2.3.3.3.210. NXxps

Status:

application definition, extends NXmpes

Description:

This is the application definition for X-ray photoelectron spectroscopy.

Symbols:

No symbol table

Groups cited:

NXbeam, NXcalibration, NXcollectioncolumn, NXcoordinate_system_set, NXcoordinate_system, NXdata, NXelectronanalyser, NXenergydispersion, NXentry, NXfit_background, NXfit_function, NXfit_parameter, NXfit, NXinstrument, NXpeak, NXprocess_mpes, NXsample, NXsource, NXtransformations

Structure:

ENTRY: (required) NXentry ⤆

definition: (required) NX_CHAR ⤆

Obligatory value: NXxps

method: (required) NX_CHAR ⤆

A name of the experimental method according to `Clause 11`_ of ...

A name of the experimental method according to Clause 11 of the ISO 18115-1:2023 specification.

Examples for XPS-related experiments include:

  • X-ray photoelectron spectroscopy (XPS)

  • angle-resolved X-ray photoelectron spectroscopy (ARXPS)

  • ultraviolet photoelectron spectroscopy (UPS)

  • hard X-ray photoemission spectroscopy (HAXPES)

  • near ambient pressure X-ray photoelectron spectroscopy (NAPXPS)

  • electron spectroscopy for chemical analysis (ESCA)

geometries: (recommended) NXcoordinate_system_set ⤆

xps_coordinate_system: (optional) NXcoordinate_system ⤆

In traditional surface science, a left-handed coordinate system is used su ...

In traditional surface science, a left-handed coordinate system is used such that the positive z-axis points along the normal of the sample stage, and the x- and y-axes lie in the plane of the sample stage. However, in NeXus, a coordinate system that is the same as McStas is used. xps_coordinate_system gives the user the opportunity to work in the traditional base coordinate system.

../../_images/xps_cs.png

origin: (required) NX_CHAR ⤆

Obligatory value: sample stage

handedness: (required) NX_CHAR ⤆

Obligatory value: left_handed

z_direction: (required) NX_CHAR ⤆

Obligatory value: sample stage normal

x: (required) NX_CHAR

Obligatory value: [-1, 0, 0]

y: (required) NX_CHAR

Obligatory value: [0, 1, 0]

z: (required) NX_CHAR

Obligatory value: [0, 0, 1]

depends_on: (required) NX_CHAR ⤆

Link to transformations defining the XPS base coordinate system, ...

Link to transformations defining the XPS base coordinate system, which is defined such that the positive z-axis points along the sample stage normal, and the x- and y-axes lie in the plane of the sample stage.

coordinate_system_transformations: (optional) NXtransformations ⤆

Set of transformations, describing the orientation of the XPS coordinate ...

Set of transformations, describing the orientation of the XPS coordinate system with respect to the beam coordinate system (.) or any other coordinate system.

The transformations in coordinate_system_transformations depend on the actual instrument geometry. If the z-axis is pointing in the direction of gravity (i.e., if the sample is mounted horizontally), the following transformations can be used for describing the XPS coordinate system with respect to the beam coordinate system (.):

xps_coordinate_system:NXcoordinate_system
  depends_on=entry/geometries/xps_coordinate_system/coordinate_transformations/z_rotation
  coordinate_system_transformations:NXtransformations
    z_rotation=beam_azimuth_angle
      @depends_on=y_flip
      @transformation_type=rotation
      @vector=[0, 0, 1]
      @units=degree
    y_flip=180
      @depends_on=y_rotation
      @transformation_type=rotation
      @vector=[0, 1, 0]
      @units=degree
    y_rotation=beam_polar_angle_of_incidence
      @depends_on=.
      @transformation_type=rotation
      @vector=[0, 1, 0]
      @units=degree

INSTRUMENT: (required) NXinstrument ⤆

Description of the XPS spectrometer and its individual parts. ...

Description of the XPS spectrometer and its individual parts.

This concept is related to term 12.58 of the ISO 18115-1:2023 standard.

sourceTYPE: (recommended) NXsource ⤆

power: (recommended) NX_FLOAT {units=NX_POWER} ⤆

beamTYPE: (required) NXbeam ⤆

depends_on: (recommended) NX_CHAR ⤆

Reference to the transformation describing the orientation of the beam ...

Reference to the transformation describing the orientation of the beam relative to a defined coordinate system.

transformations: (recommended) NXtransformations ⤆

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

Incidence angle of the beam with respect to the upward z-direction, de ...

Incidence angle of the beam with respect to the upward z-direction, defined by the sample stage.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_CHAR

Obligatory value: [0, -1, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: beam_azimuth_angle

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

Azimuthal rotation of the beam from the y-direction towards the operat ...

Azimuthal rotation of the beam from the y-direction towards the operator, defined by the sample stage.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_CHAR

Obligatory value: [0, 0, -1]

@depends_on: (required) NX_CHAR ⤆

This should point to the last element of the coordinate system trans ...

This should point to the last element of the coordinate system transformations defined in /entry/geometries/xps_coordinate_system/coordinate_system_transformations.

ELECTRONANALYSER: (required) NXelectronanalyser ⤆

work_function: (required) NX_FLOAT ⤆

depends_on: (recommended) NX_CHAR ⤆

Reference to the transformation describing the orientation of the analyz ...

Reference to the transformation describing the orientation of the analyzer relative to a defined coordinate system.

transmission_function: (recommended) NXdata ⤆

COLLECTIONCOLUMN: (required) NXcollectioncolumn ⤆

magnification: (recommended) NX_FLOAT {units=NX_DIMENSIONLESS} ⤆

ENERGYDISPERSION: (required) NXenergydispersion ⤆

radius: (recommended) NX_NUMBER {units=NX_LENGTH}

energy_scan_mode: (required) NX_CHAR ⤆

transformations: (recommended) NXtransformations ⤆

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

Polar tilt of the analyser with respect to the upward z-direction, def ...

Polar tilt of the analyser with respect to the upward z-direction, defined by the sample stage.

The angle between the incoming beam and the analyser is given by beam_analyser_angle = beam_polar_angle_of_incidence + analyser_take_off_polar_angle. In practice, the analyser axis is often set as the z axis (analyser_take_off_polar_angle = 0), so that beam_analyser_angle = beam_polar_angle_of_incidence. For magic angle configurations, this angle is 54.5°.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_CHAR

Obligatory value: [0, -1, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: analyser_take_off_azimuth_angle

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

Azimuthal rotation of the analyser from the y-direction towards the op ...

Azimuthal rotation of the analyser from the y-direction towards the operator, defined by the sample stage.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_CHAR

Obligatory value: [0, 0, -1]

@depends_on: (required) NX_CHAR ⤆

This should point to the last element of the coordinate system trans ...

This should point to the last element of the coordinate system transformations defined in /entry/geometries/xps_coordinate_system/coordinate_system_transformations.

PROCESS_MPES: (required) NXprocess_mpes ⤆

energy_referencing: (recommended) NXcalibration ⤆

transmission_correction: (recommended) NXcalibration ⤆

SAMPLE: (required) NXsample ⤆

depends_on: (recommended) NX_CHAR ⤆

Reference to the transformation describing the orientation of the sample ...

Reference to the transformation describing the orientation of the sample relative to a defined coordinate system.

transformations: (recommended) NXtransformations ⤆

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

Clockwise rotation about the sample normal.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_CHAR

Obligatory value: [0, 0, -1]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: sample_normal_polar_angle_of_tilt

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

Polar tilt of the sample with respect to the upward z-direction, defined ...

Polar tilt of the sample with respect to the upward z-direction, defined by the sample stage.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_CHAR

Obligatory value: [0, -1, 0]

@depends_on: (required) NX_CHAR ⤆

Obligatory value: sample_normal_tilt_azimuth_angle

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

Azimuthal rotation of the sample from the y-direction towards the operat ...

Azimuthal rotation of the sample from the y-direction towards the operator, defined by the sample stage.

@transformation_type: (required) NX_CHAR ⤆

Obligatory value: rotation

@vector: (required) NX_CHAR

Obligatory value: [0, 0, -1]

@depends_on: (required) NX_CHAR ⤆

This should point to the last element of the coordinate system transfo ...

This should point to the last element of the coordinate system transformations defined in /entry/geometries/xps_coordinate_system/coordinate_system_transformations.

data: (required) NXdata ⤆

@energy_indices: (required) NX_CHAR ⤆

energy: (required) NX_NUMBER ⤆

@reference: (recommended) NX_CHAR ⤆

FIT: (recommended) NXfit

Peak model for XPS fitting. Each `NXfit` instance shall be used for the desc ...

Peak model for XPS fitting. Each NXfit instance shall be used for the description of _one_ peak fit in _one_ XPS region. As an example, this could be used to describe the fitting of one measured C 1s spectrum.

This concept is related to term 3.29 of the ISO 18115-1:2023 standard.

label: (required) NX_CHAR ⤆

figure_of_meritMETRIC: (recommended) NX_NUMBER ⤆

@metric: (required) NX_CHAR ⤆

data: (required) NXdata ⤆

Input data and results of the fit.

input_dependent: (required) NX_NUMBER {units=NX_ANY} ⤆

Dependent variable for this fit procedure. ...

Dependent variable for this fit procedure.

This could be a link to entry/data/data.

input_independent: (required) NX_NUMBER {units=NX_ANY} ⤆

Independent variable for this fit procedure. ...

Independent variable for this fit procedure.

This could be a link to entry/data/energy.

envelope: (required) NX_NUMBER ⤆

residual: (recommended) NX_NUMBER ⤆

peakPEAK: (required) NXpeak ⤆

label: (required) NX_CHAR ⤆

total_area: (recommended) NX_CHAR

Total area under the peak after background removal. ...

Total area under the peak after background removal.

This concept is related to term 3.16 of the ISO 18115-1:2023 standard.

relative_atomic_concentration: (optional) NX_FLOAT {units=NX_ANY}

Atomic concentration of the species defined by this peak. This should be ...

Atomic concentration of the species defined by this peak. This should be a value between 0 and 1.

data: (required) NXdata ⤆

position: (required) NX_NUMBER {units=NX_ENERGY} ⤆

This could be a link to entry/data/energy.

intensity: (required) NX_NUMBER ⤆

Intensity values of the fitted function at each energy in the position ...

Intensity values of the fitted function at each energy in the position field.

This concept is related to term 3.15 of the ISO 18115-1:2023 standard.

function: (recommended) NXfit_function ⤆

description: (required) NX_CHAR ⤆

formula: (recommended) NX_CHAR ⤆

area: (optional) NXfit_parameter ⤆

Area of the peak.

width: (optional) NXfit_parameter ⤆

Width of a peak at a defined fraction of the peak height. ...

Width of a peak at a defined fraction of the peak height.

Usually, this will be the Full Width at Half Maximum of the peak (FWHM). For asymmetric peaks, convenient measures of peak width are the half-widths of each side of the peak at half maximum intensity.

This concept is related to term 3.28 of the ISO 18115-1:2023 standard.

value: (required) NX_CHAR {units=NX_ENERGY}

position: (optional) NXfit_parameter ⤆

Position of the peak on the energy axis.

value: (required) NX_CHAR {units=NX_ENERGY}

backgroundBACKGROUND: (required) NXfit_background ⤆

Functional form of the fitted XPS background. ...

Functional form of the fitted XPS background.

This concept is related to term 3.21 of the ISO 18115-1:2023 standard.

label: (recommended) NX_CHAR ⤆

data: (required) NXdata ⤆

position: (required) NX_NUMBER {units=NX_ENERGY} ⤆

intensity: (required) NX_NUMBER ⤆

function: (recommended) NXfit_function ⤆

description: (required) NX_CHAR ⤆

Human-readable description of the background fit function. ...

Human-readable description of the background fit function.

Examples for background descriptions

Background Type

Description

Linear

Linear background, i.e., a simple straight line from the minimal to the maximal abscissa value.

Shirley

Shirley background. In the Shirley background, the background intensity at any given binding energy is proportional to the intensity of the total peak area above the background in the lower binding energy peak range (i.e., the background goes up in proportion to the total number of photoelectrons below its binding energy position).

Tougaard

Tougaard background (or Tougaard universal cross-section approach) which is a methodology for integrating the intensity of the background at a given binding energy from the spectral intensities to higher kinetic energies.

Step Down/Step Up

Background function for fitting a complementary error function to an edge, used for fitting a step in the data.

In case none of these examples apply, the functional form of the background should be given by the formula field.

formula: (recommended) NX_CHAR ⤆

global_fit_function: (recommended) NXfit_function ⤆

description: (recommended) NX_CHAR ⤆

formula: (recommended) NX_CHAR ⤆

error_function: (recommended) NXfit_function ⤆

description: (recommended) NX_CHAR ⤆

formula: (recommended) NX_CHAR ⤆

Hypertext Anchors

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

NXDL Source:

https://github.com/FAIRmat-NFDI/nexus_definitions/tree/fairmat/contributed_definitions/NXxps.nxdl.xml