ISO 23420:2021

INTERNATIONAL ISO
STANDARD 23420
First edition
2021-04
Microbeam analysis — Analytical
electron microscopy — Method for the
determination of energy resolution
for electron energy loss spectrum
analysis
Analyse par microfaisceaux — Microscopie électronique analytique
— Méthode de détermination de la résolution énergétique pour
l'analyse spectrale de la perte d'énergie des électrons
Reference number
©
ISO 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 3
5 Definition of the energy resolution . 5
6 Reference materials and energy determination . 5
6.1 General . 5
6.2 Materials selection for energy scale calibration . 5
6.3 Binding energy measurement of graphite in the XPS . 6
7 Measurement procedure and energy resolution determination . 6
7.1 General . 6
7.2 Predetermination of binding energy . 8
7.2.1 Obtain graphite and the other reference sample . 8
7.2.2 Measure C1s of graphite by using the XPS . 8
7.3 Setup of the S/TEM and the EELS, and sample setting . 8
7.4 First energy step, δE , calibration . 8
7.4.1 EELS acquisition set-up . 8
7.4.2 Determining the EELS first energy step, δE .
1 8
7.4.3 Acquisition of carbon K-edge EEL spectrum . 9
7.4.4 Calculate calibrated energy step δE .
1C 9
7.5 Measurement of peak close to the zero-loss peak, E , for the other reference
CZLP
sample using energy step δE .
1 12
7.5.1 EEL spectrum acquisition of the second reference sample using energy
step δE .
1 12
7.5.2 Obtain the value for CH between the zero-loss peak and the peak E .
2 CZLP 13
7.5.3 Calculate the peak E energy . .13
CZLP
7.6 Second energy step, δE , calibration .14
7.6.1 Determining the EELS second energy step, δE .
2 14
7.6.2 Acquire E EEL spectrum .15
CZLP
7.6.3 Obtain the value for CH between the zero-loss peak and peak E .
3 CZLP 15
7.6.4 Calculate calibrated energy step δE .
2C 15
7.7 Determining the calibrated EEL spectrometer energy resolution, ΔE .15
7.7.1 Acquisition of a ZLP EEL spectrum .15
7.7.2 Obtain the value for CH for the zero-loss peak .15
7.7.3 Calculate EEL spectrometer energy resolution, ΔE .15
7.8 Record items .16
8 Uncertainty for the measurement result of energy resolution .17
Annex A (informative) Example of measurement procedure for energy resolution
determination .18
Annex B (informative) Correspondence between energy values of XPS C1s and EELS carbon
K edge .26
Bibliography .28
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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electrotechnical standardization.
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This document was prepared by Technical Committee ISO/TC 202, Microbeam analysis, Subcommittee
SC 3, Analytical electron microscopy.
A list of all parts in the ISO 23420 series can be found on the ISO website.
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iv © ISO 2021 – All rights reserved

Introduction
In order to understand the chemical composition, the atomic bonding and the electronic structure,
electron energy loss analysis is often performed with the scanning transmission electron microscope
or the transmission electron microscope (S/TEM) equipped with the electron energy loss (EEL)
spectrometer.
In the analysis using EEL spectrometer system, the energy loss of incident electrons by the inelastic
interaction via phonon and plasmon excitations, intra- and inter-band transitions and the inner shell
ionization can be measured. The inner shell ionization is particularly useful and important as it gives
the information on chemical composition of materials. For the precise analysis based on the energy loss
peak decomposition and its energy shifts, it is vitally important to understand the energy resolution
of the EEL spectrometer system. However, the determination method of the energy resolution is not
standardized yet.
This document provides the procedures for energy step calibration and energy resolution determination
useful for the electron energy loss spectrum analysis in the S/TEM equipped with the EEL spectrometer.
INTERNATIONAL STANDARD ISO 23420:2021(E)
Microbeam analysis — Analytical electron microscopy —
Method for the determination of energy resolution for
electron energy loss spectrum analysis
1 Scope
This document specifies a determination procedure of energy resolution in the scanning transmission
electron microscope or the transmission electron microscope equipped with the electron energy loss
(EEL) spectrometer.
This document is applicable to both in-column type EEL spectrometer and post-column type EEL
spectrometer. These EEL signal detecting systems are applicable to a parallel detecting system and a
serial detecting system.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
beam diameter
full width at half maximum (FWHM) of the electron beam intensity profile for the STEM observation
3.2
Boersch effect
energy spread of electron beam due to Coulomb interaction (3.5) between electrons in the beam
3.3
channel
range of one pixel of the detector in the parallel detection (3.17) EELS
3.4
collection angle
EELS entrance aperture diameter divided by a camera length and a geometric factor (3.13) for the
STEM or the TEM diffraction mode, or EELS entrance aperture diameter divided by the distance from
crossover of the lens in front of the EEL spectrometer to the EELS entrance aperture for imaging mode
of the energy-filtering TEM
3.5
Coulomb interaction
repulsion of electrons by electric charge
3.6
detection plane
plane where energy dispersed electron focus
3.7
electron energy loss
energy shift of the electron kinetic energy due to the inelastic scattering in solids
3.8
energy dispersion
degree of change in position of the dispersed electrons at the detection plane (3.6) per unit energy change
3.9
energy resolution
FWHM of the zero-loss (3.21) peak
3.10
energy step
energy selecting window (3.11) per channel (3.3) in the parallel detection (3.17) EELS, or energy range
limited by the width of energy selecting slit in the serial detection (3.20) EELS
3.11
energy selecting window
energy range for selection of a specific energy loss value
3.12
entrance aperture
aperture for limiting the collection angle (3.4) of the EEL spectrometer
3.13
geometric factor
ratio of distance from a pro
...