Basic XPS Information Section

The Basic XPS Information Section provides fundamental XPS spectra, BE values, FWHM values, overlays of key spectra, BE tables, histograms and a table of XPS parameters. The Advanced XPS Information Section is a collection of additional spectra, overlays of spectra, peak-fit advice, data collection guidance, material info, common contaminants, degradation during analysis, auto-oxidation, gas capture study, valence band spectra, Auger spectra, and more. Published literature references, and website links are summarized at the end of the advanced section. →  Periodic Table                      XPS Database of Polymers                    → Six (6) BE Tables

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Aluminum (Al)

 

Corundum – Al2O3	Aluminum Metal – Alo	Bauxite – Aluminum Oxide Ore

 

 

Page Index
Pure Element Spectra with Peak-fits IMFP and Cross-sections for Pure Element Native Oxide Spectra with Peak-fits Pure Oxide Spectra with Peak-fits	Valence Band Spectra Six (6) Tables of Chemical State BEs  Histograms of NIST BEs Advanced XPS Information Section	Peak-fits and Overlays of Au Chemical Compounds Flood Gun Effects on Native Oxide Spectra Study of UHV Gas Capture after Cleaning	Contamination XPS Facts, Guidance, Information Chemical State Spectra from Literature

• Expert Knowledge Explanations

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Aluminum (Al^o) Metal Peak-fits, BEs, FWHMs, and Peak Labels

Aluminum Metal (Alo) Al (2p) Spectrum – raw Ion etched clean	Aluminum Metal (Alo) Peak-fit of Al (2p) Spectrum – no asymm
Aluminum (Alo) Metal Al (2p) & (2s) Spectrum Aluminum (Alo) Metal Peak-fit of Al (2p) Spectrum (w asymm)   Aluminum (Alo) Metal Al (2s) Spectrum – raw Aluminum (Alo) Metal Peak-fit of Al (2s) Spectrum (w asymm)     Survey Spectrum of Aluminum (Alo) Metal with Peaks Integrated, Assigned and Labelled
→  Periodic Table
XPS Signals for Aluminum, (Alo) Metal Spin-Orbit Term,  BE (eV) Value, and Scofield σ for Aluminum Kα X-rays (1486 eV, 8.33 Ang) Overlaps Spin-Orbit Term BE (eV) Value Scofield σ from 1486 eV X-rays IMFP (TPP-2M) in Å Cu (3s) overlaps Al (2s) 117.8 0.753 30.3 Pt (4f), Cu (3p), Cs (4d) overlap Al (2p) 73.9 0.537 32.1   Al (2p3/2) 72.71 0.537 32.1 σ:  abbreviation for the term Scofield Photoionization Cross-Section which is used with IMFP and TF to generate RSFs and atom % quantitation Bulk Plasmon Peaks for Alo metal ~16 ev Energy Loss Peaks for Al2O3 ~24 eV Expected Bandgap for Al2O3: 7 – 7.6 eV *Scofield Cross-Section (σ) for C (1s) = 1.0     Valence Band Spectrum from Alo Metal  Fresh exposed bulk produced by extensive Ar+ ion etching →  Periodic Table    Plasmon Peaks from AloMetal Fresh exposed bulk produced by extensive Ar+ ion etching Al (2p) – Extended Range Spectrum Al (2p) – Extended Range Spectrum  – Vertically Expanded   Comparison of Alo Metal Plasmon Peaks to Al2O3 Energy Loss Peaks Al (2p & 2s) – Plasmon Peaks from Al Metal Al (2p & 2s) – Energy Loss Peaks from Al2O3     Plasmon Peaks from Alo Metal – vertically expanded Energy Loss Peaks from Al2O3 – vertically expanded →  Periodic Table  Comparison of Al (2p) and Al (2s) Plasmon Peaks from Aluminum Alo metal and Energy Loss Peaks from Aluminum Oxide, Al2O3     Artefacts Caused by Argon Ion Etching C (1s) from Aluminum Carbide(s)         Argon Trapped in ALo na na   Side-by-Side Comparison of Aluminum (Al) Native Oxide & Aluminum Oxide, Al2O3  Peak-fits, BEs, FWHMs, and Peak Labels
Al (2p) from Al Native Oxide on Aluminum metalAs-Measured – Not Ion Etched	Al (2p) from Al2O3 fresh exposed bulk Charge Referenced to 285.0 eV
C (1s) from Al Native Oxide on Aluminum metal As-Measured	C (1s) from Al2O3 fresh exposed bulk Charge Referenced to 285.0 eV
O (1s) from Al Native Oxide on Aluminum metal As-Measured	O (1s) from Al2O3  fresh exposed bulk Charge Referenced to 285.0 eV
Al (2s) from Al Native Oxide on Aluminum metal As-Measured	Al (2s) from Al2O3 (no asymm, GLS fit) fresh exposed bulk Charge Referenced to 285.0 eV

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Survey Spectrum of Aluminum (Al) Native Oxide with Peaks Integrated, Assigned and Labelled

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Survey Spectrum of Aluminum Oxide (Al₂O₃) with Peaks Integrated, Assigned and Labelled

  →  Periodic Table 

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Overlays of Al (2p) Spectra for Al^o metal, Al Native Oxide and Al₂O₃ Caution: BEs from Grounded Native Oxides can be Misleading when FG is ON

Pure Alo Metal and Al Native Oxide – Al (2p) Thickness Oxide can shift BEs for a Grounded Sample (floating native oxides gives more reliable results)	Pure Alo Metal and Al2O3 – Al (2p) C (1s) = 285.0 eV
Pure Alo Metal, Al Native Oxide & Al2O3 – Al (2p) C (1s) = 285.0 eV	Pure Alo Metal, Al Native Oxide & Al2O3 – Al (2p) C (1s) = 286.8 eV (as measured)
	Copyright ©:  The XPS Library

Features Observed

• xx
• xx
• xx

→  Periodic Table 

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Valence Band Spectra Al^o, Al₂O₃ 

Alo metal	Al2O3

 

Overlay of Valence Band Spectra for Al^o metal and Al₂O₃  

Copyright ©:  The XPS Library

→  Periodic Table 

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Side-by-Side Comparison of Al₂O₃ (amorphous alumina)  &  AlO(OH) (single crystal) Peak-fits, BEs, FWHMs, and Peak Labels

Al (2p) of Al2O3 – exposed bulk	Al (2p) of AlO(OH) – exposed bulk
Overlay of Al (2p) from Al2O3 and AlO(OH)
→  Periodic Table  O (1s) Spectra from Al2O3 and AlO(OH)
O (1s) of Al2O3 – exposed bulk	O (1s) of AlO(OH) – exposed bulk
Overlay of O (1s) from Al2O3 and AlO(OH)
Valence Band of Al2O3 – exposed bulk	Valence Band of AlO(OH) – exposed bulk
Overlay of Valence Band Spectra  from Al2O3 and AlO(OH)
→  Periodic Table
Overlay of O (KLL) Auger Spectra from Al2O3 and AlO(OH)

 

Survey Spectrum of Aluminum Oxide (Al₂O₃) with Peaks Integrated, Assigned and Labelled

 

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Survey Spectrum of Aluminum Oxyhydroxide AlO(OH) (Diaspore) with Peaks Integrated, Assigned and Labelled

 

 

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Aluminum Minerals, Gemstones, and Chemical Compounds
Diaspore – AlOOH	Spinel – MgAl2O4	Morganite – Be3Al2SiO6	AlF3

→  Periodic Table 

 

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Six (6) Chemical State Tables of Al (2p) BEs

 

• The XPS Library Spectra-Base
• PHI Handbook
• Thermo-Scientific Website
• XPSfitting Website
• Techdb Website
• NIST Website

→  Periodic Table   

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  Notes of Caution when using Published BEs and BE Tables from Insulators and Conductors:

• Accuracy of Published BEs
  • The accuracy depends on the calibration BEs used to calibrate the energy scale of the instrument.  Cu (2p_3/2) BE can vary from 932.2 to 932.8 eV for old publications
  • Different authors use different BEs for the C (1s) BE of the hydrocarbons found in adventitious carbon that appears on all materials and samples.  From 284.2 to 285.3 eV
  • The accuracy depends on when the authors last checked or adjusted their energy scale to produce the expected calibration BEs
• There are uncertainties and error ranges in nearly all BEs 
  • Flood guns
• Worldwide Differences in Energy Scale Calibrations
  • For various reasons authors still use older energy scale calibrations
  • Some authors still adjust their energy scale so Cu (2p_3/2) appears at 932.2 eV or 932.8 eV because this is what the maker taught them
  • This range causes BEs in the higher BE end to be larger than expected
  • This variation increases significantly above 600 eV BE
• Charge Compensation
  • Samples that behave as true insulators normally require the use of a charge neutralizer (electron flood gun with or without Ar+ ions) so that the measured chemical state spectra can be produced without peak-shape distortions or sloping tails on the low BE side of the peak envelop.
  • Floating all samples (conductive, semi-conductive, and non-conductive) and always using the electron flood gun is considered to produce more reliable BEs and is recommended.
• Charge Referencing Methods for Insulators
  • Charge referencing is a common method, but it can produce results that are less reliable.
  • When an electron flood gun is used, the BE scale will usually shift to lower BE values by 0.01 to 5.0 eV depending on your voltage setting. Normally, to correct for this flood gun induced shift, the BE of the hydrocarbon C (1s) peak maximum from adventitious carbon is used to correct for the charge induced shift.
  • The hydrocarbon peak is normally the largest peak at the lowest BE.
  • Depending on your preference or training, the C (1s) BE assigned to this hydrocarbon peak varies from 284.8 to 285.0 eV.  Other BEs can be as low as 284.2 eV or as high as 285.3 eV
  • Native oxides that still show the pure metal can suffer differential charging that causes the C (1s) and the O (1s) and the Metal Oxide BE to be larger
  • When using the electron flood gun, the instrument operator should adjust the voltage and the XY position of the electron flood gun to produce peaks from a strong XPS signal (eg O (1s) or C (1s) having the most narrow FWHM and the lowest experimentally measured BE.

→  Periodic Table    Table #1

Al (2p) Chemical State BEs from:  “The XPS Library Spectra-Base”

C (1s) BE = 285.0 eV for TXL BEs and C (1s) BE = 284.8 eV for NIST BEs

Element	Atomic #	Compound	As-Measured by TXL or NIST Average BE	Largest BE	Hydrocarbon C (1s) BE	Source
Al	13	Al – element	72.9 eV		285.0	The XPS Library
Al	13	AlGaAs	74.1 eV		285.0	The XPS Library
Al	13	Al2O3 (N*3)	74.3 eV	74.7 eV	284.8	Avg BE – NIST
Al	13	Al-N	74.3 eV		285.0	The XPS Library
Al	13	Pyrope	74.4 eV		285.0	The XPS Library
Al	13	Mica	74.5 eV		285.0	The XPS Library
Al	13	Al2SiO5	74.7 eV		285.0	The XPS Library
Al	13	Al2(SO4)3 (N*1)	74.9 eV		284.8	Avg BE – NIST
Al	13	LiAlSi2O6	75.3 eV		285.0	The XPS Library
Al	13	Al2O3/Al	75.4 eV	75.9 eV	285.0	The XPS Library
Al	13	Al2O3-TiC	75.4 eV		285.0	The XPS Library
Al	13	Al2O3/Al (N*16)	75.6 eV	75.8 eV	284.8	Avg BE – NIST
Al	13	Al-OOH	75.7 eV		285.0	The XPS Library
Al	13	Al(OH)3	76.2 eV		285.0	The XPS Library
Al	13	Al-F3	77.0 eV		285.0	The XPS Library
Al	13	Al-Br3			285.0	The XPS Library
Al	13	Al-CO3			285.0	The XPS Library
Al	13	Al-SO4			285.0	The XPS Library

Charge Referencing

• (N*number) identifies the number of NIST BEs that were averaged to produce the BE in the middle column.
• Binding Energy Scale Calibration expects Cu (2p_3/2) BE = 932.62 eV and Au (4f_7/2) BE = 83.98 eV.  BE (eV) Uncertainty Range:  +/- 0.2 eV
• Charge Referencing of insulators is defined such that the Adventitious Hydrocarbon C (SO) BE (eV) = 285.0 eV.  NIST uses C (1s) BE = 284.8 eV 
• Note:   Ion etching removes adventitious carbon, implants Ar (+), changes conductivity of surface, and degrades chemistry of various chemical states.
• Note:  Ion Etching changes BE of C (1s) hydrocarbon peak.
• TXL – abbreviation for: “The XPS Library” (https://xpslibrary.com).  NIST:  National Institute for Science and Technology (in USA)

 →  Periodic Table 

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Table #2

Al (2p) Chemical State BEs from:  “PHI Handbook”

C (1s) BE = 284.8 eV

Copyright ©:  Ulvac-PHI

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Table #3

Al (2p) Chemical State BEs from:  “Thermo-Scientific” Website

C (1s) BE = 284.8 eV

Chemical State	Binding Energy – Al (2p)
Al metal	72.6 eV
Aluminosilicate	74.4 eV
Al oxide	74.6 eV
Al oxide on Al foil	75.6 eV

Copyright ©:  Thermo Scientific website

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Table #4

Al (2p) Chemical State BEs from:  “XPSfitting” Website

Chemical State BE Table derived by Averaging BEs in the NIST XPS database of BEs C (1s) BE = 284.8 eV

Copyright ©:  Mark Beisinger

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Table #5

Al (2p) Chemical State BEs from:  “Techdb.podzone.net” Website

XPS Spectra – Chemical Shift | Binding Energy C (1s) BE = 284.6 eV

Element	Level	Compound	B.E. (eV)		min		max
Al	2p	Al	72.8	±0.3	72.5	～	73.0
Al	2p	AlAs	73.6	±0.3	73.3	～	73.9
Al	2p	AlGaAs	73.7	±0.4	73.3	～	74.0
Al	2p	Al2O3, alpha	73.9	±0.3	73.6	～	74.2
Al	2p	Al2O3, gamma	74.0	±0.3	73.7	～	74.3
Al	2p	Al2O3, sapphire	74.2	±0.3	73.9	～	74.5
Al	2p	AlOOH, boehmite	74.3	±0.3	74.0	～	74.6
Al	2p	Oxides	74.5	±0.3	74.2	～	74.8
Al	2p	Halides	75.4	±0.9	74.5	～	76.3
Al	2p	LiAlH4	75.6	±0.4	75.2	～	76.0
Al	2p	AlF3	76.4	±0.4	76.0	～	76.7

 

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Advanced XPS Information Section

Spectra, BEs, Features, Guidance and Cautions for XPS Research Studies on Aluminum Materials

 

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Statistical Analysis of Binding Energies in NIST XPS Database of BEs

 

 

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XPS Spectra

from Common Aluminum Compounds

                           

Pure Aluminum, Alo:  Al (2p) (repeatedly ion etched and measured very quickly)	Aluminum Oxide, Al2O3:  Al (2p) C (1s) BE = 285.0	Aluminum Fluoride, AlF3:  Al (2p) C (1s) BE = 285.0

Features Observed

• xx
• xx
• xx

→  Periodic Table 

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Overlay of Al (2p) Spectra shown Above

C (1s) BE = 285.0 eV

 

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Native Oxide on Aluminum Al^o Metal Naturally Formed at 25 C^o 1 atm

Survey Spectrum from Native Oxide on Alo metal	Al (2p) Chemical State Spectrum from Native Oxide on Alo
Valence Band Spectrum from Native Oxide on Alo	Valence Band Spectrum from Exposed Bulk of Al2O3 C (1s)=285.0 eV
C (1s) Spectrum from Native Oxide of Alo	O (1s) Spectrum from Native Oxide of Alo

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Flood Gun Effects on Native Oxide of Aluminum

 

Native Oxide of Aluminum Foil – Sample GROUNDED Differential Shifting is Present versus Native Oxide of Aluminum Foil – Sample FLOATING (All Peaks Shift Linearly)

 

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  Features Observed

• xx
• xx
• xx

→  Periodic Table 

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Aluminum Oxide (Al₂O₃) fused – amorphous – Alumina

Survey Spectrum from Al2O3	Al (2p) Chemical State Spectrum from Al2O3
.
O (1s) Chemical State Spectrum from Al2O3	C (1s) Chemical State Spectrum from Al2O3

 

Overlay of Al (2p) and Al (2s) Peaks showing the Difference between “p” and “s” peak-shapes.

Features Observed

• xx
• xx
• xx

→  Periodic Table 

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Valence Band Spectra Comparison Al^o,  Al₂O₃

Alo metal Ion Etched Repeatedly to keep Clean	Al2O3 – exposed bulk Charge Referenced so C (1s) =285.0 eV

Features Observed

• xx
• xx
• xx

→  Periodic Table 

 

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Chemical State Auger Spectra using HSA (CHA)

Aluminum metal by Auger with Hemi-sphere (HSA) – 25 kV	Al2O3 – fused – 25 kV, T=55

Features Observed

• xx
• xx
• xx

→  Periodic Table 

Copyright ©:  The XPS Library  

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XPS Facts, Guidance & Information

→  Periodic Table 

		Element		Aluminum (Al)
		Primary XPS peak used for Peak-fitting :		Al (2p)
		Spin-Orbit (S-O) splitting for Primary Peak:		Spin-Orbit splitting for “p” orbital = ~0.4 eV
		Binding Energy (BE) of Primary XPS  Signal:		72.9 eV
		Scofield Cross-Section (σ) Value:		Al (2p) = 0.537
		Conductivity:		Metal form is very conductive Aluminum Resistivity = 26.5 nΩ⋅m (at 20 °C) Al2O3 Resistivity = 1×1014 Ω ·cm Flood gun on Native oxide causes differential charging
		Range of Al (2p) Chemical State BEs:		73-77 eV range   (Alo to AlF3)
		Signals from other elements that overlap Al (2p) Primary Peak:		Pt (4f), Cu (3p), Cs (4d)
		Bulk Plasmons:		~16 eV above peak BE max
		Shake-up Peaks:		xx
		Multiplet Splitting Peaks:		not possible
		General Information about XXX Compounds:		xx
		Cautions – Chemical Poison Warning		xx

Copyright ©:  The XPS Library 

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Information Useful for Peak-fitting Al (2p)

• FWHM (eV) of Al (2p_3/2) from Pure Aluminum metal:  ~0.35 eV using 25 eV Pass Energy after ion etching and very fast data collection cycles
• FWHM (eV) of Al (2p_3/2) from Al₂O₃:  ~1.39-1.60 eV using 50 eV Pass Energy  (before ion etching)
• Binding Energy (BE) of Primary Signal used for Measuring Chemical State Spectra:  73 eV for Al (2p) with +/- 0.2 uncertainty
• List of XPS Peaks that can Overlap Peak-fit results for Al (2p):  Pt, Ni, Cu, Pr

→  Periodic Table 

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General Guidelines for Peak-fitting XPS Signals

• Typical Energy Resolution for Pass Energy (PE) setting used to measure Chemical State Spectra on Various XPS Instruments
  • Ag (3d_5/2) FWHM (eV) = ~0.95 eV for PE 50 on Thermo K-Alpha
  • Ag (3d_5/2) FWHM (eV) = ~1.00 eV for PE 80 on Kratos Nova
  • Ag (3d_5/2) FWHM (eV) = ~0.95 eV for PE 45 on PHI VersaProbe
• FWHM (eV) of Pure Elements: Ranges from 0.4 to 1.0 eV across the periodic table
• FWHM of Chemical State Peaks in any Chemical Compound:  Ranges from 1.1 to 1.6 eV  (in rare cases FWHM can be 1.8 to 2.0 eV)
• FWHM of Pure Element versus FWHM of Metal Oxide:  Pure element FWHM << Metal Oxide FWHM  (e.g. 0.8 vs 1.5 eV, roughly 2x)
• If FWHM Greater than 1.6 eV:  When a peak FWHM is larger than 1.6 eV, it is best to add another peak to the peak-fit envelop.
• BE (eV) Difference in Chemical States: The difference in chemical state BEs is typically 1.0-1.3 eV apart.  In rare cases, <0.8 eV.
• Number of Peaks to Use:  Use minimum. Do not use peaks with FWHM < 1.0 eV unless it is a metal or a conductive compound.
• Typical Peak-Shape:  80% G: 20% L,   1.4 eV Gaussian and 0.5 eV Lorentzian
• Spin-Orbit Splitting of Two Peaks (due to Coupling):  The ratio of the two (2) peak areas can be constrained but it is difficult due to the 0.4 eV separation.
• Constraints on Peak-fitting: It is difficult to use the 2p3/2 : 2p1/2 area ratio to constrain peaks in chemical state spectra because the peaks are only 0.4 eV apart

Notes:

• Other Oxidation States such as Al₂O or AlOOH can appear as small peaks when peak-fitting
• Pure element signals normally have asymmetric tails that should be included in the peak-fit.
• Peak-fits of C (SO) in polymers include an asymmetric tail when the energy resolution is very high.
• Binding energy shifts of some compounds are negative due to unusual electron polarization.

→  Periodic Table 

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Quantitation Details and Information

Quantitation by XPS is often incorrectly done, in many laboratories, by integrating only the main peak, ignoring the Electron Loss peak, and the satellites that appear as much as 30 eV above the main peak.  By ignoring the electron loss peak and the satellites, the accuracy of the atom% quantitation is in error. When using theoretically calculated Scofield cross-section values, the data must be corrected for the transmission function effect, use the calculated TPP-2M IMFP values, the pass energy effect on the transmission function, and the peak area used for calculation must include the electron loss peak area, shake-up peak area, multiplet-splitting peak area, and satellites that occur within 30 eV of the main peak.

→  Periodic Table 

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Contaminants Specific to Aluminum

• Aluminum metal develops a native oxide that is usually 6-7 nm thick.  .
• With heat the native oxide becomes thicker and the BE of the oxide shifts to higher BE
• Aluminum does not readily form a carbide when the surface is ion etched inside the analysis chamber

 

Commonplace Contaminants

• Carbon and Oxygen are common contaminants that appear on nearly all surfaces. The amount of Carbon usually depends on handling.
• Carbon is usually the major contaminant.  The amount of carbon ranges from 5-50 atom%.
• Carbon contamination is attributed to air-borne organic gases that become trapped by the surface, oils transferred to the surface from packaging containers, static electricity, or handling of the product in the production environment.
• Carbon contamination is normally a mixture of different chemical states of carbon (hydrocarbon, alcohol or ether, and ester or acid).
• Hydrocarbon is the dominant form of carbon contamination. It is normally 2-4x larger than the other chemical states of carbon.
• Carbonate peaks, if they appear, normally appear ~4.5 eV above the hydrocarbon C (SO) peak max BE.
• Low levels of carbonate is common on many metals that readily oxidize in the air.
• High levels of carbonate appear on reactive metal oxides and various hydroxides.  This is due to reaction between the oxide and CO₂ in the air.
• Hydroxide contamination peak is due to the reaction with residual water in the lab air or the vacuum.
• The O (SO) BE of the hydroxide (water) contamination normally appears 0.5 to 1.0 eV above the oxide peak
• Sodium (Na), Potassium (K), Sulfur (S) and Chlorine (Cl) are common trace to low level contaminants
• To find low level contaminants it is very useful to vertically expand the 0-600 eV region of the survey spectrum by 5-10X
• A tiny peak that has 3 or more adjacent data-points above the average noise of the background is considerate to be a real peak
• Carbides can appear after ion etching various reactive metals.  Carbides form due to the residual CO and CH₄ in the vacuum.
• Ion etching can produce low oxidation states of the material being analyzed.  These are newly formed contaminants.
• Ion etching polymers by using standard Ar+ ion guns will destroy the polymer, converting it into a graphitic type of carbon

→  Periodic Table 

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Data Collection Guidance

• Chemical state differentiation can be difficult
• To record the 0.4 eV splitting between Al (2p_3/2) and Al (2p_1/2), you can collect spectra very, very quickly using a very short analysis time (10-20 seconds for a 15 eV window) that is stored as one spectrum.  Then repeat fresh ion etch and repeat short analysis time for ~20 different measurements, then add all spectra together.
• Long time exposures (high dose) to X-rays can degrade various polymers, catalysts, high oxidation state compounds
• During XPS analysis, water or solvents can be lost due to high vacuum or irradiation with X-rays or Electron flood gun
• Auger signals can sometimes be used to discern chemical state shifts when XPS shifts are very small

→  Periodic Table 

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Data Collection Settings for Al (2p)

• Conductivity:  Aluminum readily develops a native oxide that is sensitive to Flood Gun – Differential Charging Possible – float sample recommended
• Primary Peak (XPS Signal) used to measure Chemical State Spectra:  Al (2p) at 73 eV
• Recommended Pass Energy for Measuring Chemical State Spectrum:  40-50 eV    (Produces Ag (3d_5/2) FWHM ~0.8 eV)
• Recommended # of Scans for Measuring Chemical State Spectrum:  4-5 scans normally   (Use 10-25 scans to improve S/N)
• Dwell Time:  50 msec/point
• Step Size:  0.1 eV/point   (0.1 eV/step or 0.1 eV/channel)
• Standard BE Range for Measuring Chemical State Spectrum:  65-85 eV
• Recommended Extended BE Range for Measuring Chemical State Spectrum:  60-110 eV
• Recommended BE Range for Survey Spectrum:  -10 to 1,100 eV   (above 1,100 eV there are no useful XPS signals, except for Ge and Ga)
• Typical Time for Survey Spectrum:  3-5 minutes for newer instruments, 5-10 minutes for older instruments
• Typical Time for a single Chemical State Spectrum with high S/N:  5-10 minutes for newer instruments, 10-15 minutes for older instruments 

→  Periodic Table 

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Effects of Argon Ion Etching

• Al₂O₃ is one of the very few metal oxides that are not readily degraded or reduced by mono-atomic Ar+ ion etching (0.2 to 5.0 keV)
• Carbides can appear after ion etching various reactive metals.  Carbides form due to the residual CO and CH₄ in the vacuum.
• Ion etching can produce low oxidation states of the material being analyzed.  These are newly formed contaminants.
• Ion etching polymers by using standard Ar+ ion guns will destroy the polymer, converting it into a graphitic type of carbon

→  Periodic Table 

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