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Energy-Dispersive X-ray Spectroscopy (EDX)

Energy-Dispersive X-ray Spectroscopy is an elemental analysis technique typically coupled with electron microscopy (SEM/TEM). EDX identifies elements and their spatial distribution through characteristic X-ray emission.

Overview

This schema package defines:

  • EDXMeasurement - EDX measurements with elemental composition, spatial mapping, and quantification

EDX measurements extend BaseMeasurement, providing:

  • Links to measured samples and instrument
  • Electron beam parameters (voltage, current, spot size)
  • Detector configuration and acquisition settings
  • Elemental composition (atomic and weight percentages)
  • Spatial mapping data (element distribution)

Typical Usage

  1. Select samples: Reference samples or libraries to analyze
  2. Set beam conditions: Accelerating voltage (typically 10-20 kV), current, spot size
  3. Acquire spectrum: Collect X-ray counts vs. energy
  4. Identify elements: Peak identification and deconvolution
  5. Quantification: Calculate composition from peak intensities
  6. Mapping (optional): Scan beam to create elemental distribution maps

What EDX Tells You

  • Elemental composition: What elements are present and their concentrations
  • Spatial distribution: Element maps showing composition variations
  • Composition gradients: In combinatorial libraries, map composition space
  • Layer thickness: From cross-section analysis
  • Contamination: Identify unexpected elements
  • Stoichiometry: Compare to target compositions

EDX in Combinatorial Screening

For combinatorial libraries created by multi-target sputtering:

  1. Map intact library: Before cleaving, measure composition at multiple points
  2. Create gradient map: Interpolate composition across library
  3. Guide cleaving: Choose where to divide library for optimal sampling
  4. Verify samples: After cleaving, confirm compositions match predictions

Key Parameters

  • Accelerating voltage: Determines X-ray generation depth (higher V = deeper)
  • Beam current: Signal intensity vs. beam damage trade-off
  • Spot size: Spatial resolution vs. signal
  • Acquisition time: Counting statistics vs. measurement time
  • Working distance: Affects collection efficiency

EDX Limitations

  • Light elements: Poor sensitivity for Z < 11 (B, C, N, O challenging)
  • Spatial resolution: Typically 1-2 μm (limited by electron interaction volume)
  • Depth information: Averages over interaction depth (~1 μm)
  • Quantification accuracy: ±1-2 at% typical, depends on standards

EDX vs. XPS

  • EDX: Bulk analysis (~1 μm deep), better for heavy elements, spatial mapping
  • XPS: Surface analysis (~10 nm), better for light elements, chemical states

Schema Documentation

EDXQuantification

inherits from: nomad.datamodel.data.ArchiveSection

properties:

name type
element ['Ac', 'Ag', 'Al', 'Am', 'Ar', 'As', 'At', 'Au', 'B', 'Ba', 'Be', 'Bh', 'Bi', 'Bk', 'Br', 'C', 'Ca', 'Cd', 'Ce', 'Cf', 'Cl', 'Cm', 'Cn', 'Co', 'Cr', 'Cs', 'Cu', 'Db', 'Ds', 'Dy', 'Er', 'Es', 'Eu', 'F', 'Fe', 'Fl', 'Fm', 'Fr', 'Ga', 'Gd', 'Ge', 'H', 'He', 'Hf', 'Hg', 'Ho', 'Hs', 'I', 'In', 'Ir', 'K', 'Kr', 'La', 'Li', 'Lr', 'Lu', 'Lv', 'Mc', 'Md', 'Mg', 'Mn', 'Mo', 'Mt', 'N', 'Na', 'Nb', 'Nd', 'Ne', 'Nh', 'Ni', 'No', 'Np', 'O', 'Og', 'Os', 'P', 'Pa', 'Pb', 'Pd', 'Pm', 'Po', 'Pr', 'Pt', 'Pu', 'Ra', 'Rb', 'Re', 'Rf', 'Rg', 'Rh', 'Rn', 'Ru', 'S', 'Sb', 'Sc', 'Se', 'Sg', 'Si', 'Sm', 'Sn', 'Sr', 'Ta', 'Tb', 'Tc', 'Te', 'Th', 'Ti', 'Tl', 'Tm', 'Ts', 'U', 'V', 'W', 'Xe', 'Y', 'Yb', 'Zn', 'Zr'] The symbol of the element, e.g. 'Pb'.
atomic_fraction float64 The atomic fraction of the element.

EDXResult

inherits from: nomad_measurements.mapping.schema.MappingResult

properties:

name type
layer_thickness float64 The layer thickness from the EDX measurement.
unit=meter
assumed_material_density float64 The assumed material density for the thickness determination.
unit=kilogram / meter ** 3
electron_image str
quantifications EDXQuantification sub-section, repeats

normalization:

The normalizer for the EDXResult class.

Args: archive (EntryArchive): The archive containing the section that is being normalized. logger (BoundLogger): A structlog logger.

DTUSampleAlignment

inherits from: nomad_measurements.mapping.schema.RectangularSampleAlignment

properties:

name type
width float64 The width of the sample.
unit=meter, default=0.04
height float64 The height of the sample.
unit=meter, default=0.04

normalization:

The normalizer for the RectangularSampleAlignment class. Will calculate the affine transformation from the sample alignment.

Args: archive (EntryArchive): The archive containing the section that is being normalized. logger (BoundLogger): A structlog logger.

EDXMeasurement

inherits from: nomad_dtu_nanolab_plugin.schema_packages.basesections.DtuNanolabMeasurement, nomad.datamodel.metainfo.plot.PlotSection, nomad.datamodel.data.EntryData

properties:

name type
edx_data_file str The csv file containing the analysis of the EDX measurement using the LayerProbe software. Contains quantification results and alignment data.
electron_image_files str Data files containing the electron images. Images are automatically mapped to their respective spectra by extracting numbers from image filenames and matching them with the spectrum numbers from the 'Spectrum Label' column in the EDX data file (e.g., 'SE Image 1.png' matches 'Spectrum 1').
shape=['*']
native_file_zip str A zip archive containing the native data files from the EDX measurement.
avg_layer_thickness float64 The average layer thickness from the EDX measurement
unit=meter
avg_density float64 The assumed material density for the thickness determination
unit=kilogram / meter ** 3
results EDXResult The result of the measurement.
sub-section, repeats
sample_alignment DTUSampleAlignment The alignment of the sample.
sub-section

normalization:

The normalizer for the EDXMeasurement class.

Args: archive (EntryArchive): The archive containing the section that is being normalized. logger (BoundLogger): A structlog logger.