ASTM E1523-09
(Guide)Standard Guide to Charge Control and Charge Referencing Techniques in X-Ray Photoelectron Spectroscopy
Standard Guide to Charge Control and Charge Referencing Techniques in X-Ray Photoelectron Spectroscopy
SIGNIFICANCE AND USE
The acquisition of chemical information from variations in the energy position of peaks in the XPS spectrum is of primary interest in the use of XPS as a surface analytical tool. Surface charging acts to shift spectral peaks independent of their chemical relationship to other elements on the same surface. The desire to eliminate the influence of surface charging on the peak positions and peak shapes has resulted in the development of several empirical methods designed to assist in the interpretation of the XPS peak positions, determine surface chemistry, and allow comparison of spectra of conducting and non-conducting systems of the same element. It is assumed that the spectrometer is generally working properly for non-insulating specimens (see Practice E 902).
Although highly reliable methods have now been developed to stabilize surface potentials during XPS analysis of most materials (5, 6), no single method has been developed to deal with surface charging in all circumstances (10, 11). For insulators, an appropriate choice of any control or referencing system will depend on the nature of the specimen, the instruments, and the information needed. The appropriate use of charge control and referencing techniques will result in more consistent, reproducible data. Researchers are strongly urged to report both the control and referencing techniques that have been used, the specific peaks and binding energies used as standards (if any), and the criteria applied in determining optimum results so that the appropriate comparisons may be made.
SCOPE
1.1 This guide acquaints the X-ray photoelectron spectroscopy (XPS) user with the various charge control and charge shift referencing techniques that are and have been used in the acquisition and interpretation of XPS data from surfaces of insulating specimens and provides information needed for reporting the methods used to customers or in the literature.
1.2 This guide is intended to apply to charge control and charge referencing techniques in XPS and is not necessarily applicable to electron-excited systems.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1523 − 09
StandardGuide to
Charge Control and Charge Referencing Techniques in
1
X-Ray Photoelectron Spectroscopy
This standard is issued under the fixed designation E1523; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
3.1 Definitions—See Terminology E673 for definitions of
1.1 This guide acquaints the X-ray photoelectron spectros-
copy (XPS) user with the various charge control and charge terms used in XPS.
shift referencing techniques that are and have been used in the
3.2 Symbols:
acquisition and interpretation of XPS data from surfaces of
BE Binding energy, in eV
insulating specimens and provides information needed for
BE Corrected binding energy, in eV
corr
BE Measured binding energy, in eV
reporting the methods used to customers or in the literature.
meas
BE Reference binding energy, in eV
ref
1.2 This guide is intended to apply to charge control and BE Measured Binding energy, in eV, of a reference line
meas, ref
FWHM Full width at half maximum amplitude of a peak in the
charge referencing techniques in XPS and is not necessarily
photoelectron spectrum above the background, in eV
applicable to electron-excited systems.
XPS X-ray photoelectron spectroscopy
∆ Correction energy, to be added to measured binding
corr
1.3 The values stated in SI units are to be regarded as
energies for charge correction, in eV
standard. No other units of measurement are included in this
standard.
4. Overview of Charging Effects
1.4 This standard does not purport to address all of the
4.1 For insulating specimen surfaces, the emission of pho-
safety concerns, if any, associated with its use. It is the
toelectrons following X-ray excitation may result in a tempo-
responsibility of the user of this standard to establish appro-
rary (or sometimes persistent) buildup of a positive surface
priate safety and health practices and determine the applica-
charge caused by the photoelectric effect. Its insulating nature
bility of regulatory limitations prior to use.
prevents the compensation of the charge buildup by means of
electron conduction from the sample holder. This positive
2. Referenced Documents surface charge changes the surface potential thereby shifting
2
the measured energies of the photoelectron peaks to higher
2.1 ASTM Standards:
binding energy. This binding energy shift may reach a nearly
E673 Terminology Relating to SurfaceAnalysis (Withdrawn
3
steady-state value of between 2 and 5 eV for spectrometers
2012)
equipped with nonmonochromatic X-ray sources. The surface
E902 Practice for Checking the Operating Characteristics of
3
potential charge and the resulting binding energy shift is,
X-Ray Photoelectron Spectrometers (Withdrawn 2011)
generally, larger for spectrometers equipped with monochro-
E1078 Guide for Specimen Preparation and Mounting in
matic X-ray sources because of the, generally, lower flux of
Surface Analysis
low-energy electrons impinging on the specimen surface. This
E1829 Guide for Handling Specimens Prior to Surface
lower flux arises because focused, monochromatic X-ray
Analysis
beams irradiate only a portion of the specimen and not other
nearby surfaces (for example, the specimen holder) that are
sources of low-energy electrons. The absence of an X-ray
1
This guide is under the jurisdiction of ASTM Committee E42 on Surface
window in many monochromatic X-ray sources (or a greater
Analysis and is the direct responsibility of Subcommittee E42.03 on Auger Electron
distance of the specimen from the X-ray window) also elimi-
Spectroscopy and X-Ray Photoelectron Spectroscopy.
nates another source of low-energy electrons.
Current edition approved May 1, 2009. Published June 2009. Originally
approved in 1993. Last previous edition approved in 2003 as E1523 – 03. DOI:
4.2 The amount of induced surface charge, its distribution
10.1520/E1523-09.
2
acrossthespecimensurface,anditsdependenceonexperimen-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
tal conditions are determined by several factors including
Standards volume information, refer to the standard’s Document Summary page on
specimen composition, homogeneity, magnitude of surface
the ASTM website.
3
conductivity, total photoionization cross-section, surface
The last approved version of this historical standard is referenced on
www.astm.org. topography, spatial distribution of the exciting X-rays, and
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United Stat
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:E1523–03 Designation:E1523–09
Standard Guide to
Charge Control and Charge Referencing Techniques in
1
X-Ray Photoelectron Spectroscopy
This standard is issued under the fixed designation E1523; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This guide acquaints the X-ray photoelectron spectroscopy (XPS) user with the various charge control and charge shift
referencing techniques that are and have been used in the acquisition and interpretation of X-ray photoelectron spectroscopy
(XPS)XPS data from surfaces of insulating specimens and provides information needed for reporting the methods used to
customers or in the literature.
1.2 ThisguideisintendedtoapplytochargecontrolandchargereferencingtechniquesinXPSandisnotnecessarilyapplicable
to electron-excited systems.
1.3SI units are standard unless otherwise noted.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
E673 Terminology Relating to Surface Analysis
E902 Practice for Checking the Operating Characteristics of X-Ray Photoelectron Spectrometers
E1078 Guide for Specimen Handling inAuger Electron Spectroscopy, X-Ray Photoelectron Spectroscopy, and Secondary Ion
2
Mass Spectrometry Guide for Specimen Preparation and Mounting in Surface Analysis
2
E1829 Guide for Specimen Preparation and Mounting in Surface Analysis Guide for Handling Specimens Prior to Surface
Analysis
3. Terminology
3.1Definitions:
3.1.1See Terminology E673 for definitions of terms used in X-ray photoelectron spectroscopy.
3.1.2Symbols
3.1 Definitions—See Terminology E673 for definitions of terms used in XPS.
3.2 Symbols:
BE Binding energy, in eV
BE Corrected binding energy, in eV
corr
BE Measured binding energy, in eV
meas
BE Reference binding energy, in eV
ref
BE Measured Binding energy, in eV, of a reference line
meas, ref
FWHM Full width at half maximum amplitude of a peak in the photoelectron
spectrum above the background, in eV
XPS X-ray photoelectron spectroscopy
D Correction energy, to be added to measured binding energies for
corr
charge correction, in eV
1
This guide is under the jurisdiction of ASTM Committee E42 on Surface Analysis and is the direct responsibility of Subcommittee E42.03 on Auger Electron
Spectroscopy and X-ray Photoelectron Spectroscopy.
Current edition approved May 10, 2003. Published July 2003. Originally approved in 1993. Last previous edition approved in 1997 as E 1523 – 97.on Auger Electron
Spectroscopy and X-Ray Photoelectron Spectroscopy.
Current edition approved May 1, 2009. Published June 2009. Originally approved in 1993. Last previous edition approved in 2003 as E1523–03.
2
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book of ASTM Standards
, Vol 03.06.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
---------------------- Page: 1 ----------------------
E1523–09
4. Overview of Charging Effects
4.1 For insulating specimen surfaces, the emission of photoelectrons following X-ray excitation may result in a temporary (or
sometimes persistent) buildup of a positive surface charge caused by the photoelectric effect. Its insulating nature prevents the
compensationofthechargebuildupbymeansofelectronconductionfromthesampleholder.Thispositivesurfacechargechanges
the surface potential thereby shifting the measured energies of the photoelectron peaks to higher binding energy. This binding
energy shift may reach a nearly steady-state value of between 2 and 5eV for spectrometers equipped with nonmonochromatic
X-ray sources. The surface potential charge and the resulting binding energy shift is, generally, larger for spectrometers equipped
with monochromatic X-ray sources because of the, generally, lower flux of low-energy electrons impi
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.