2.3.3.3.106. NXelectronanalyser¶
Status:
base class, extends NXobject
Description:
Basic class for describing a electron analyzer. ...
Basic class for describing a electron analyzer.
This concept is related to term 12.59 of the ISO 18115-1:2023 standard.
Symbols:
The symbols used in the schema to specify e.g. dimensions of arrays
nfa: Number of fast axes (axes acquired simultaneously, without scanning a physical quantity)
nsa: Number of slow axes (axes acquired scanning a physical quantity)
n_transmission_function: Number of data points in the transmission function.
- Groups cited:
NXcollectioncolumn, NXdata, NXdeflector, NXdetector, NXenergydispersion, NXfabrication, NXlens_em, NXresolution, NXspindispersion, NXtransformations
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 for a summary of the discussion.
description: (optional) NX_CHAR
Free text description of the type of the detector
name: (optional) NX_CHAR
work_function: (optional) NX_FLOAT {units=NX_ENERGY}
Work function of the electron analyser. ...
Work function of the electron analyser.
The work function of a uniform surface of a conductor is the minimum energy required to remove an electron from the interior of the solid to a vacuum level immediately outside the solid surface.
The kinetic energy \(E_K\) of a photoelectron emitted from an energy-level with binding energy \(E_B\) below the Fermi level is given by \(E_K = h\nu - E_B - W = h\nu - E_B - e \phi_{\mathrm{sample}}\). Here, \(W = e \phi_{\mathrm{sample}}\) is the work function of the sample surface (with the potential difference \(\phi_{\mathrm{sample}}\) between the electrochemical potential of electrons in the bulk and the electrostatic potential of an electron in the vacuum just outside the surface).
In PES measurements, the sample and the spectrometer (with work function \(\phi_{\mathrm{spectr.}}\)) are electrically connected and therefore their Fermi levels are aligned. Due to the difference in local vacuum level between the sample and spectrometer, there exists an electric potential difference (contact potential) \(\Delta\phi = \phi_{\mathrm{sample}} - \phi_{\mathrm{spectr.}}\). The measured kinetic energy of a photoelectron in PES is therefore given by \(E_K^{\mathrm{meas.}} = h\nu - E_B + \Delta \phi = h\nu - E_B - e \phi_{\mathrm{spectr.}}\). As a result, the measured kinetic energy \(E_K^{\mathrm{meas.}}\) of a photoelectron is independent of the sample work function. Nonetheless, the work function \(\phi_s\) needs to be known to accurately determine the binding energy scale.
voltage_energy_range: (optional) NX_FLOAT {units=NX_VOLTAGE}
Energy range of the voltage supplies. This influences the noise of the supplie ...
Energy range of the voltage supplies. This influences the noise of the supplies, and thereby the energy resolution.
fast_axes: (optional) NX_CHAR (Rank: 1, Dimensions: [nfa])
List of the axes that are acquired simultaneously by the detector. ...
List of the axes that are acquired simultaneously by the detector. These refer only to the experimental variables recorded by the electron analyser. Other variables such as temperature, manipulator angles etc. are labeled as fast or slow in the data.
¶ Mode
fast_axes
slow_axes
Hemispherical in ARPES mode
[‘energy’, ‘kx’]
Hemispherical with channeltron, sweeping energy mode
["energy"]
Tof
[‘energy’, ‘kx’, ‘ky’]
Momentum microscope, spin-resolved
[‘energy’, ‘kx’, ‘ky’]
[‘spin up-down’, ‘spin left-right’]
Axes may be less abstract than this, i.e. [‘detector_x’, ‘detector_y’]. If energy_scan_mode=sweep, fast_axes: [‘energy’, ‘kx’]; slow_axes: [‘energy’] is allowed.
slow_axes: (optional) NX_CHAR (Rank: 1, Dimensions: [nsa])
List of the axes that are acquired by scanning a physical parameter, listed in ...
List of the axes that are acquired by scanning a physical parameter, listed in order of decreasing speed. See fast_axes for examples.
depends_on: (optional) NX_CHAR
energy_resolution: (optional) NXresolution
Energy resolution of the analyser with the current setting. May be linked from ...
Energy resolution of the analyser with the current setting. May be linked from an NXcalibration.
physical_quantity: (optional) NX_CHAR ⤆
Obligatory value:
energy
resolution: (optional) NX_FLOAT {units=NX_ENERGY} ⤆
Minimum distinguishable energy separation in the energy spectra. ...
Minimum distinguishable energy separation in the energy spectra.
This concept is related to term 10.24 of the ISO 18115-1:2023 standard.
resolution_errors: (optional) NX_FLOAT {units=NX_ENERGY} ⤆
relative_resolution: (optional) NX_FLOAT ⤆
Ratio of the energy resolution of the electron analyser at a specified energ ...
Ratio of the energy resolution of the electron analyser at a specified energy value to that energy value.
This concept is related to term 10.7 of the ISO 18115-1:2023 standard.
momentum_resolution: (optional) NXresolution
Momentum resolution of the electron analyser (FWHM)
physical_quantity: (optional) NX_CHAR ⤆
Obligatory value:
momentum
resolution: (optional) NX_FLOAT {units=NX_WAVENUMBER} ⤆
resolution_errors: (optional) NX_FLOAT {units=NX_WAVENUMBER} ⤆
angular_resolution: (optional) NXresolution
spatial_resolution: (optional) NXresolution
Spatial resolution of the electron analyser (Airy disk radius) ...
Spatial resolution of the electron analyser (Airy disk radius)
This concept is related to term 10.14 of the ISO 18115-1:2023 standard.
physical_quantity: (optional) NX_CHAR ⤆
Obligatory value:
length
transmission_function: (optional) NXdata
Transmission function of the electron analyser. ...
Transmission function of the electron analyser.
The transmission function (TF) specifies the detection efficiency per solid angle for electrons of different kinetic energy passing through the electron analyser. It depends on the spectrometer geometry as well as operation settings such as lens mode and pass energy. The transmission function is usually given as relative intensity vs. kinetic energy.
The TF is used for calibration of the intensity scale in quantitative XPS. Without proper transmission correction, a comparison of results measured from the same sample using different operating modes for an instrument would show significant variations in atomic concentrations.
This concept is related to term 7.15 of the ISO 18115-1:2023 standard.
Obligatory value:
relative_intensity
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
TRANSFORMATIONS: (optional) NXtransformations
Collection of axis-based translations and rotations to describe the location a ...
Collection of axis-based translations and rotations to describe the location and geometry of the electron analyser as a component in the instrument. Conventions from the NXtransformations base class are used. In principle, the McStas coordinate system is used. The first transformation has to point either to another component of the system or “.” (for pointing to the reference frame) to relate it relative to the experimental setup. Typically, the components of a system should all be related relative to each other and only one component should relate to the reference coordinate system.
COLLECTIONCOLUMN: (optional) NXcollectioncolumn
Describes the electron collection (spatial and momentum imaging) column
ENERGYDISPERSION: (optional) NXenergydispersion
Describes the energy dispersion section
SPINDISPERSION: (optional) NXspindispersion
Describes the spin dispersion section
DETECTOR: (optional) NXdetector
Describes the electron detector
DEFLECTOR: (optional) NXdeflector
Deflectors outside the main optics ensembles described by the subclasses
LENS_EM: (optional) NXlens_em
Individual lenses outside the main optics ensembles described by the subclasses
FABRICATION: (optional) NXfabrication
RESOLUTION: (optional) NXresolution
Any other resolution not explicitly named in this base class.
Hypertext Anchors¶
List of hypertext anchors for all groups, fields, attributes, and links defined in this class.
/NXelectronanalyser/angular_resolution/physical_quantity-field
/NXelectronanalyser/angular_resolution/resolution_errors-field
/NXelectronanalyser/energy_resolution/physical_quantity-field
/NXelectronanalyser/energy_resolution/relative_resolution-field
/NXelectronanalyser/energy_resolution/resolution_errors-field
/NXelectronanalyser/momentum_resolution/physical_quantity-field
/NXelectronanalyser/momentum_resolution/resolution_errors-field
/NXelectronanalyser/spatial_resolution/physical_quantity-field
/NXelectronanalyser/spatial_resolution/resolution_errors-field
/NXelectronanalyser/transmission_function/kinetic_energy-field
/NXelectronanalyser/transmission_function/relative_intensity-field