (required) NX_NUMBER ⤆

Obligatory value: [0, 0, -1]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: rotate_gravity_to_minus_y

rotate_gravity_to_minus_y: (required) NX_NUMBER {units=NX_ANGLE} ⤆

Active rotation moving gravity from the ...

Active rotation moving gravity from the beamline direction (-z) to the NeXus direction (-y).

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [1, 0, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: rotate_beam_to_plus_z

rotate_beam_to_plus_z: (required) NX_NUMBER {units=NX_ANGLE} ⤆

Active rotation moving the beam from the ...

Active rotation moving the beam from the beamline direction (+x) to the NeXus direction (+z).

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [0, 1, 0]

@depends_on: (required) NX_CHAR ⤆

Should point to ``.`` (the NeXus laboratory ...

Should point to . (the NeXus laboratory frame).

SAMPLE: (required) NXsample ⤆

depends_on: (optional) NX_CHAR ⤆

The sample is at the origin of the beamline ...

The sample is at the origin of the beamline coordinate system. Should point to /entry/beamline_coordinate_system.

INSTRUMENT: (optional) NXinstrument ⤆

beam: (optional) NXbeam ⤆

The incident X-ray beam.

depends_on: (optional) NX_CHAR ⤆

Should point to ...

Should point to beam/transformations/beam_direction.

transformations: (optional) NXtransformations ⤆

beam_direction: (required) NX_NUMBER {units=NX_UNITLESS} ⤆

Beam direction in the beamline coordinate ...

Beam direction in the beamline coordinate system. The beam travels along +x.

@vector: (required) NX_NUMBER ⤆

Obligatory value: [1, 0, 0]

@depends_on: (required) NX_CHAR ⤆

Should point to ...

Should point to /entry/beamline_coordinate_system or to /entry/sample.

SOURCE: (optional) NXsource ⤆

type: (required) NX_CHAR ⤆

name: (required) NX_CHAR ⤆

probe: (required) NX_CHAR ⤆

Obligatory value: x-ray

i0: (recommended) NXdetector ⤆

Detector measuring the incident beam intensity ...

Detector measuring the incident beam intensity \(I_0\), positioned upstream of the sample along the beam direction.

data: (required) NX_NUMBER (Rank: 1, Dimensions: [nEnergy]) ⤆

depends_on: (optional) NX_CHAR ⤆

Should point to ...

Should point to i0/transformations/i0_distance.

transformations: (optional) NXtransformations ⤆

i0_distance: (required) NX_NUMBER {units=NX_LENGTH} ⤆

Distance from the sample to the I0 detector, ...

Distance from the sample to the I0 detector, measured upstream along the beam (negative x direction in the beamline frame).

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: translation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [-1, 0, 0]

@depends_on: (required) NX_CHAR ⤆

Should point to /entry/sample.

ANALYZERCRYSTAL: (required) NXcrystal ⤆

Crystal analyzer on the Rowland circle. For ...

Crystal analyzer on the Rowland circle. For multi-crystal spectrometers, use one group per crystal (e.g. analyzer1, analyzer2).

type: (optional) NX_CHAR ⤆

Type or material of the analyzer crystal ...

Type or material of the analyzer crystal (Si, Ge, etc.).

reflection: (optional) NX_INT (Rank: 1, Dimensions: [3]) {units=NX_UNITLESS} ⤆

Miller indices (hkl) values of the nominal ...

Miller indices (hkl) values of the nominal reflection.

d_spacing: (optional) NX_FLOAT {units=NX_LENGTH} ⤆

The spacing between crystal planes of the ...

The spacing between crystal planes of the reflection.

bragg_angle: (optional) NX_FLOAT {units=NX_ANGLE} ⤆

Bragg angle :math:`\theta_B` of the nominal ...

Bragg angle \(\theta_B\) of the nominal reflection.

bending_radius: (optional) NX_FLOAT {units=NX_LENGTH}

Bending radius of the spherically bent crystal ...

Bending radius of the spherically bent crystal analyzer. In Johann geometry this is \(2R_R\) (twice the Rowland radius).

rowland_radius: (optional) NX_FLOAT {units=NX_LENGTH}

Radius of the Rowland circle :math:`R_R`. The ...

Radius of the Rowland circle \(R_R\). The sample, crystal center, and detector focus all lie on this circle.

energy_resolution: (optional) NX_FLOAT {units=NX_ENERGY}

The energy bandwidth or resolution of the crystal ...

The energy bandwidth or resolution of the crystal analyzer.

geometry_type: (optional) NX_CHAR

The type of crystal analyzer geometry. ...

The type of crystal analyzer geometry.

Any of these values: Johann | Johansson

diameter: (optional) NX_FLOAT {units=NX_LENGTH}

Diameter of the crystal analyzer wafer.

depends_on: (optional) NX_CHAR ⤆

Should point to the last transformation in the ...

Should point to the last transformation in the chain, i.e. transformations/analyzer_distance.

transformations: (optional) NXtransformations ⤆

Transformation chain placing the analyzer relative ...

Transformation chain placing the analyzer relative to the sample: azimuthal angle, polar angle, then distance.

analyzer_distance: (required) NX_NUMBER {units=NX_LENGTH} ⤆

Sample-to-analyzer distance.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: translation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [1, 0, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: analyzer_polar_angle

analyzer_polar_angle: (required) NX_NUMBER {units=NX_ANGLE} ⤆

Polar angle of the analyzer in the vertical ...

Polar angle of the analyzer in the vertical Rowland plane. Elevation from the horizontal beam plane to the sample-analyzer direction.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [0, -1, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: analyzer_azimuthal_angle

analyzer_azimuthal_angle: (required) NX_NUMBER {units=NX_ANGLE} ⤆

Azimuthal (horizontal) angle of the ...

Azimuthal (horizontal) angle of the spectrometer arm from the incident beam direction. Rotation around the vertical z-axis. Typically around 90 degrees to minimize elastic scattering.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [0, 0, 1]

@depends_on: (required) NX_CHAR ⤆

Should point to /entry/sample.

if: (recommended) NXdetector ⤆

Detector measuring the fluorescence intensity ...

Detector measuring the fluorescence intensity \(I_f\) diffracted by the crystal analyzer(s).

data: (required) NX_NUMBER (Rank: 1, Dimensions: [nEnergy]) ⤆

depends_on: (optional) NX_CHAR ⤆

Should point to the last transformation in the ...

Should point to the last transformation in the chain, i.e. transformations/if_distance.

transformations: (optional) NXtransformations ⤆

Transformation chain placing the detector relative ...

Transformation chain placing the detector relative to the sample: azimuthal angle, polar angle, then distance.

if_distance: (required) NX_NUMBER {units=NX_LENGTH} ⤆

Distance from the sample to the detector.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: translation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [1, 0, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: if_polar_angle

if_polar_angle: (required) NX_NUMBER {units=NX_ANGLE} ⤆

Polar angle of the detector in the vertical ...

Polar angle of the detector in the vertical Rowland plane.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [0, -1, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: if_azimuthal_angle

if_azimuthal_angle: (required) NX_NUMBER {units=NX_ANGLE} ⤆

Azimuthal (horizontal) angle of the detector ...

Azimuthal (horizontal) angle of the detector from the incident beam direction. Should match the analyzer azimuthal angle for on-Rowland focusing.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_NUMBER ⤆

Obligatory value: [0, 0, 1]

@depends_on: (required) NX_CHAR ⤆

Should point to /entry/sample.

PROCESS: (optional) NXprocess ⤆

Description of how :ref:`intensity ...

Description of how intensity was obtained from the raw detector data (i0, if).

program: (optional) NX_CHAR ⤆

Name of the program used for processing.

version: (optional) NX_CHAR ⤆

Version of the program used for processing.

date: (optional) NX_DATE_TIME ⤆

Date and time of processing.

Hypertext Anchors

List of hypertext anchors for all groups, fields, attributes, and links defined in this class.

NXDL Source:

https://github.com/nexusformat/definitions/blob/main/contributed_definitions/NXxas_herfd.nxdl.xml