ASTM E1016-96(2002)
(Guide)Standard Guide for Literature Describing Properties of Electrostatic Electron Spectrometers
Standard Guide for Literature Describing Properties of Electrostatic Electron Spectrometers
SCOPE
1.1 The purpose of this guide is to familiarize the analyst with some of the relevant literature describing the physical properties of modern electrostatic electron spectrometers.
1.2 this guide is intended to apply to electron spectrometers generally used in Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS).
1.3 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.
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Designation:E1016–96 (Reapproved 2002)
Standard Guide for
Literature Describing Properties of Electrostatic Electron
Spectrometers
This standard is issued under the fixed designation E 1016; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 6. General Description of Electron Spectrometers
1.1 The purpose of this guide is to familiarize the analyst 6.1 An electron spectrometer is typically used to measure
with some of the relevant literature describing the physical the energy and angular distributions of electrons emitted from
properties of modern electrostatic electron spectrometers. a specimen, typically for energies in the range 0 to 2500 eV. In
1.2 Thisguideisintendedtoapplytoelectronspectrometers surface analysis applications, the analyzed electrons are pro-
generally used in Auger electron spectroscopy (AES) and duced from the bombardment of a sample surface with
X-ray photoelectron spectroscopy (XPS). electrons, photons or ions. The entire spectrometer instrument
1.3 This standard does not purport to address all of the may include one or more of the following: (1) apertures to
safety concerns, if any, associated with its use. It is the define the specimen area and emission solid angle for the
responsibility of the user of this standard to establish appro- electrons accepted for analysis; (2) an electrostatic and/or
priate safety and health practices and determine the applica- magnetic lens system; (3) an electrostatic (dispersing) ana-
bility of regulatory limitations prior to use. lyzer; and (4) a detector. Methods to check the operating
characteristics of X-ray photoelectron spectrometers are re-
2. Referenced Documents
ported in Practice E 902.
2.1 ASTM Standards:
6.2 Intensity Scale Calibration and Spectrometer Transmis-
E 673 Terminology Relating to Surface Analysis sion Function—Quantitative analysis requires the determina-
E 902 Practice for Checking the Operating Characteristics
tion of the ability of the spectrometer to transmit electrons, and
of X-Ray Photoelectron Spectrometers the resultant detector signal, throughout the spectrometer
E 1217 Practice for Determination of the Specimen Area
instrument. This can be described by an overall electron
Contributing to the Detected Signal in Auger Electron
energy-dependent transmission function Q (E) and is given by
Spectrometers and Some X-Ray Photoelectron Spectrom- the product (1,2), as follows:
eters
Q~E! 5 H~E!·T~E!·D~E!·F~E!, (1)
3. Terminology
where:
3.1 For definitions of terms used in this guide, refer to H(E) = the effect of mechanical imperfections (such as
aberrations, fringing fields, etc.),
Terminology E 673.
T(E) = electron-optical transmission function,
4. Summary of Guide
D(E) = detector efficiency, and
F(E) = efficiency of the counting systems.
4.1 This guide serves as a resource for relevant literature
Knowledge of this transmission function permits the cali-
which describes the properties of electron spectrometers com-
brationofthespectraintensityaxis(3).Adetailedreviewofthe
monly used in surface analysis.
experimental determination of the transmission function for
5. Significance and Use
XPS (4) and AES (5) measurements has been published.
6.3 Energy Scale Calibration—Quantitative analysis also
5.1 The analyst may use this document to obtain informa-
requires the absolute calibration of spectra energy scales in
tion on the properties of electron spectrometers and instrumen-
either XPS or AES. Suitable photon energy values for Al and
tal aspects associated with quantitative surface analysis.
Mg anode X-ray sources often used in XPS measurements are
available (6) and reference binding energy values for Cu, Au,
This guide is under the jurisdiction of ASTM Committee E42 on Surface
Analysis and is the direct responsibility of Subcommittee E42.03 onAuger Electron
Spectroscopy and XPS.
Current edition approved Sept. 10, 1996. Published November 1996. Originally
published as E 1016 – 84. Last previous edition E 1016 – 90. The boldface numbers in parentheses refer to the list of references at the end of
Annual Book of ASTM Standards, Vol 03.06. this guide.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E1016
andAg have been published (7). Binding energy scale calibra- 7.2 Apertures—Theeffectsofthespectrometerentranceand
tion procedures have been described in the literature for XPS exit slits and apertures, their associated fringing fields, as well
(8,9) and kinetic energy scale calibrations for AES (10-12) as the effect of the divergence of the incident electron trajec-
measurements. tories on analyzer performance, particularly energy resolution,
havealsobeenreviewed (13-17).Adetailedexaminationofthe
7. Literature
effects of unwanted internal scattering in CHA and CMA
7.1 ElectrostaticAnalyzers—Spectrometerscommonlyused
electron spectrometers has been reported in the literature
on modern AES and XPS spectrometer instruments generally
(19-21).
employ electrostatic deflection analyzers.Auger electron spec-
7.3 Lens Systems—Input lens systems are frequently em-
trometersoftenusecylindricalmirroranalyzer(CMA)designs,
ployed in CHA (and cylindrical sector) designs to vary the
although concentric hemispherical analyzers (CHA) (also
surface analysis area (22) and to permit a convenient location
known as spherical deflection (or sector) analyzers) are also
of the CHA so as to allow access of complementary surface
used.The CHAdesign is the most common analyzer employed
characterization techniques to the sample (23). The electro-
on modern XPS instruments, although double-pass CMA
staticlensdesignoftenconsistsofacoaxialseriesofelectrodes
designs were also employed on earlier XPS instruments.
that define the analysis area on the sample surface and
Retardingfieldanalyzers(RFA)havehistoricalinterestinearly
determines the electron trajectories at the input to the analyzer.
AESwork,butarenowcommonlyusedonlowenergyelectron
The lens system also determines the angular resolution and
diffraction apparatus.
modifies the transmission characteristics of the spectrometer
7.1.1 Electrostatic Deflection Analyzers— A review of the
system (1).Areview of electrostatic lens systems incorporated
general properties of deflection analyzers may be found in
in surface analysis instruments is offered (13-17,24). Lens
recentreviews(13,14).Amoredetailedreviewisalsoavailable
systems have also been introduced at the exit of analyzers for
where, in addition to the CMAand CHAdesigns, plane mirror,
photoelectron imaging (14,25-27). Methods to determine the
spherical mirror, cylindrical sector, and toroidal deflection
specimen area examined are described in Practice E 1217.
analyzers are treated (15-17). As the width of typical Auger
7.4 Detectors—Detection of the analyzed electrons is gen-
spectral features are several electron volts, the use of a CMA
erallyaccomplishedthroughtheuseofanelectronmultiplierto
design in conventional AES has sufficed for routine analysis,
produce usable signals. Surface analysis instruments currently
particularly for small area analysis where a compromise
use a variety of multipliers, but most are glass upon which a
between signal-to-noise and energy resolution is important.
resistive counting is placed. The coating is formulated to
These are commonly used at a resolution defined by the
provide a substantial secondary electron yield upon primary
full-width at half-maximum of the spectrometer energy reso-
electronimpact.Themultiplierhasapotentialplaceduponitso
lution, DE, divided by the electron energy, E, of 0.25 to 0.6 %.
that the secondary electrons are accelerated to adjacent coated
The ability to incorporate an electron source concentric with
surfaces, thus providing the electron multiplying effect. Mul-
the CMA axis has been extensively exploited in scanning-
tipliers are available in various shapes for both analog and
electron microscope instruments to give Auger data as a
pulse counting amplification modes of operation (28). Single-
function of beam position (that is, images). However, analysis
channel electron multipliers were common in early instru-
of the Auger spectra from some compounds and surface
ments, but multiple-channel (“multichannel”) electron multi-
morphologies may be enhanced by the use of a CHA design
pliers fabricated into thin plates are now available for use in
which can provide better energy resolution (but a lower
detectors. See a general review of electron multipliers (29-31).
transmission)andsuperiorangularresolution.TheCHAdesign
The use of position-sensitive detectors, such as resistive
is most frequently employed on XPS instruments where
anodes, as well as wedge and s
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