Auger Parameter Video

Video explaining the use of the Auger parameter.

Fluorine

F 1s binding energy values.

Notes: [1] lists -CH2CHFCH2- (PVF) at 686.94 eV, (-CF2-CF2-)n (PTFE) at 689.67 eV, and OOCCF3 (PVTFA) at 688.16 eV.

F 2s: 30 eV

Reference:
[1]  G. Beamson, D. Briggs, High Resolution XPS of Organic Polymers - The Scienta ESCA300 Database Wiley Interscience, 1992.

Advanced Analysis of Gallium Compounds

Work by Jeremy Bourque [1] demonstrates the power of XPS to elucidate chemical trends within a series of compounds.  This work shows results from an extensive analysis of the Ga 3d5/2, Ga 2p3/2 and Ga L3M45M45 spectra of a broad series of Ga compounds.  Binding energy positions, Auger parameters and chemical state (Wagner) plots are then used to understand the trends found for the various series of related compounds and to understand the chemistry of newly synthesized complexes.  Examples of studied trends include the changes as the oxidation states goes from Ga(0) through to Ga(III), changes as the ligand is modified on Ga(I) or Ga(III) species, and trends in the various semiconducting Ga materials.  This work has been applied to more compounds in [2].


Photoelectron binding and Auger electron kinetic energies and full-width at half-maxima for high-resolution XPS spectra along with associated Auger Parameters.

  Ga 3d (left), Ga 2p3/2 (center) and Ga L3M45M45 (right) XPS spectra of Ga(m) (bottom), GaNacNacDipp (lower middle), Ga2Cl4(diox)2 (upper middle) and GaCl3 (top).



Ga 3d (left), Ga 2p3/2 (center) and Ga L3M45M45 (right) XPS spectra of GaCl3 (bottom), GaBr3 (middle) and GaI3 (top).



Wagner plot of gallium materials using Ga 3d5/2 binding energy. Symbol legend: diamond = Group 15 elements; square = Group 16 elements.

Reference:

[1] J.L. Bourque, M.C. Biesinger, K.M. Baines, Dalton Transactions, 45 (2016) 7678-7696.

[2] J.L. Bourque, R.A. Nanni, M.C. Biesinger, K.M. Baines, Inorganic Chemistry, 60 (2021) 14713-14720.

Mn 3s Peak Separation Values

In addition to curve-fitting of the Mn 2p spectrum, the Mn 3s peak (if available) can also provide useful insight into the Mn oxidation state of an unknown sample.  The Mn 3s peak is split into two peaks and the peak separation may be used to elucidate oxidation state.  Peak separation ranges are presented below. 

From [1] for oxides.
Mn(II) 5.7-6.2 eV
Mn(III) 4.6-5.4 eV (4.6 for MnOOH, Mn2O3 selected values were  5.2-5.4 eV)
Mn(IV) 4.5-4.7 eV

The trends are less convincing when you look at a wider set of data that includes various other ligands[2].  The ligand-Mn bond degree of covalency effects the peak separation [1,3]. Use caution when other Mn compounds are possible.
Mn(0) 3.7-4.2 eV
MnO 5.5-6.1 eV
MnOOH 4.6 eV
Mn2O3 5.4-5.5 eV
Mn3O4 5.3-5.4 eV
MnO2 4.5-5.5 eV
MnF2 6.3-6.5 eV
MnF3 5.6 eV
MnS 5.3 eV
MnS2 5.5 eV
MnCl2 6.0 eV
MnBr2 4.8 eV

As recent article from Eugene Ilton[4] tests of the use of the Mn 3s splitting values as a means to determine oxidation state and shows it to be not of great value (i.e. doubt is cast on its usefulness).

References:
[1] J.L. Junta, M.F. Hochella Jr., Geochimca et Cosmochimica Acta, 58 (1994) 4985-4999.
[2] C.D. Wagner, A.V. Naumkin, A. Kraut-Vass, J.W. Allison, C.J. Powell, J.R.Jr. Rumble, NIST Standard Reference Database 20, Version 3.4 (web version) (http:/srdata.nist.gov/xps/) 2003.
[3] A.J. Nelson, J.G. Reynolds, J.W. Roos, J. Vac. Sci. Technol. A 18(4) (2000) 1072-1076.
[4] E.S. Ilton, J.E. Post, P.J. Heaney, F.T. Ling, Appl. Surf. Sci. 366 (2016) 475.

Sodium

Na 1s binding energy and Na 1s-KL23L23(1D) Auger parameter values [1].

Reference:

[1] C.D. Wagner, A.V. Naumkin, A. Kraut-Vass, J.W. Allison, C.J. Powell, J.R.Jr. Rumble, NIST Standard Reference Database 20, Version 3.4 (web version) (http:/srdata.nist.gov/xps/) 2003.

Rhodium

Rh 3d5/2 binding energy values [1].

Rh 3d XPS spectrum of sputter cleaned rhodium metal.

Peakshape from metal standard in figure above is LA(1.2,3,2). FWHMs are 0.51 eV (3d5/2) and 0.79 eV (3d3/2) at 10 eV pass energy and 0.56 eV (3d5/2) and 0.82 eV (3d3/2) at 20 eV pass energy. Note some broadening of 3d3/2 peak versus 3d5/2 peak due to Coster-Kronig effect.

Rh 3d5/2-3d3/2 splitting is 4.71 eV [2].
Rh 3p3/2: 497 eV
Rh 3p1/2: 512 eV
Rh 3s: 629 eV
Rh 4p: 48 eV
Rh 4s: 81 eV

References:
[1] C.D. Wagner, A.V. Naumkin, A. Kraut-Vass, J.W. Allison, C.J. Powell, J.R.Jr. Rumble, NIST
Standard Reference Database 20, Version 3.4 (web version) (http:/srdata.nist.gov/xps/) 2003.
[2] J.F. Moulder, W.F. Stickle, P.E. Sobol, K.D. Bomben, Handbook of X-ray Photoelectron Spectroscopy, Perkin-Elmer Corp., Eden Prairie, MN, 1992.

Advanced Quantification Combining Survey Scan and High Resolution Data

Using a combination of the results from survey scans and fitted high resolution data one can, using relatively simple math, develop a clear picture of the different species on a surface.  Recent work [1,2] highlights this and will be used as an example below.

A series of oxide films of Ni-Cr-Mo alloys (corrosion resistant alloys in both oxidizing and reducing environments) where analysed by XPS.  Survey scans (how to quantify here) and high resolution scans of the Ni 2p, Cr 2p, Mo 3d, O 1s and C 1s peaks were taken and the various chemical states determined and quantified using the curve-fitting procedures from [3-5] and [6].


Figure 1. XPS survey spectrum recorded on C22 after polarization at 0 V (+) in a pH = 7 solution.

Figure 2. Surface composition (normalized) obtained from the survey spectra of (a) C22 and (b) BC1 alloy after polarization at, 0 V and 0.5 V (positive scan) and 0 V and -0.4 V (negative scan) at pH = 7 solution. (The small amount of adventitious carbon has been factored out of these quantifications.)  

Carbon, which was mainly present as a small amount of adventitious carbon, has been simply factored out of the quantification in this case.  In cases where carbon plays a bigger role or is part of the species of interest one must include it in the calculations.  For example, if you want to calculate the contribution of carbonaceous oxygen in the O 1s spectrum you can use this calculator.


Figure 3. High-resolution deconvoluted XPS spectra for (a) O 1s, (b) Ni 2p, (c) Cr 2p and (d) Mo 3d collected on C22 at 0 V (+) and pH = 7.

These deconvoluted spectra will give us the percentage of each species as a function of each element. For example, 70% of the total Cr is present as Cr(OH)3, 20 % as Cr2O3 and 10 % as Cr metal.


Figure 4. Normalized relative film composition (%) of Ni, Cr and Mo and their relative metal, oxide, hydroxide components present in films polarized at specific potentials for (a) C22 and (b) BC1 alloy.

In Figure 4 the percentages of each oxide and metal species, from the high resolution data, has been combined with the amounts of each element in the survey scan data to give us a full picture of the amount of each species present at the surface of these films.

Caveat: Depth effects have not been accounted for here. Further work using Auger and/or XPS depth profiling, angle resolved analysis or QUASES analysis can help to further clarify the positions of various species. It is of course assumed here that the metal detected is from the underlying alloy.

References:
[1] Ebrahimi, Nafiseh, "The Influence of Alloying Elements on The Crevice Corrosion Behaviour of Ni-Cr-Mo Alloys" (2015). Electronic Thesis and Dissertation Repository. 3316.  http://ir.lib.uwo.ca/etd/3316
[2] N. Ebrahami, M.C. Biesinger,D.W. Shoesmith, J.J. Noel, The Influence of Chromium and Molybdenum on the Repassivationof Nickel-Chromium-Molybdenum Alloys in Saline Solutions, Surface and Interface Analysis, 49 (2017) 1359.
[3] M.C. Biesinger, B.P. Payne, A.P. Grosvenor, L.W. Lau, A.R. Gerson, R.St.C. Smart, Appl. Surf. Sci. 257 (2011) 2717.
[4] M.C. Biesinger, B.P. Payne, L.W. Lau, A.R. Gerson, R.St.C. Smart, Surf. Interface Anal. 41 (2009) 324.
[5] M.C. Biesinger, C. Brown, J.R. Mycroft, R.D. Davidson, N.S. McIntyre, Surf. Interface Anal. 36 (2004) 1550.
[6] P. Spevack, N.S. McIntyre, J. Phys. Chem. 96 (1992) 9029.

Oxygen 1s Curve-Fitting Video

Video showing curve-fitting of the oxygen 1s (O 1s) spectrum for metallic surfaces using CasaXPS.

Titanium 2p Curve-Fitting Video

Video showing curve-fitting of the titanium 2p (Ti 2p) XPS spectrum using CasaXPS.



Chromium 2p3/2 Curve-Fitting Video

Video showing curve-fitting of the chromium (Cr 2p3/2) XPS spectrum using CasaXPS.