1、Designation: E2108 10E2108 16Standard Practice forCalibration of the Electron Binding-Energy Scale of anX-Ray Photoelectron Spectrometer1This standard is issued under the fixed designation E2108; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes a procedure for calibrating the electron binding-energy (BE) scale of
3、 an X-ray photoelectronspectrometer that is to be used for performing spectroscopic analysis of photoelectrons excited by unmonochromated aluminumor magnesium K X-rays or by monochromated aluminum K X-rays.1.2 The calibration of the BE scale is recommended after the instrument is installed or modifi
4、ed in any substantive way.Additional checks and, if necessary, recalibrations are recommended at intervals chosen to ensure that BE measurements arestatistically unlikely to be made with an uncertainty greater than a tolerance limit, specified by the analyst, based on theinstrumental stability and t
5、he analystsanalysts needs. Information is provided by which the analyst can select an appropriatetolerance limit for the BE measurements and the frequency of calibration checks.1.3 This practice is based on the assumption that the BE scale of the spectrometer is sufficiently close to linear to allow
6、 forcalibration by measurements of reference photoelectron lines having BEs near the extremes of the working BE scale. In mostcommercial instruments, X-ray sources with aluminum or magnesium anodes are employed and BEs are typically measured at leastover the 0100001200 eV range. This practice can be
7、 used for the BE range from 0 eV to 1040 eV.1.4 The assumption that the BE scale is linear is checked by a measurement made with a reference photoelectron line orAuger-electron line that appears at an intermediate position. A single check is a necessary but not sufficient condition forestablishing l
8、inearity of the BE scale. Additional checks can be made with specified reference lines on instruments equipped withmagnesium or unmonochromated aluminum X-ray sources, with secondary BE standards, or by following the procedures of theinstrument manufacturer. Deviations from BE-scale linearity can oc
9、cur because of mechanical misalignments, excessive magneticfields in the region of the analyzer, or imperfections or malfunctions in the power supplies. This practice does not check for, noridentify, problems of this type.type but simply verifies the linearity of the BE scale.1.5 After an initial ch
10、eck of the BE-scale linearity and measurements of the repeatability standard deviation for the maincalibration lines for a particular instrument, a simplified procedure is given for routine checks of the calibration at subsequenttimes.1.6 This practice is recommended for use with X-ray photoelectron
11、 spectrometers operated in the constant-pass-energy orfixed-analyzer-transmission mode and for which the pass energy is less than 200 eV; otherwise, depending on the configurationof the instrument, a relativistic equation could be needed for the calibration. The practice should not be used for instr
12、umentsoperated in the constant-retardation-ratio mode at retardation ratios less than 10, for instruments with an energy resolution above1.5 eV, or in applications for which BE measurements are desired with tolerance limits of 60.03 eV or less.1.7 On instruments equipped with a monochromated aluminu
13、m K X-ray source, a measurement of the position of a specifiedAuger-electron line can be used, if desired, to determine the average energy of the X-rays incident on the specimen. Thisinformation is needed for the determination of modified Auger parameters.1.8 The values stated in SI units are to be
14、regarded as standard. No other units of measurement are included in this standard.1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and d
15、etermine the applicability of regulatorylimitations prior to use.1 This practice is under the jurisdiction of ASTM Committee E42 on Surface Analysis and is the direct responsibility of Subcommittee E42.03 on Auger ElectronSpectroscopy and X-Ray Photoelectron Spectroscopy.Current edition approved Nov
16、. 1, 2010Nov. 1, 2016. Published December 2010December 2016. Originally approved in 2000. Last previous edition approved in 20052010as E2108 05.E2108 10. DOI: 10.1520/E2108-10.10.1520/E2108-16.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indic
17、ation of what changes have been made to the previous version. Becauseit 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 versionof the standard as published by ASTM is to be co
18、nsidered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Documents2.1 ASTM Standards:2E456 Terminology Relating to Quality and StatisticsE673 Terminology Relating to Surface Analysis (Withdrawn 2012
19、)3E902 Practice for Checking the Operating Characteristics of X-Ray Photoelectron Spectrometers (Withdrawn 2011)3E1016 Guide for Literature Describing Properties of Electrostatic Electron SpectrometersE1078 Guide for Specimen Preparation and Mounting in Surface AnalysisE1523 Guide to Charge Control
20、and Charge Referencing Techniques in X-Ray Photoelectron Spectroscopy2.2 ISO Standards:4ISO 9001:20009001:2015 Quality Management SystemsRequirements management systemsRequirementsISO 15472:200115472:2010 Surface Chemical AnalysisX-Ray Photoelectron SpectrometersCalibration of Energy Scale-schemical
21、 analysisX-ray photoelectron spectrometersCalibration of energy scalesISO 18115:200118115-1:2013 Surface Chemical AnalysisVocabulary chemical analysisVocabularyPart 1: General termsand terms used in spectroscopy3. Terminology3.1 DefinitionsFor definitions ofSince Terminology E673 terms used in X-ray
22、 photoelectron spectroscopy and surfaceanalysis, see Terminologywas withdrawn in 2012, definitions of terms used in Auger and E673 and ISO 18115:2001.X-rayphotoelectron spectroscopy are now based on ISO 18115-1:2013.5 For definitions of terms used in statistics, see TerminologyE456.3.2 Symbols and A
23、bbreviationsTable 1 shows definitions of the symbols and abbreviations used in this practice.4. Summary of Practice4.1 A procedure is given for calibrating the BE scale of an X-ray photoelectron spectrometer equipped with one or more of thefollowing sources of characteristic K X-rays: magnesium (Mg)
24、 source; unmonochromated aluminum (Al) source; ormonochromated Al source. This procedure is based on ISO 15472:2001.15472:2010. In a first calibration for particular operatingconditions of the instrument, or after the instrument has been modified, measurements are made of the BEs of specified core l
25、evelsof copper and gold, and these values are then compared with corresponding reference energies (1).6 The linearity of the BE scaleis checked at a single point on the scale using a measurement of the position of either a specified core level of silver(monochromated Al source) or a specified Auger-
26、electron transition of copper (Mg source or unmonochromated Al source) (1, 2);additional checks can be made, if desired, with secondary standards. Procedures are given for determining the components of anuncertainty budget in BE measurements and for determining the uncertainties of BE measurements (
27、at the 95 % confidence level)at various times following a calibration. The analyst can thus establish tolerance limits, for example, at the same level ofconfidence, based on the instrument stability and the analystsanalysts needs so that BE measurements statistically are likely tobe made within thes
28、e limits during specified time intervals following a calibration. The instrument is then adjusted by followingthe procedures of the instrument manufacturer or subsequent BE measurements are corrected. corrected by following the procedureoutlined in this practice. For a routine check of the instrumen
29、tal calibration, either one or two measurements are made for eachof the same core levels of copper and gold. Fig. 1 is a flow chart that summarizes the steps of the calibration procedure; referencesare given to relevant sections of this standard.practice. An optional procedure is provided for determ
30、ining the average energy ofthe X-rays from a monochromated Al X-ray source, using a measured position of a copper Auger peak.5. Significance and Use5.1 X-ray photoelectron spectroscopy is used extensively for the surface analysis of materials. Elements (with the exception ofhydrogen and helium) are
31、identified from comparisons of the binding energies determined from photoelectron spectra withtabulated values. Information on chemical state can be derived from the chemical shifts of measured photoelectron andAuger-electron features with respect to those measured for elemental solids.5.2 Calibrati
32、ons of the BE scales of XPS instruments are required for four principal reasons. First, meaningful comparison ofBE measurements from two or more XPS instruments requires that the BE scales be calibrated, often with an uncertainty of about0.1 eV to 0.2 eV. Second, identification of chemical state is
33、based on measurement of chemical shifts of photoelectron andAuger-electron features, again with an uncertainty of typically about 0.1 eV to 0.2 eV; individual measurements, therefore, shouldbe made and literature sources need to be available with comparable or better accuracies. Third, the availabil
34、ity of databases (3)2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standardsstandards Document Summary page on the ASTM website.3 The last approved version of t
35、his historical standard is referenced on www.astm.org.4 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.5 https:/www.iso.org/obp/ui/#iso:std:iso:18115:-1:ed-2:v1:en.6 The boldface numbers in parentheses refer to the list
36、of references at the end of this standard.E2108 162of measured BEs for reliable identification of elements and determination of chemical states by computer software requires thatpublished data and local measurements be made with uncertainties of about 0.1 eV to 0.2 eV. Finally, the growing adoption
37、ofquality management systems, such as, ISO 9001:2000,9001:2015, in many analytical laboratories has led to requirements that themeasuring and test equipment be calibrated and that the relevant measurement uncertainties be known.TABLE 1 Definitions of Symbols and Abbreviationsa measured energy scalin
38、g errorBE binding energy, in eVb measured zero offset error, in eVci number of counts in the i-th channeleV electron voltsEcorr corrected result for the binding energy corresponding to a given Emeas, in eVEelem binding energy of a frequently measured element at which the indicated binding energy sca
39、le is set, aftercalibration, to read correctly, in eVEK kinetic energy of a peak, with reference to the Fermi level, in eVEmeas a measured binding energy, in eVEmeas n average of the measured binding energies for the peak, n, in Table 3, in eVEmeas ni one of a set of measurements of binding energy f
40、or the peak, n, in Table 3, in eVEref n reference values for the position of peak, n, in Table 3, on the binding energy scale, in eVEp peak binding energy, in eVE0 binding energy for first data channel at lower binding energy than the channel with the maximum number of counts,for a peak, in eVFWHM f
41、ull width at half maximum peak intensity above the background, in eVg channel energy separation, in eVhvAl effective X-ray energy from an unmonochromated Al X-ray source, in eVhv Almon effective X-ray energy from a monochromated Al X-ray source, in eVh Almon effective X-ray energy from a monochromat
42、ed Al X-ray source, in eVhvMg effective X-ray energy from an unmonochromated Mg X-ray source, in eVi index to represent channel number, where i = 0 represents the first channel at lower binding energy than the chan-nel with the maximum number of counts, for a peak, in eVj number of repeat measuremen
43、ts for a new peakk number of repeat measurements for the Au 4f7/2, Cu 2p3/2 and Ag 3d5/2 or Cu L3VV peaks in the repeatability stan-dard deviation and linearity determinationsm number of repeat measurements for the Au 4f7/2 and Cu 2p3/2 peaks in the regular calibrationsn designation of the peak iden
44、tifier in Table 3p parameter in Eq A1.1 and A1.1 defined in Eq A1.2 and A1.2p parameter in Eq A1.1, defined in Eq A1.2 and Section A1.2q parameter in Eq A1.1 and A1.1 defined in Eq A1.3 and A1.3q parameter in Eq A1.1, defined in Eq A1.3 and Section A1.2r parameter in Eq A1.1 and A1.1 defined in Eq A
45、1.4 and A1.4r parameter in Eq A1.1, defined in Eq A1.4 and Section A1.2tx Students t value for x degrees of freedom of a two-sided distribution for a confidence level of 95 %tx Students t value for x degrees of freedom of a two-sided distribution for a confidence level of 95 %U95 total uncertainty o
46、f the calibrated energy scale at a confidence level of 95 %, in eVU95c (E) uncertainty at a confidence level of 95 % arising from the calibration using the Au 4f7/2 and Cu 2p3/2 peaks at bind-ing energy E, assuming perfect scale linearity, in eVU951 uncertainty of 2 or 3 at a confidence level of 95
47、% from Eq 7 and 7, in eVU95l uncertainty of 2 or 3 at a confidence level of 95 % from Eq 7 and Section 8.9.3, in eVU95cl uncertainty of the calibration at a confidence level of 95 % in the absence of a linearity error, from Eq 12 and 12and Eq 13 and 13, in eVU95cl uncertainty of the calibration at a
48、 confidence level of 95 % in the absence of a linearity error, from Eq 12 or Eq 13and Section 8.10.4, in eVXPS X-ray photoelectron spectroscopy Auger parameter, in eV modified Auger parameter, in eVn offset energy, given by the average measured binding energy for a calibration peak minus the referen
49、ce energy, ineV, for n = 1, 2, 3, 4 in Table 3, for a given X-ray sourceEcorr correction to be added to Emeas, after calibration, to provide the corrected result for the binding energy, in eVEcorr n value of Ecorr for peaks 1 and 4 in Table 3, in eVEn drift of the binding-energy scale following a calibration for peaks 1 and 4 in Table 3, in eV the average of 1 and 4 from Eq 16 and 16, in eV the average of 1 and 4 from Eq 16 and Section 8.11.1.2, in eVhv difference between hvAlmon and hvAl, in eVhv difference between hAlmon and hv
