1、Designation: E 984 06Standard Guide forIdentifying Chemical Effects and Matrix Effects in AugerElectron Spectroscopy1This standard is issued under the fixed designation E 984; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide outlines the types of chemical effects andmatrix effects which are observed in Auger electron spectro
3、s-copy.1.2 Guidelines are given for the reporting of chemical andmatrix effects in Auger spectra.1.3 Guidelines are given for utilizingAuger chemical effectsfor identification or characterization.1.4 This guide is applicable to both electron excited andX-ray excited Auger electron spectroscopy.1.5 T
4、his standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Docume
5、nts2.1 ASTM Standards:2E 673 Terminology Relating to Surface AnalysisE 827 Practice for Indentifying Elements by the Peaks inAuger Electron SpectroscopyE 983 Guide for Minimizing Unwanted Electron BeamEffects in Auger Electron SpectroscopyE 996 Practice for Reporting Data in Auger Electron Spec-tros
6、copy and X-ray Photoelectron Spectroscopy2.2 Other Documents:ISO 18118:2004 Surface Chemical AnalysisAuger Elec-tron Spectroscopy and X-ray PhotoelectronSpectroscopyGuide to the Use of Experimentally De-termined Relative Sensitivity Factors for the QuantitativeAnalysis of Homogenous Materials3. Term
7、inology3.1 Terms used in Auger electron spectroscopy are definedin Terminology E 673.4. Significance and Use4.1 Auger electron spectroscopy is often capable of yieldinginformation concerning the chemical and physical environmentof atoms in the near-surface region of a solid as well as givingelementa
8、l and quantitative information. This information ismanifested as changes in the observedAuger electron spectrumfor a particular element in the specimen under study comparedto the Auger spectrum produced by the same element when itis in some reference form. The differences in the two spectraare said
9、to be due to a chemical effect or a matrix effect.Despite sometimes making elemental identification and quan-titative measurements more difficult, these effects in the Augerspectrum are considered valuable tools for characterizing theenvironment of the near-surface atoms in a solid.5. Defining Auger
10、 Chemical Effects and Matrix Effects5.1 In general,Auger chemical and matrix effects may resultin (a) a shift in the energy of anAuger peak, (b) a change in theshape of an Auger electron energy distribution, (c) a change inthe shape of the electron energy loss distribution associatedwith an Auger pe
11、ak, or (d) a change in the Auger signalstrengths of an Auger transition. The above changes may bedue to the bonding or chemical environment of the element(chemical effect) or to the distribution of the element orcompound within the specimen (matrix effect).5.2 The Auger chemical shift is one of the
12、most commonlyobserved chemical effects. A comparison can be made to themore familiar chemical shifts in XPS (X-ray photoelectronspectroscopy) photoelectron lines, where energy shifts arecaused by changes in the ionic charge on an atom, the latticepotential at that atomic site, and the final-state re
13、laxationenergy contributed by adjacent atoms (1 and 2).3Coverage bygas adsorbates on metal surfaces may also cause shifts in the1This guide is under the jurisdiction of ASTM Committee E42 on SurfaceAnalysis and is the direct responsibility of Subcommittee E42.03 on Auger ElectronSpectroscopy and X-R
14、ay Photoelectron Spectroscopy.Current edition approved Nov. 1, 2006. Published November 2006. Originallyapproved in 1984. Last previous edition approved in 2001 as E 984 95 (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org
15、. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The boldface numbers in parentheses refer to the references at the end of thisstandard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1942
16、8-2959, United States.metal Auger peak energies (3). The magnitude of the Augerchemical shift will usually be different from the XPS photo-electron shift because the Auger process involves a two-holefinal state for the atom which is more strongly influenced byextra-atomic relaxation. Frequently an A
17、uger chemical shift islarger than an XPS chemical shift (see Fig. 1).5.2.1 Related to chemical shifts is the (modified) Augerparameter, defined as the sum of the photoelectron bindingenergy and the Auger electron kinetic energy (4). Because theAuger parameter is the difference between two line energ
18、ies ofthe same element of the same specimen, it is independent ofany electrical charging of the specimen and spectrometerenergy reference level, making it easier to identify chemicalstates of elements in insulating specimens. Naturally, sinceboth photoelectron lines andAuger lines must be measured,
19、theAuger parameter can only be used with X-ray excited spectra.5.3 The second category of chemical information fromAuger spectroscopy is the Auger lineshapes observed fortransitions involving valence electron orbitals. Shown in Fig. 2and Fig. 3 are selected lineshapes for electron-excited carbonKLL
20、and aluminum LVVAuger transitions for different chemi-cal states of those elements. While it is possible to relate theprominent peaks in the Auger spectrum to transitions fromparticular bands in the density of states (for solids) or toparticular molecular orbitals (for molecules) (5), this is not an
21、easy task. The large number of possible two-hole final states,taken together with shake-up and shake-off transitions anduncertainty on all their final energies and intensities make thejob of constructing a valence orbital density map from theAuger spectrum next to impossible for all but the simplest
22、systems. Further, some spectra exhibit a quasiatomic character(6). Accordingly, most studies use the “fingerprint” approachwhen attempting to identify unknown species based on theirAuger lineshape. Of course reference spectra are necessary inthis approach for a positive identification. “Surface Scie
23、nceSpectra” is an international journal devoted to archivingsurface science spectra of technological and scientific interest(17)5.4 Other effects besides energy shifts and valence line-shapes may be classified as chemical effects in Auger spectros-copy. For instance, many body effects in metals, suc
24、h asplasmons, may make the lineshapes of Auger transitions ofFIG. 1 Comparison of X-ray Excited Cd MNN Auger and 3dPhotoelectron Energy Shifts for Cd Metal, CdO, and CdF2(Ref 13)FIG. 2 Carbon KLL Auger Spectra for Mo2C, SiC, Graphite, andDiamond (Ref 14)(a) Almost no Oxidation (b) Partial Oxidation
25、(c) After Oxidation hasReached a Satura-tion StageFIG. 3 Changes in the Aluminum LVV Auger spectrum asOxygen is Absorbed on the Surface (Ref 15)E984062atoms in the metallic state very different from the Augerlineshapes for other chemical states, even for transitionsinvolving only core-type electrons
26、, Al and Mg (7). In singlecrystals, diffraction effects will produce different lineshapes(8). Relative intensities of several Auger transitions maychange, either from attenuation of overlayers (9), or fromdifferent chemical states resulting in different Auger transitionprobabilities (10 and 11). Pho
27、non broadening and inelasticelectron energy loss effects will result in different linewidthsand backgrounds for gases, adsorbates, and condensed phases(12).5.5 For both X-ray and electron excited Auger spectra,quantitative corrections for matrix effects are discussed indetail in ISO 18118: 2004.6. G
28、uidelines for Reporting Auger Chemical and MatrixEffects6.1 In general, the guidelines outlined in Practice E 996should be used. This practice covers reporting of the spectrom-eter, specimen preparation, excitation source, analyzer anddetector modes, and data processing. Also, if measures weretaken
29、to control damage or charging of the specimen, reportthose conditions in a manner consistent with Guide E 983.6.1.1 Practice E 827 should be used to confirm the elemen-tal identification. The elemental information should be consis-tent with the presumed chemical state identification.6.1.2 When repor
30、ting chemical and matrix effects in anAuger spectrum, the main feature of interest is the Auger peakenergy (reported in eV). This is the energy of the largestnegative excursion in the dN/dE spectrum or the most intensepeak in the N(E) spectrum. (Of course, these two peakpositions measurements will h
31、ave different energy values.)The energy location of the major Auger peak should be inagreement with the reference value, consistent with the experi-mental parameters and calibrations as discussed in PracticeE 996.6.1.3 The reference level for the energy scale of the electronenergy analyzer and the m
32、ethod for calibrating the energy scaleshould be specified. The relative peak energy shifts betweenthe chemical states of interest and that element in its elementalstate (or some other standard state) should also be reported.6.1.4 Other spectral features which may be useful includethe number, relativ
33、e energy positions, and relative signalstrengths of the secondary peaks. The reporting of these valuesshould also be in agreement with the reference value andconsistent with the experimental parameters and calibrationsdiscussed in Practice E 996.6.2 When spectra are presented for publication, the en
34、ergyrange should be wide enough that the shape of the backgroundon either side of theAuger line is apparent. Shown in Fig. 4 areAuger spectra for several sulfur-containg compounds, and inTable 1 information from these spectra.7. Keywords7.1 Auger electron spectroscopy; chemical effect; matrixeffect;
35、 spectroscopyTABLE 1 Sulfur in Sulfur CompoundsNOTE 1Data Compiled From Auger Spectra (Ref 16).Compound Electron Excited LVVA,BNew PeakADEA,CX-ray Excited LVVA,DAuger Parameter PlusPhoton EnergyA,DK2SO4138.7 123.9 11.7 . .Ag2SO4141.7 127.4 8.7 . .Na2SO4138.3 123.0 12.1 . .Na2SO3139.1 124.8 11.3 . .K
36、2SO3139.4 124.5 11.0 . .Ag2S 150.4 . . 149.3 516.9AEnergy in eV.BZero point of derivative spectra.CAg2S used for reference.DAl Ka X rays.FIG. 4 Sulfur LVV Auger Spectra for Ag2SO4,Na2SO4,K2SO4,Na2SO3,K2SO3,Ag2S, CdS (Ref 16)E984063REFERENCES(1) Wagner, C. D., and Biloen, P. “X-ray Excited Auger and
37、PhotoelectronSpectra of Partially Oxidized Magnesium Surfaces: The Observationof Abnormal Chemical Shifts,” Surface Science, Vol 35, 1973, pp.8295.(2) Wagner, C. D., “Chemical Shifts of Auger Lines, and the AugerParameter,” Discussions of the Faraday Society, Vol 60, 1975, pp.291300.(3) Haas, T. W.,
38、 and Grant, J. T., “Chemical Shifts in Auger ElectronSpectroscopy from the Initial Oxidation of Ta(110),” Physics Letters,Vol 30A, 1969, p. 272.(4) Wagner, C. A., Gale, L. H., and Raymond, R. H., “Two-DimensionalChemical State Plots: A Standardized Data Set for Use in IdentifyingChemical States by X
39、-ray Photoelectron Spectroscopy,” AnalyticalChemistry, Vol 51, 1979, pp. 466482.(5) Jennison, D. R., “Understanding Core-Valence-Valence Auger Line-shapes,” Journal of Vacuum Science and Technology, Vol 20, 1982, pp.548554.(6) Sawatsky, G. A., “Quasiatomic Auger Spectra in Narrow-BandMetals,” Physic
40、al Review Letters, Vol 39, 1977, pp. 504-507.(7) Palmberg, P. W., “Quantitative Analysis of Solid Surfaces by AugerElectron Spectroscopy,” Analytical Chemistry, Vol 45, 1973, pp.549A556A.(8) Chang, C. C., “Intensity Variations in Auger Spectra Caused byDiffraction,” Applied Physics Letters, Vol 31,
41、1977, pp. 304306.(9) Holloway, P. H., “Thickness Determination of Ultrathin Films byAuger Electron Spectroscopy,” Journal of Vacuum Science and Tech-nology, Vol 12, 1975, pp. 14181422.(10) Weissmann, R., “Intensity Ratios of the KL1L1,KL23L23OxygenAuger Lines in Different Compounds,” Solid State Com
42、munications,Vol 31, 1979, pp. 347349.(11) Sarma, D. D., Hegde, M. S., and Rao, C. N. R., “An AugerSpectroscopic Study of the Surface Oxidation of Zinc,” ChemicalPhysics Letters, Vol 73, 1980, pp. 443446.(12) Houston, J. E. and Rye, R.R., “ChemicalAnalysis of Solid Surfaces,”Encyclopedia of Materials
43、 Science and Engineering, PergamonPress, Oxford, UK, Vol 1, 1986, pp 617622.(13) Gaarenstroom, S. W., and Winograd, N., “Initial and Final StateEffects in the ESCASpectra of Cadmium and Silver Oxides,” Journalof Chemical Physics, Vol 67, 1977, pp. 35003506.(14) Haas, T. W., Grant, J. T., and Dooley,
44、 III, G. J., “Chemical Effects inAuger Electron Spectroscopy,” Journal of Applied Physics, Vol 43,1972, pp. 18531860.(15) Suleman, M., and Pattinson, E. B., “Observation of a Plasmon-Gainin the Fine Structure of the Aluminum Auger Spectrum,” Journal ofPhysics, F: Metal Physics, Vol 1, 1971, pp. L21L
45、24.(16) Turner, N. H., Murday, J. S., and Ramaker, D. E., “QuantitativeDetermination of Surface Composition of Sulfur Bearing AnionMixtures by Auger Electron Spectroscopy,” Analytical Chemistry,Vol 52, 1980, pp. 8492.(17) Surface Science Spectra, published by American Vacuum Society.ASTM Internation
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49、 at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E984064
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