2.3.3.3.179. NXprocess_mpes

Status:

base class, extends NXobject

Description:

:ref:`NXprocess_mpes` describes events of data processing, reconstruction, ...

NXprocess_mpes describes events of data processing, reconstruction, or analysis for photoemission-related data.

It extends the NXprocess class and provides a glossary of explicitly named processes and their metadata which are typical for photoemission data.

For now, the extension of NXprocess is performed by simply copying all existing groups, fields, and attibute from NXprocess. In the future, it is envisioned that this extension can be solved by base class inheritance.

Symbols:

No symbol table

Groups cited:

NXcalibration, NXdata, NXdistortion, NXelectron_level, NXnote, NXregistration

Structure:

@default: (optional) NX_CHAR

Declares which child group contains a path leading ...

Declares which child group contains a path leading to a NXdata group.

It is recommended (as of NIAC2014) to use this attribute to help define the path to the default dataset to be plotted. See https://www.nexusformat.org/2014_How_to_find_default_data.html

program: (optional) NX_CHAR

Name of the program used

sequence_index: (optional) NX_POSINT

Sequence index of processing, ...

Sequence index of processing, for determining the order of multiple NXprocess steps. Starts with 1.

version: (optional) NX_CHAR

Version of the program used

date: (optional) NX_DATE_TIME

Date and time of processing.

energy_calibration: (optional) NXcalibration

Calibration event on the energy axis. ...

Calibration event on the energy axis.

For XPS, the calibration should ideally be performed according to ISO 15472:2010 specification.

physical_quantity: (optional) NX_CHAR ⤆

Obligatory value: energy

calibrated_axis: (optional) NX_FLOAT {units=NX_ENERGY} ⤆

This is the calibrated energy axis to be used for data plotting.

kN_calibration: (optional) NXcalibration

Calibration event on a k-space axis. ...

Calibration event on a k-space axis.

It is envisioned that the individual calibrations for each coordinate are stored as kx_calibration, ky_calibration, kz_calibration, in accordance with the axis name definitions in NXdata_mpes.

It is also possible to have k_parallel_calibration and k_perp_calibration if the momentum axes are defined as k_parallel and k_perp for the parallel and perpendicular momenta, respectively.

physical_quantity: (optional) NX_CHAR ⤆

Obligatory value: momentum

calibrated_axis: (optional) NX_FLOAT {units=NX_WAVENUMBER} ⤆

This is the calibrated k-space axis to be used for data plotting.

angularN_calibration: (optional) NXcalibration

Calibration event of an angular axis. ...

Calibration event of an angular axis.

It is envisioned that the individual calibrations for each angle are stored as angular0_calibration, angular1_calibration, etc., in accordance with the axis name definitions in NXdata_mpes.

physical_quantity: (optional) NX_CHAR ⤆

Obligatory value: angle

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

This is the calibrated angular axis to be used for data plotting.

spatialN_calibration: (optional) NXcalibration

Calibration event of a spatial axis. ...

Calibration event of a spatial axis.

It is envisioned that the individual calibrations for each angle are stored as spatial0_calibration, spatial1_calibration, etc., in accordance with the axis name definitions in NXdata_mpes.

physical_quantity: (optional) NX_CHAR ⤆

Obligatory value: space

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

This is the calibrated spatial axis to be used for data plotting.

delay_calibration: (optional) NXcalibration

Calibration event of the delay time.

physical_quantity: (optional) NX_CHAR ⤆

Obligatory value: time

calibrated_axis: (optional) NX_FLOAT {units=NX_TIME} ⤆

This is the calibrated delay time axis to be used for data plotting.

polarization_angle_calibration: (optional) NXcalibration

Calibration event of the beam polarization angle.

physical_quantity: (optional) NX_CHAR ⤆

Obligatory value: beam polarization angle

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

This is the calibrated polarization angle axis to be used for data plotting.

ellipticity_calibration: (optional) NXcalibration

Calibration event of the ellipticity of the incoming or outgoing beam.

physical_quantity: (optional) NX_CHAR ⤆

Obligatory value: beam ellipticity

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

This is the calibrated ellipticity axis to be used for data plotting.

energy_referencing: (optional) NXcalibration

For energy referencing, the measured energies are corrected for the charging p ...

For energy referencing, the measured energies are corrected for the charging potential (i.e., the electrical potential of the surface region of an insulating sample, caused by irradiation) such that those energies correspond to a sample with no surface charge. Usually, the energy axis is adjusted by shifting all energies uniformally until one well-defined emission line peak (or the Fermi edge) is located at a known _correct_ energy.

This concept is related to term 12.74 ff. of the ISO 18115-1:2023 standard.

physical_quantity: (optional) NX_CHAR ⤆

Obligatory value: energy

reference_peak: (optional) NX_CHAR

Reference peak that was used for the calibration. ...

Reference peak that was used for the calibration.

For example: adventitious carbon | C-C | metallic Au | elemental Si | Fermi edge | vacuum level

binding_energy: (optional) NX_FLOAT {units=NX_ENERGY}

The binding energy (in units of eV) that the specified emission line appeare ...

The binding energy (in units of eV) that the specified emission line appeared at, after adjusting the binding energy scale.

This concept is related to term 12.16 of the ISO 18115-1:2023 standard.

offset: (optional) NX_FLOAT {units=NX_ENERGY} ⤆

Offset between measured binding energy and calibrated binding energy of the ...

Offset between measured binding energy and calibrated binding energy of the emission line.

calibrated_axis: (optional) NX_FLOAT {units=NX_ENERGY} ⤆

This is the calibrated energy axis to be used for data plotting. ...

This is the calibrated energy axis to be used for data plotting.

This should link to /entry/data/energy.

level: (optional) NXelectron_level

Electronic core or valence level that was used for the calibration.

transmission_correction: (optional) NXcalibration

In the transmission correction, each intensity measurement for electrons of a ...

In the transmission correction, each intensity measurement for electrons of a given kinetic energy is multiplied by the corresponding value in the relative_intensity field of the transmission_function. This calibration procedure is used to account for the different tranmsission efficiencies when using different lens modes.

transmission_function: (optional) NXdata ⤆

Transmission function of the electron analyser. ...

Transmission function of the electron analyser.

The transmission function (TF) specifies the detection efficiency for electrons of different kinetic energy passing through the electron analyser. This can be a link to /entry/instrument/electronanalyser/transmission_function.

@signal: (optional) NX_CHAR ⤆

Obligatory value: relative_intensity

@axes: (optional) NX_CHAR ⤆

Obligatory value: kinetic_energy

kinetic_energy: (optional) NX_FLOAT (Rank: 1, Dimensions: [n_transmission_function]) {units=NX_ENERGY}

Kinetic energy values

relative_intensity: (optional) NX_FLOAT (Rank: 1, Dimensions: [n_transmission_function]) {units=NX_UNITLESS}

Relative transmission efficiency for the given kinetic energies

REGISTRATION: (optional) NXregistration

Describes the operations of image registration

DISTORTION: (optional) NXdistortion

Describes the operations of image distortion correction

CALIBRATION: (optional) NXcalibration

Describes the operations of calibration procedures, e.g. axis calibrations.

NOTE: (optional) NXnote

The note will contain information about how the data was processed ...

The note will contain information about how the data was processed or anything about the data provenance. The contents of the note can be anything that the processing code can understand, or simple text.

The name will be numbered to allow for ordering of steps.

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/NXprocess_mpes.nxdl.xml