Alo Al2O3 Al(OH)3 AlO(OH) Al2(SO4)3  Al4C3 LiAlO2 AlF3 Al6Si2O13  BeAl2O4 AlN YAlO3    

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


 

Aluminum (Al)

 

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

 

 

  Page Index
  • Expert Knowledge Explanations

 

Aluminum (Alo) 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 (Al
o) Metal
Al (2s) Spectrum – raw

Aluminum (Al
o) 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, Al2O
Peak-fits, BEs, FWHMs, and Peak Labels

 

Al (2p) from Al Native Oxide
on Aluminum metal

As-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 Al
2O
3
fresh exposed bulk
Charge Referenced to 285.0 eV



O (1s) from Al Native Oxide

on Aluminum metal
As-Measured


O (1s) from Al2O

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


 

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


 


Survey Spectrum of Aluminum Oxide (Al
2O3)
with Peaks Integrated, Assigned and Labelled

 

 Periodic Table 


 

Overlays of Al (2p) Spectra for
Alo 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 


 

Valence Band Spectra
Alo, Al2O3 

Alo metal   Al2O3

 

Overlay of Valence Band Spectra
for Alo metal and Al2O3  

Copyright ©:  The XPS Library

 Periodic Table 



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

 


 

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

 

 



 

Aluminum Minerals, Gemstones, and Chemical Compounds

 

Diaspore – AlOOH Spinel – MgAl2O4 Morganite – Be3Al2SiO6 AlF3

 Periodic Table 

 



 

 

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 

 



 

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 (2p3/2) 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 (2p3/2) 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 (2p3/2) BE = 932.62 eV and Au (4f7/2) 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 


Table #2

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

C (1s) BE = 284.8 eV

Copyright ©:  Ulvac-PHI


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


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


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
 

 

Histograms of NIST BEs from Al (2p)
NIST Database defines Adventitious Hydrocarbon C (1s) BE = 284.8 eV for all insulators.

Histogram indicates Al (2p) BE = 72.9 eV for Aluminum Metal (Al)
based on 15 literature BEs
Histogram indicates Al (2p) BE = 75.7 eV for Native Aluminum Oxide on top of Aluminum based on 18 literature BEs


Table #6

NIST Database of Al (2p) Binding Energies

NIST Standard Reference Database 20, Version 4.1

Data compiled and evaluated
by
Alexander V. Naumkin, Anna Kraut-Vass, Stephen W. Gaarenstroom, and Cedric J. Powell
©2012 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved.

Element Spectral Line Formula Energy (eV) Reference
Al 2p AlN 70.44  Click
Al 2p AlN 70.60  Click
Al 2p AlN 70.60  Click
Al 2p Al2O3 71.10  Click
Al 2p AlNiZr 71.80  Click
Al 2p AlNiY 72.00  Click
Al 2p O2/AlNiZr 72.00  Click
Al 2p O2/AlNiY 72.10  Click
Al 2p AlNiU 72.10  Click
Al 2p AlOx/Al 72.30  Click
Al 2p Al2O3/Al 72.30  Click
Al 2p AlP 72.43  Click
Al 2p Al 72.50  Click
Al 2p AlO1.63/Au 72.50  Click
Al 2p AlO1.46/(-C6H4C(CH3)2C6H4OC(O)O-)n 72.50  Click
Al 2p Al 72.70  Click
Al 2p AlAs 72.71  Click
Al 2p Al 72.80  Click
Al 2p Al 72.80  Click
Al 2p AlAs 72.80  Click
Al 2p AlAs 72.80  Click
Al 2p Al2O3/Al 72.80  Click
Al 2p Al2O3/Al 72.80  Click
Al 2p Al/AlOx 72.80  Click
Al 2p AlAs/GaAs 72.86  Click
Al 2p AlAs/GaAs 72.86  Click
Al 2p Al 72.90  Click
Al 2p AlOx/Al 72.90  Click
Al 2p AlOx/Al 72.90  Click
Al 2p Al2O3/Al 72.90  Click
Al 2p Al2O3/Al 72.90  Click
Al 2p Al2O3/Al 72.90  Click
Al 2p Al2O3/Al 72.90  Click
Al 2p CH3(CH2)17SiCl3/Al 72.90  Click
Al 2p Al/C 72.90  Click
Al 2p Al/Al2O3 72.90  Click
Al 2p Al90.7Cu7.9Fe1.4 72.90  Click
Al 2p Al2O3/Al 72.95  Click
Al 2p Al2O3/Al 73.00  Click
Al 2p Al2O3/Al 73.00  Click
Al 2p Al2O3/Al 73.00  Click
Al 2p Al2O3/Al 73.00  Click
Al 2p Al/O2 73.00  Click
Al 2p Al/SiO2/Mo 73.00  Click
Al 2p Al/Al2O3 73.00  Click
Al 2p Al/Al2O3 73.00  Click
Al 2p Al/Al2O3 73.00  Click
Al 2p Al70.5Mn6.4Pd23.1 73.00  Click
Al 2p AlO1.34/Au 73.00  Click
Al 2p AlO1.21/(-C6H4C(CH3)2C6H4OC(O)O-)n 73.00  Click
Al 2p Al78.9Mn3.8Pd17.3Ox 73.00  Click
Al 2p Al/AlOx 73.00  Click
Al 2p Al2O3/Al 73.02  Click
Al 2p AlN 73.10  Click
Al 2p Al2O3/Al 73.10  Click
Al 2p Al2O3/Al 73.10  Click
Al 2p Al72.1Mn6.9Pd21.0Ox 73.10  Click
Al 2p Al/(-CH2CH2-) 73.20  Click
Al 2p Al2O3/Al 73.24  Click
Al 2p AlSb 73.32  Click
Al 2p AlN1.1 73.50  Click
Al 2p AlN1.2 73.50  Click
Al 2p Pd/Al 73.60  Click
Al 2p Al4C3 73.60  Click
Al 2p (Na,Ca)0.5Fe1.0[Mg1.2Fe1.5Al2.3][Si6.8Al1.2O22](OH)2 73.60  Click
Al 2p Al2O3 73.62  Click
Al 2p Al2O3 73.62  Click
Al 2p Al0.3Ga0.7As 73.70  Click
Al 2p Al0.6Ga0.4As 73.70  Click
Al 2p Al0.6Ga0.4As 73.70  Click
Al 2p O2/Al0.6Ga0.4As 73.70  Click
Al 2p Na12[Al12Si12O48].18H2O 73.70  Click
Al 2p Zr[Al2.0O0.6(OH)1.4F2.3(H2O)1.4](C3H9N)0.7H0.5PO4)2.2.0H2O 73.70  Click
Al 2p Al2TiO5 73.70  Click
Al 2p Na11.9(AlO2)11.9(SiO2)12.1 73.70  Click
Al 2p (Ca1.6Mg0.4)[Mg2.0Fe1.9Al1.0][Si7.2Al0.8O22](OH,Cl) 73.70  Click
Al 2p (CH3)3Al/(-CH2C(OH)H-)n 73.72  Click
Al 2p AlNiYOx 73.80  Click
Al 2p (-Si(OCH3)2O-)xAly 73.80  Click
Al 2p K0.7(NaCa)0.3(Mg2.84Fe0.02)Al1.2Si2.8O10(OH1.5F0.50) 73.80  Click
Al 2p K0.7(NaCa)0.3(Mg2.84Fe0.02)Al1.2Si2.8O10(OH1.5F0.50) 73.80  Click
Al 2p Zr[Al1.0O0.3(OH)0.8F1.0(H2O)0.7](C3H9N)1.3H0.3(PO4)2.2.3H2O 73.80  Click
Al 2p Zr[Al3.4O1.1(OH)1.5F4.9(H2O)2.5](C3H9N)0.3H0.3PO4)2.2.9H2O 73.80  Click
Al 2p Na85.4(AlO2)85.4(SiO2)106.6 73.80  Click
Al 2p AlNiUOx 73.90  Click
Al 2p Al/(-CH2CH(C(O)OH)-)n 73.90  Click
Al 2p Al2O3 74.00  Click
Al 2p Al2O3 74.00  Click
Al 2p Al2O3 74.00  Click
Al 2p K0.9(Mg1.56Fe1.14Ti0.11)Al0.96Si3.0O10(OH1.44F0.56) 74.00  Click
Al 2p K0.9(Mg1.56Fe1.14Ti0.11)Al0.96Si3.0O10(OH1.44F0.56) 74.00  Click
Al 2p ZnAl2O4 74.00  Click
Al 2p Na7.5Al6Si6O24S4.5 74.05  Click
Al 2p Al2O3 74.10  Click
Al 2p Al2O3 74.10  Click
Al 2p Al2O3 74.10  Click
Al 2p Al2O3 74.10  Click
Al 2p MgAl2O4 74.10  Click
Al 2p O2/AlNiY 74.20  Click
Al 2p Al2O3 74.20  Click
Al 2p O2/AlNiZr 74.20  Click
Al 2p InAl6.5P0.4O13 74.20  Click
Al 2p (MgO)2(Al2O3)2(SiO2)5 74.20  Click
Al 2p Al(OH)3 74.20  Click
Al 2p NaAlSi2O6.H2O 74.20  Click
Al 2p (SiO2)55(CaO)21.5(Al2O3)14.5(B2O3)6.0(Na2O)0.8(MgO)0.6(Fe2O3)0.4(TiO2)0.3(F2)0.6(FO2)0.3(K2O)0.1 74.20  Click
Al 2p Al2O3 74.30  Click
Al 2p Al2O3 74.30  Click
Al 2p Al2O3 74.30  Click
Al 2p [(C2H5)2AlNNN]3 74.30  Click
Al 2p SiO2(Al2O3)0.22 74.30  Click
Al 2p MgAl2.7O5.3/SiO2 74.30  Click
Al 2p MgAl2.2O4.75 74.31  Click
Al 2p Al2O3 74.40  Click
Al 2p Al0.2Si0.8O2.2 74.40  Click
Al 2p Al2O3 74.40  Click
Al 2p Al2O3 74.40  Click
Al 2p MgAl2.3O4.8/SiO2 74.40  Click
Al 2p SiO2(Al2O3)0.22 74.40  Click
Al 2p AlPO4 74.40  Click
Al 2p Al(OH)3 74.40  Click
Al 2p H3Na45(AlO2)56(SiO2)136 74.40  Click
Al 2p Na69(NH4)13Al82Si110O384 74.40  Click
Al 2p Al2O3 74.45  Click
Al 2p MgAl2.2O4.75 74.45  Click
Al 2p Al2O3 74.50  Click
Al 2p Al2O3 74.50  Click
Al 2p AlNiZrOx 74.50  Click
Al 2p O2/AlNiU 74.50  Click
Al 2p WO3/Al2O3 74.50  Click
Al 2p Al2N6O2Si4 74.50  Click
Al 2p SiO2(Al2O3)0.55 74.50  Click
Al 2p SiO2(Al2O3)0.22 74.50  Click
Al 2p MgAl2.2O4.7/SiO2 74.50  Click
Al 2p Al3N5O3Si3 74.50  Click
Al 2p Al4N4O4Si2 74.50  Click
Al 2p AlN7OSi5 74.50  Click
Al 2p Al2Si2O5(OH)4 74.50  Click
Al 2p Al2Si2O5(OH)4 74.50  Click
Al 2p Na88Al86Si106O384 74.50  Click
Al 2p Na26.5H24.5Al51Si141O384 74.50  Click
Al 2p Na52(NH4)30Al82Si110O384 74.50  Click
Al 2p Na15(NH4)66Al82Si110O384 74.50  Click
Al 2p MgAl2.2O4.9 74.55  Click
Al 2p MgAl2O5 74.55  Click
Al 2p Al2O3 74.60  Click
Al 2p Al2O3 74.60  Click
Al 2p Al2O3 74.60  Click
Al 2p Al0.44Si0.41P0.13O2.1 74.60  Click
Al 2p K2WO4/Al2O3 74.60  Click
Al 2p SiO2(Al2O3)0.55 74.60  Click
Al 2p SiO2(Al2O3)0.55 74.60  Click
Al 2p AlOOH 74.60  Click
Al 2p Al0.041Si0.264Na0.04K0.02O0.635 74.60  Click
Al 2p H7Na41(AlO2)56(SiO2)136 74.60  Click
Al 2p Na60Al63Si128O384 74.60  Click
Al 2p Mg0.059Al0.126P0.158O0.635 74.60  Click
Al 2p H11Na37(AlO2)56(SiO2)136 74.60  Click
Al 2p (Na,Ca)0.5Fe1.0[Mg1.2Fe1.5Al2.3][Si6.8Al1.2O22](OH)2 74.60  Click
Al 2p Al0.54P0.45O2 74.60  Click
Al 2p Al2O3 74.70  Click
Al 2p SiO2(Al2O3)2.1 74.70  Click
Al 2p SiO2(Al2O3)2.1 74.70  Click
Al 2p Al2Si4O10(OH)2 74.70  Click
Al 2p Na54.5(AlO2)54.5(SiO2)137.5 74.70  Click
Al 2p (Ca1.6Mg0.4)[Mg2.0Fe1.9Al1.0][Si7.2Al0.8O22](OH,Cl) 74.70  Click
Al 2p Al2O3/Al 74.80  Click
Al 2p Al6Si2O13 74.80  Click
Al 2p H20Na28(AlO2)56(SiO2)136 74.80  Click
Al 2p AlOx/Al 74.90  Click
Al 2p O2/Al0.6Ga0.4As 74.90  Click
Al 2p Al2(SO4)3 74.90  Click
Al 2p O2/Al0.3Ga0.7As 74.90  Click
Al 2p O2/Al0.6Ga0.4As 74.90  Click
Al 2p O2/Al0.6Ga0.4As 74.90  Click
Al 2p Al2SiO5 74.90  Click
Al 2p NiAl2O4 74.90  Click
Al 2p Al2O3 75.00  Click
Al 2p Al0.35Si0.48P0.16O2.2 75.00  Click
Al 2p Al2(WO4)3 75.00  Click
Al 2p (CH3)3Al/Ag 75.00  Click
Al 2p AlO1.63/Au 75.10  Click
Al 2p AlO1.46/(-C6H4C(CH3)2C6H4OC(O)O-)n 75.10  Click
Al 2p [(CH3)2AlNNN]3 75.20  Click
Al 2p Al0.55Si0.10P0.35O2.2 75.20  Click
Al 2p Al0.52P0.48O2.2 75.50  Click
Al 2p AlO1.80/Au 75.50  Click
Al 2p Al72.1Mn6.9Pd21.0Ox 75.50  Click
Al 2p AlO1.77/(-C6H4C(CH3)2C6H4OC(O)O-)n 75.50  Click
Al 2p AlO1.72/Au 75.50  Click
Al 2p AlO1.47/(-C6H4C(CH3)2C6H4OC(O)O-)n 75.50  Click
Al 2p AlOx/Al 75.60  Click
Al 2p Al2O3/Al 75.60  Click
Al 2p Al2O3/Al 75.60  Click
Al 2p Al2O3/Al 75.60  Click
Al 2p Al2O3/Al 75.60  Click
Al 2p CH3(CH2)17SiCl3/Al 75.60  Click
Al 2p Al/Al2O3 75.60  Click
Al 2p AlO1.34/Au 75.60  Click
Al 2p AlO1.21/(-C6H4C(CH3)2C6H4OC(O)O-)n 75.60  Click
Al 2p Al2O3/Al 75.65  Click
Al 2p AlOx/Al 75.70  Click
Al 2p AlOx/Al 75.70  Click
Al 2p Al2O3/Al 75.70  Click
Al 2p Al2O3/Al 75.70  Click
Al 2p CaAl2O4 75.70  Click
Al 2p Al2O3/Al 75.75  Click
Al 2p Al2O3/Al 75.77  Click
Al 2p [(C2H5)2AlNH2]3 75.80  Click
Al 2p Al2O3/Al 75.80  Click
Al 2p Al2O3/Al 75.80  Click
Al 2p Al2O3/Al 75.80  Click
Al 2p Al2O3/Al 75.80  Click
Al 2p Al2O3/Al 75.80  Click
Al 2p Al2O3/Al 75.80  Click
Al 2p Al/O2 75.80  Click
Al 2p Al/SiO2/Mo 75.80  Click
Al 2p Al/Al2O3 75.80  Click
Al 2p Al/Al2O3 75.80  Click
Al 2p AlF2.3(OH)0.7.H2O 75.80  Click
Al 2p Al2O3 75.90  Click
Al 2p Al2O3/Al 75.90  Click
Al 2p Al/Al2O3 75.90  Click
Al 2p Al78.9Mn3.8Pd17.3Ox 75.90  Click
Al 2p Al2O3/Al 76.19  Click
Al 2p AlOx/Al 76.40  Click
Al 2p CoAl2O4 76.70  Click
Al 2p AlF3 76.90  Click
Al 2p AlF3 77.10  Click
Al 2p AlSb 79.92  Click
 
 
 
 
 
 
 
 
 

 

 

 



 

Advanced XPS Information Section

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

 

 


 

 

Statistical Analysis of Binding Energies in NIST XPS Database of BEs

 

 



 

 

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 


 

Overlay of
Al (2p) Spectra shown Above

C (1s) BE = 285.0 eV

 


 

Native Oxide on Aluminum Alo Metal
Naturally Formed at 25 Co 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


 

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)

 


 

Flood Gun Effect ExampleFeatures Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

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 


 

Valence Band Spectra Comparison
Alo,  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 

 



 
 
 
 
XPS Study of UHV Gases Captured by Freshly Ion Etched Aluminum
 
Reveals Chemical Shifts and Chemical States that Develop from Highly Reactive Pure Alo Metal

Surface was strongly Ar+ ion etched to remove all contaminants, and
then allowed to react overnight with the UHV Gases – CO, H2, H2O, O2 & CH4
that normally reside inside on the walls of the chamber, on the sample stage,
and on the nearby un-etched surface a total of 10-14 hours.  UHV pump was a Cryopump.
 
 
 
  .
Al (2p) Signal
 O (1s) Signal C (1s) Signal
     
 
 
Copyright ©:  The XPS Library


 

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  



 

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 



 

Information Useful for Peak-fitting Al (2p)

  • FWHM (eV) of Al (2p3/2) 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 (2p3/2) 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 


 

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 (3d5/2) FWHM (eV) = ~0.95 eV for PE 50 on Thermo K-Alpha
    • Ag (3d5/2) FWHM (eV) = ~1.00 eV for PE 80 on Kratos Nova
    • Ag (3d5/2) 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 


 

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 


 

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 


 

Data Collection Guidance

  • Chemical state differentiation can be difficult
  • To record the 0.4 eV splitting between Al (2p3/2) and Al (2p1/2), 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 


 

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 (3d5/2) 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 


 

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 

 


 

Gas Phase XPS or UPS Spectra
 

 
 
 


 
 
 
Chemical State Spectra for Al (2p) Published in the Literature
 
from Thermo Scientific website
 
 



End of File