Wo WO3 WS2 WN WC CaWO4 CdWO4 Li2WO4 Na2WO4 WB

Basic XPS Information Section

The Basic XPS Information Section provides fundamental XPS spectra, BE values, FWHM values, BE tables, overlays of key spectra, 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.
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Tungsten (W)
(Wolfram)

Atolzite – Pb(WO4) Tungsten – Wo Ferberite – Fe(WO4)

 

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  • Expert Knowledge & Explanations


Tungsten (Wo) Metal

Peak-fits, BEs, FWHMs, and Peak Labels


Tungsten (Wo) Metal
W (4f) Spectrum – raw spectrum
Tungsten (Wo) Metal
Peak-fit of W (4f Spectrum (w/o asymm)
→  Periodic Table – HomePage  
Tungsten (Wo) Metal
W (4f) Spectrum – extended range 
 Tungsten (Wo) Metal
Peak-fit of W (4f) Spectrum (w asymm)
 

 .
Tungsten (Wo) Metal
W (4d) Spectrum		 Tungsten (Wo) Metal
W (4p) Spectrum
 

Survey Spectrum of Tungsten (Wo) Metal
with Peaks Integrated, Assigned and Labelled

 

 
→  Periodic Table 

XPS Signals for Tungsten (Wo) 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
W (4s) 594 1.81 13.9
Sn (3d) overlaps W (4p1/2) 490 2.12 15.7
W (4p3/2) 423 5.30 15.7
Br (3s) overlaps W (4d3/2) 256 6.95 17.7
Ar (2p) overlaps W (4d5/2) 243 10.06 17.7
W (4f5/2) 33.40 4.88 19.8
F (2s) overlaps W (4f7/2) 31.22 6.20 19.8
Al (2p) & Cu (3p) overlap W (5s) 75 0.402 19.4
As (3d) overlaps W (5p1/2) ~47 0.387 19.8

σ:  abbreviation for the term Scofield Photoionization Cross-Section which is used with IMFP and TF to generate RSFs and atom% quantitation

Plasmon Peaks

Auger Peaks

 Plasmon Peak:  ~xx eV above peak max
Expected Bandgap for WO3:  2.6-3.0 eV
Work Function for W:  xx eV

*Scofield Cross-Section (σ) for C (1s) = 1.0

→  Periodic Table 

 

Valence Band Spectrum from Wo Metal
 Fresh exposed bulk produced by extensive Ar+ ion etching

 

 

Plasmon Peaks from Wo Metal
 Fresh exposed bulk produced by extensive Ar+ ion etching

W (4f) – Extended Range Spectrum W (4f) – Extended Range Spectrum – Vertically Zoomed
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W (MNN) Auger Peaks from Wo Metal
 Fresh exposed bulk produced by extensive Ar+ ion etching
Wo Metal – main Auger peak Wo Metal – full Auger range
 

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 


Artefacts Caused by Argon Ion Etching

C (1s) from Tungsten Carbide(s)

can form when ion etched Reactive Metal Surfaces capture
Residual UHV Gases (CO, H2O, CH4 etc)

Argon Trapped in Wo

can form when Argon Ions are used
to removed surface contamination
 

Side-by-Side Comparison of

W Native Oxide & Tungsten Oxide (WO3)
Peak-fits, BEs, FWHMs, and Peak Labels
W Native Oxide WO3
W (4f) from W Native Oxide
Flood Gun OFF
As-Measured, C (1s) at 284.9 eV 		 W (4f) from WO3 – pressed powder
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 
→  Periodic Table   
W Native Oxide WO3
C (1s) from W Native Oxide
As-Measured, C (1s) at 284.9 eV (Flood Gun OFF)

C (1s) from WO3 – pressed powder
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV
 

→  Periodic Table   
W Native Oxide WO3
O (1s) from W Native Oxide
As-Measured, C (1s) at 284.9 eV (Flood Gun OFF)

O (1s) from WO3 – pressed powder
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

→  Periodic Table

 

 


Survey Spectrum of Tungsten (W) Native Oxide
with Peaks Integrated, Assigned and Labelled

 

→  Periodic Table 

 

 

Survey Spectrum of Tungsten Oxide (WO3)
with Peaks Integrated, Assigned and Labelled

 

 

→  Periodic Table  

Overlays of W (4f) Spectra for
W Native Oxide and WO3

Caution: BEs from Grounded Native Oxides can be Misleading if Flood Gun is ON

 Overlay of Wo metal and W Native Oxide – W (4f)
Native Oxide C (1s) = 284.9 eV (Flood gun OFF)

  Overlay of Wo metal and WO3 – W (4f)
Pure Oxide C (1s) = 285.0 eV
Chemical Shift: 4.6 eV
→  Periodic Table  Copyright ©:  The XPS Library 

 

Overlay of W (4f)
Wo Metal, W Native Oxide, & WO3  

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

Valence Band Spectra
Wo, WO3

Wo
Ion etched clean		 WO3 – pressed pellet
Flood gun is ON,  Charge referenced so C (1s) = 285.0 eV

Overlay of Valence Band Spectra
for Wo metal and WO3

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

Tungsten Minerals, Gemstones, and Chemical Compounds

 
Hubnerite – MnWO4 Raspite – Pb(WO4) Chillagite – Pb(WO4) Scheelite – Ca(WO4)

→  Periodic Table 

 

Six (6) Chemical State Tables of W (4f7/2) 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
  • 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 between 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

W (4f7/2) 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
W 74 W (N*12) 31.1 eV 31.6 eV 284.8 eV Avg BE – NIST
W 74 W-B 31.3 eV 285.0 eV The XPS Library
W 74 W – element 31.4 eV 285.0 eV The XPS Library
W 74 W-N0.23 (N*1) 31.4 eV 284.8 eV Avg BE – NIST
W 74 WO2 (N*7) 31.4 eV 34.2 eV 284.8 eV Avg BE – NIST
W 74 WC (N*3) 31.5 eV 32.2 eV 284.8 eV Avg BE – NIST
W 74 W-S2 (N*3) 31.6 eV 33.2 eV 284.8 eV Avg BE – NIST
W 74 W-C 31.7 eV 32.3 eV 285.0 eV The XPS Library
W 74 W-O2 32.4 eV 32.6 eV 285.0 eV The XPS Library
W 74 W-S2 32.7 eV 285.0 eV The XPS Library
W 74 CaWO4 (N*2) 34.9 eV 35.1 eV 284.8 eV Avg BE – NIST
W 74 Na2WO4 35.2 eV 285.0 eV The XPS Library
W 74 WO3 (N*15) 35.2 eV 36.6 eV 284.8 eV Avg BE – NIST
W 74 H2WO4 (N*2) 35.3 eV 36.2 eV 284.8 eV Avg BE – NIST
W 74 W-O3 35.5 eV 37.0 eV 285.0 eV The XPS Library
W 74 Li2WO4 35.6 eV 285.0 eV The XPS Library
W 74 Na2W2O7 35.6 eV 285.0 eV The XPS Library
W 74 CaWO4 35.7 eV 285.0 eV The XPS Library
W 74 Li2WO4 (N*2) 35.9 eV 36.0 eV 285.0 eV The XPS Library
W 74 W-Cl6 (N*3) 36.0 eV 36.6 eV 284.8 eV Avg BE – NIST
W 74 WOCl4 (N*2) 37.2 eV 284.8 eV Avg BE – NIST

 

Charge Referencing Notes

  • (N*number) identifies the number of NIST BEs that were averaged to produce the BE in the middle column.
  • The XPS Library uses Binding Energy Scale Calibration with 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 (1s) 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

W (4f7/2) Chemical State BEs from:  “PHI Handbook”

C (1s) BE = 284.8 eV

→  Periodic Table 

Copyright ©:  Ulvac-PHI

Table #3

W (4f7/2) Chemical State BEs from:  “Thermo-Scientific” Website

C (1s) BE = 284.8 eV

Chemical state Binding energy (eV),
W (4f7/2)
W metal 31.6
WS2 32.4
WO2 33.1
WO3 36.1

→  Periodic Table 

Copyright ©:  Thermo Scientific 

Table #4

W (4f7/2) 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

→  Periodic Table 

Copyright ©:  Mark Beisinger

Table #5

W (4f7/2) Chemical State BEs from:  “Techdb.podzone.net” Website

 

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

XPS(X線光電子分光法)スペクトル 化学状態 化学シフト ケミカルシフト

Element Level Compound B.E.(eV) min max
W 4f7/2 W 31.5 ±0.3 31.2 ～ 31.8
W 4f7/2 WC 31.8 ±0.4 31.4 ～ 32.2
W 4f7/2 Ph3PW(CO)5 32.0 ±0.8 31.2 ～ 32.8
W 4f7/2 Cl3SnW(CO)3(C5H5) 32.4 ±0.2 32.2 ～ 32.6
W 4f7/2 WS2 33.3 ±0.3 33.0 ～ 33.5
W 4f7/2 Oxides 34.3 ±1.5 32.8 ～ 35.8
W 4f7/2 Cl4W(Et3P)2 34.6 ±0.3 34.3 ～ 34.8
W 4f7/2 Rh2WO6 35.6 ±0.3 35.3 ～ 35.8
W 4f7/2 Tungstate 35.7 ±0.7 35.0 ～ 36.4
W 4f7/2 Halides 36.4 ±0.6 35.8 ～ 36.9
W 4f7/2 WOCl4 37.3 ±0.3 37.0 ～ 37.6

 

→  Periodic Table 

 
 

Histograms of NIST BEs for W (4f7/2) BEs

Important Note:  NIST Database defines Adventitious Hydrocarbon C (1s) BE = 284.8 eV for all insulators.

Histogram indicates:  31.35 eV for Wo based on 13 literature BEs Histogram indicates:  35.9 eV for WO3 based on 13 literature BEs

Histogram indicates:  31.9 eV for WC based on 3 literature BEs

Table #6


NIST Database of W (4f7/2) 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.

Important Note:  NIST Database defines Adventitious Hydrocarbon C (1s) BE = 284.8 eV for all insulators.

 

Element Spectral Line Formula Energy (eV) Reference
W 4f7/2 [(N(C2H5)4)W(CO)5]Cl 30.00  Click
W 4f7/2 [W(CO)2((C6H5)2PCH2CH2P(C6H5)2)2] 30.20  Click
W 4f7/2 WGe2 30.20  Click
W 4f7/2 [W(CO)2(CH3CN)(PCH3(C6H5)2)3] 30.40  Click
W 4f7/2 [WH4(P(CH3)2(C6H5))4] 30.50  Click
W 4f7/2 [W(CO)2((C6H5)2PCH2CH2P(C6H5)2)2] 30.50  Click
W 4f7/2 [W(CO)5(C5H5N)] 30.50  Click
W 4f7/2 W(N2)2((C6H5)2CH2CH2P(C6H5)2)2 30.50  Click
W 4f7/2 [WH4((C4H9)P(C6H5)2)4] 30.60  Click
W 4f7/2 [WH4((C6H5)2PCH3)4] 30.60  Click
W 4f7/2 [WH4(P(CH3C2H5O)3)4] 30.60  Click
W 4f7/2 [W(N2)2((C6H5)2PCH2CH2P(C6H5)2)] 30.60  Click
W 4f7/2 [WH4(PH(C6H5)2)4] 30.70  Click
W 4f7/2 W6S8(C5H11N)6 30.70  Click
W 4f7/2 W6S8(C5H5N)6 30.70  Click
W 4f7/2 WGe2 30.70  Click
W 4f7/2 [W(CO)3(PCH3(C6H5)2)3] 30.80  Click
W 4f7/2 [W2(CO)4((C6H5)2PCH2CH2P(C6H5)2)3] 30.80  Click
W 4f7/2 W 30.90  Click
W 4f7/2 W5Ge3 30.90  Click
W 4f7/2 [W(CO)4((C6H5)2PCH2CH2P(C6H5)2)] 31.00  Click
W 4f7/2 W 31.00  Click
W 4f7/2 W 31.00  Click
W 4f7/2 W6Se8(C5H5N)6 31.00  Click
W 4f7/2 W6Se8(C5H11N)6 31.00  Click
W 4f7/2 W5Ge3 31.00  Click
W 4f7/2 W 31.09  Click
W 4f7/2 [W(CO)4(P(C6H5)3)2] 31.10  Click
W 4f7/2 W 31.10  Click
W 4f7/2 W 31.15  Click
W 4f7/2 S/W 31.19  Click
W 4f7/2 [WCl(CO)2(CH3C3H4)(C5H4N)2] 31.20  Click
W 4f7/2 [WBr(CO)2(C3H5)(NC5H4C5H4N)] 31.20  Click
W 4f7/2 W 31.20  Click
W 4f7/2 W 31.20  Click
W 4f7/2 [W(CO)4((C4H9)P(C6H5)2)2] 31.30  Click
W 4f7/2 [WCl(CO)2(C3H5)(NC5H4C5H4N)] 31.30  Click
W 4f7/2 BaO/W 31.30  Click
W 4f7/2 WF6/W 31.30  Click
W 4f7/2 WF6/W 31.30  Click
W 4f7/2 W 31.32  Click
W 4f7/2 W 31.33  Click
W 4f7/2 S/W 31.33  Click
W 4f7/2 S/W 31.33  Click
W 4f7/2 W 31.34  Click
W 4f7/2 WOx/W 31.37  Click
W 4f7/2 [W(CO)2(C5H5)(NC(CH3C6H4)2)] 31.40  Click
W 4f7/2 [W(C3H5)(CO)2(CH3COO)(NC5H4C5H4N)] 31.40  Click
W 4f7/2 [W(CO)5((C6H5)3P)] 31.40  Click
W 4f7/2 WO2 31.40  Click
W 4f7/2 W 31.40  Click
W 4f7/2 W 31.40  Click
W 4f7/2 W 31.40  Click
W 4f7/2 W 31.40  Click
W 4f7/2 WN0.23 31.40  Click
W 4f7/2 W(CO)6/Ni 31.40  Click
W 4f7/2 W/WO3 31.40  Click
W 4f7/2 W 31.41  Click
W 4f7/2 H2/W 31.41  Click
W 4f7/2 H2/W 31.41  Click
W 4f7/2 H2/W 31.41  Click
W 4f7/2 H2/W 31.41  Click
W 4f7/2 W 31.42  Click
W 4f7/2 W 31.44  Click
W 4f7/2 S/W 31.44  Click
W 4f7/2 S/W 31.44  Click
W 4f7/2 W 31.47  Click
W 4f7/2 WC 31.50  Click
W 4f7/2 [W(CO)2(C5H5)(F3CC6H4C(N)C6H4CF3)] 31.50  Click
W 4f7/2 W 31.50  Click
W 4f7/2 W 31.50  Click
W 4f7/2 CO2/BaO/W 31.50  Click
W 4f7/2 O2/BaO/W 31.50  Click
W 4f7/2 S/W 31.51  Click
W 4f7/2 S/W 31.51  Click
W 4f7/2 [W(CO)5((C6H5)3P)] 31.55  Click
W 4f7/2 W(CO)6/Ni 31.55  Click
W 4f7/2 [WH6((CH3)2P(C6H5))3] 31.60  Click
W 4f7/2 [W(Cl2)H2((C6H5)2PCH2CH2P(C6H5)2)] 31.60  Click
W 4f7/2 WS2 31.60  Click
W 4f7/2 W 31.60  Click
W 4f7/2 W 31.60  Click
W 4f7/2 H2O/BaO/W 31.60  Click
W 4f7/2 [W(CO)5(As(C6H5)3)] 31.65  Click
W 4f7/2 WSe2 31.65  Click
W 4f7/2 WSe2 31.65  Click
W 4f7/2 [W2(CO)10(N2H2)] 31.70  Click
W 4f7/2 O2/W 31.70  Click
W 4f7/2 W(CO)6/Ni 31.70  Click
W 4f7/2 W(CO)5(C5H4P(C6H5)2)2Fe 31.70  Click
W 4f7/2 [W(CO)5(Sb(C6H5)3)] 31.72  Click
W 4f7/2 WSe2 31.75  Click
W 4f7/2 WSe2 31.75  Click
W 4f7/2 WC 31.80  Click
W 4f7/2 [WCl(CO)2((C6H5)2PCH2CH2P(C6H5)2)(C3H5)] 31.80  Click
W 4f7/2 O2/W 31.80  Click
W 4f7/2 W(CO)5(C5H4P(C6H5)2)2FeW(CO)5 31.80  Click
W 4f7/2 O2/WC 31.80  Click
W 4f7/2 WCl(N)((C6H5)2CH2CH2P(C6H5)2)2 31.80  Click
W 4f7/2 [W(CO)5(NH3)] 31.90  Click
W 4f7/2 [W(CO)3(SnCl(CH3)2)(C5H5)] 31.90  Click
W 4f7/2 [WCl(NNH2)((C6H5)2CH2CH2P(C6H5)2)2]Cl 31.90  Click
W 4f7/2 [W(CO)5(N2H4)] 32.00  Click
W 4f7/2 [W2(CO)10(N2H4)] 32.00  Click
W 4f7/2 WC 32.00  Click
W 4f7/2 WC 32.00  Click
W 4f7/2 O2/W 32.00  Click
W 4f7/2 MoWCl4(P(CH3)3)4 32.00  Click
W 4f7/2 [W(CO)3(C5H5)(Sn(CH3)3)] 32.10  Click
W 4f7/2 [W(CO)3(CH3)(C5H5)SnCl2] 32.10  Click
W 4f7/2 WS2 32.10  Click
W 4f7/2 Li1.76WS3 32.10  Click
W 4f7/2 Li0.85WS3 32.10  Click
W 4f7/2 WC 32.20  Click
W 4f7/2 [NH4]10[W12O41] 32.20  Click
W 4f7/2 W2(mu-H)(mu-Cl)Cl4(C2H5C5H5N)4 32.20  Click
W 4f7/2 WSe2 32.30  Click
W 4f7/2 WSe2 32.30  Click
W 4f7/2 [W(CO)3(C5H5)]SnCl3 32.40  Click
W 4f7/2 W2(mu-H)(mu-Cl)Cl4(C5H5N)4 32.40  Click
W 4f7/2 Li0.2WS3 32.40  Click
W 4f7/2 [WBr(NNH2)((C6H5)2CH2CH2P(C6H5)2)2]Br 32.40  Click
W 4f7/2 WSe2 32.50  Click
W 4f7/2 WSe2 32.50  Click
W 4f7/2 [W(CO)3(Sn(C6H5)3)(C5H5)] 32.60  Click
W 4f7/2 W6Cl12 32.60  Click
W 4f7/2 WO2 32.70  Click
W 4f7/2 WO2 32.70  Click
W 4f7/2 WO2 32.70  Click
W 4f7/2 WSe2 32.70  Click
W 4f7/2 WSe2 32.70  Click
W 4f7/2 WSe2 32.70  Click
W 4f7/2 WSe2 32.70  Click
W 4f7/2 [WCl(NH)((C6H5)2CH2CH2P(C6H5)2)2]Cl 32.70  Click
W 4f7/2 WS2 32.80  Click
W 4f7/2 WO2 32.90  Click
W 4f7/2 WS2 32.90  Click
W 4f7/2 WO2 33.00  Click
W 4f7/2 WS3 33.10  Click
W 4f7/2 W6Ni2S16O62C56H132 33.10  Click
W 4f7/2 WS2 33.20  Click
W 4f7/2 WS2 33.20  Click
W 4f7/2 ((C2H5)4N)2[(SC=(C(O)C6H5)C(C(O)C6H5)S)W(O)(muS)2W(O)(SC=(C(O)C6H5)C(C(O)C6H5)S)] 33.20  Click
W 4f7/2 ((CH3)4N)2[W2O2S2(S2)(S4)] 33.20  Click
W 4f7/2 ((CH3)2NH2)6[(SCN)9W3S4SnCl3].0.5H2O 33.20  Click
W 4f7/2 WMo2NiS8O29C28H62 33.30  Click
W 4f7/2 WO2 33.40  Click
W 4f7/2 W2S2(S2)(S2CN(C2H5)2)2 33.40  Click
W 4f7/2 Li1.76WS3 33.40  Click
W 4f7/2 Na2[W2(O)2(muS)2(mu(O(O)CCH2)2NCH2CH2N(CH2C(O)O))] 33.50  Click
W 4f7/2 Na2[W2(O)2(muO)(muS)(mu(O(O)CCH2)2NCH2CH2N(CH2C(O)O))] 33.50  Click
W 4f7/2 ((C6H5)4P)2[W2O2S2(S4)2] 33.60  Click
W 4f7/2 MoW2S4(H2O)9(CH3C6H4SO3)4.9H2O 33.60  Click
W 4f7/2 W3S4(H2O)9(CH3C6H4SO3)4.9H2O 33.60  Click
W 4f7/2 ((C2H5)4N)2[W2O2S2(S4)2] 33.60  Click
W 4f7/2 WCl4 33.60  Click
W 4f7/2 [WCl4(P(C6H5)3)2] 33.70  Click
W 4f7/2 W2O2(S2)(S2CN(C2H5)2)2 33.70  Click
W 4f7/2 ((C2H5)4N)2[S2W(O)(muS)2W(O)S2] 33.70  Click
W 4f7/2 (N(C4H9)4)3W(CN)8 33.70  Click
W 4f7/2 (NH4)2WS4 33.70  Click
W 4f7/2 Mo2WS4(H2O)9(CH3C6H4SO3)4.9H2O 33.80  Click
W 4f7/2 Na2[W(O)W(O)(muO)(muO)(mu(O(O)CCH2)2NCH2CH2N(CH2C(O)O)2)] 34.10  Click
W 4f7/2 Na2[W(O)W(O)(muO)(muO)(mu(O(O)CCH2)2NCH2CH2N(CH2C(O)O)2)] 34.10  Click
W 4f7/2 Na2[W(O)W(O)(muO)(muO)(mu(O(O)CCH2)2NCH2CH2N(CH2C(O)O)2)] 34.10  Click
W 4f7/2 Li0.85WS3 34.10  Click
W 4f7/2 WO2 34.20  Click
W 4f7/2 [WCl2(O)(P(C2H5)3)(CH2C(CH3)2)CH2] 34.30  Click
W 4f7/2 W18O49 34.30  Click
W 4f7/2 [W3O2(CH3C(O)O)6(H2O)3]Br2 34.30  Click
W 4f7/2 [MoW2O2(CH3C(O)O)6(H2O)3]Br2 34.40  Click
W 4f7/2 (P(C6H5)4)2W(CN)6O 34.40  Click
W 4f7/2 BaWO4 34.50  Click
W 4f7/2 [WCl4(P(C2H5)3)2] 34.60  Click
W 4f7/2 Li0.2WS3 34.60  Click
W 4f7/2 [NH4]10[W12O41] 34.80  Click
W 4f7/2 Na2[Mo(O)W(O)(muO)2(mu(O(O)C)2NCH2CH2N(C(O)O)2)] 34.80  Click
W 4f7/2 Na2[Mo(O)W(O)(muO)2(mu(O(O)CCH2)2NCH2CH2N(CH2C(O)O))] 34.80  Click
W 4f7/2 WCl4 34.90  Click
W 4f7/2 K2[WCl6] 34.90  Click
W 4f7/2 WO3 34.90  Click
W 4f7/2 WO3 34.90  Click
W 4f7/2 CaWO4 34.90  Click
W 4f7/2 [WCl3(O)(P(C2H5)3)2] 35.00  Click
W 4f7/2 [NH4]10[W12O41] 35.00  Click
W 4f7/2 Ag2WO4 35.00  Click
W 4f7/2 [Mo2WO2(CH3C(O)O)6(H2O)3]Br2 35.00  Click
W 4f7/2 Ag2WO4 35.00  Click
W 4f7/2 (Li2O)0.50(P2O5)0.45(WO3)0.05 35.00  Click
W 4f7/2 CaWO4 35.10  Click
W 4f7/2 Na2WO4 35.10  Click
W 4f7/2 Na2WO4 35.10  Click
W 4f7/2 WO3 35.20  Click
W 4f7/2 WO3 35.20  Click
W 4f7/2 WO3 35.20  Click
W 4f7/2 (Li2O)0.50(P2O5)0.30(WO3)0.20 35.20  Click
W 4f7/2 (Li2O)0.50(P2O5)0.35(WO3)0.15 35.20  Click
W 4f7/2 H2WO4 35.30  Click
W 4f7/2 (NH4)2WO4 35.30  Click
W 4f7/2 (NH4)2WO4 35.30  Click
W 4f7/2 WS3 35.30  Click
W 4f7/2 C24H18N4(H4SiW12O40)0.06 35.30  Click
W 4f7/2 NiWO4 35.40  Click
W 4f7/2 Li2WO4 35.40  Click
W 4f7/2 WO3 35.40  Click
W 4f7/2 Li2WO4 35.40  Click
W 4f7/2 WO3 35.40  Click
W 4f7/2 (Li2O)0.50(P2O5)0.40(WO3)0.10 35.40  Click
W 4f7/2 C12H8S8[W6O19] 35.40  Click
W 4f7/2 [WCl3(OC2H5)2] 35.50  Click
W 4f7/2 NiWO4 35.50  Click
W 4f7/2 [N(C4H9)4]3PMo3W9O39 35.50  Click
W 4f7/2 Al2(WO4)3 35.60  Click
W 4f7/2 Na0.1WO3 35.60  Click
W 4f7/2 Rh2WO6 35.60  Click
W 4f7/2 (Li2O)0.50(P2O5)0.05(WO3)0.45 35.60  Click
W 4f7/2 Li2WO4 35.60  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 WO3 35.70  Click
W 4f7/2 (Li2O)0.50(P2O5)0.10(WO3)0.40 35.70  Click
W 4f7/2 Na0.1WO3 35.80  Click
W 4f7/2 WO3 35.80  Click
W 4f7/2 WO3 35.80  Click
W 4f7/2 WO3 35.80  Click
W 4f7/2 WO3 35.80  Click
W 4f7/2 [NH4]10[W12O41] 35.80  Click
W 4f7/2 (N(C4H9)4)2[W6O19] 35.80  Click
W 4f7/2 [N(C4H9)4]3PMo3W9O40 35.80  Click
W 4f7/2 WBr6 35.90  Click
W 4f7/2 Li2WO4 35.90  Click
W 4f7/2 WOx/W 35.90  Click
W 4f7/2 WO3/Al2O3 35.90  Click
W 4f7/2 (Li2O)0.50(P2O5)0.15(WO3)0.35 35.90  Click
W 4f7/2 WO3/W 35.90  Click
W 4f7/2 Na2WO4 35.90  Click
W 4f7/2 WCl6 36.00  Click
W 4f7/2 Li2WO4 36.00  Click
W 4f7/2 Al2(WO4)3 36.00  Click
W 4f7/2 WO3 36.00  Click
W 4f7/2 WO3 36.00  Click
W 4f7/2 WO3 36.00  Click
W 4f7/2 WO3 36.00  Click
W 4f7/2 WO3 36.00  Click
W 4f7/2 WO3 36.00  Click
W 4f7/2 K2WO4 36.00  Click
W 4f7/2 [NH4]10[W12O41] 36.00  Click
W 4f7/2 K2WO4/Al2O3 36.00  Click
W 4f7/2 Li2W2O7 36.00  Click
W 4f7/2 (Li2O)0.50(P2O5)0.20(WO3)0.30 36.00  Click
W 4f7/2 (Li2O)0.50(P2O5)0.20(WO3)0.30 36.00  Click
W 4f7/2 (Li2O)0.50(P2O5)0.45(WO3)0.05 36.00  Click
W 4f7/2 WOx/W 36.03  Click
W 4f7/2 WCl5 36.10  Click
W 4f7/2 H2WO4 36.20  Click
W 4f7/2 [WO5((CH3)2CCH3)4] 36.20  Click
W 4f7/2 (Li2O)0.50(P2O5)0.25(WO3)0.25 36.20  Click
W 4f7/2 (Li2O)0.50(P2O5)0.30(WO3)0.20 36.20  Click
W 4f7/2 (Li2O)0.50(P2O5)0.35(WO3)0.15 36.20  Click
W 4f7/2 WBr5 36.30  Click
W 4f7/2 [NH4]6[W7O24].4H2O 36.30  Click
W 4f7/2 Al2(WO4)3 36.30  Click
W 4f7/2 Al2(WO4)3 36.30  Click
W 4f7/2 Na2WO4 36.30  Click
W 4f7/2 (Li2O)0.50(P2O5)0.40(WO3)0.10 36.30  Click
W 4f7/2 Al2(WO4)3 36.30  Click
W 4f7/2 WO3 36.40  Click
W 4f7/2 WO3 36.50  Click
W 4f7/2 WO3 36.50  Click
W 4f7/2 Al2(WO4)3 36.50  Click
W 4f7/2 WCl6 36.60  Click
W 4f7/2 WO3 36.60  Click
W 4f7/2 WO3 36.60  Click
W 4f7/2 (NH4)4[Ni(OH)6W6O18].5H2O 36.70  Click
W 4f7/2 [NH4]10[W12O41] 36.80  Click
W 4f7/2 WCl6 36.90  Click
W 4f7/2 [NH4]10[W12O41] 37.00  Click
W 4f7/2 WO2Cl2 37.10  Click
W 4f7/2 [NH4]10[W12O41] 37.10  Click
W 4f7/2 WOCl4 37.20  Click
W 4f7/2 WOCl4 37.20  Click
W 4f7/2 Na2WO4.2H2O 37.30  Click
W 4f7/2 WF6/W 37.80  Click
W 4f7/2 WF6/W 39.90  Click

 

 

Statistical Analysis of Binding Energies in NIST XPS Database of BEs

 

 

→  Periodic Table 

 

 

Advanced XPS Information Section

Expert Knowledge, Spectra, Features, Guidance and Cautions
for XPS Research Studies on Tungsten Materials

 

 

 

Expert Knowledge Examples & Explanations

→  Periodic Table 

 

Tungsten Chemical Compounds

 

Peak-fits and Overlays of Chemical State Spectra

Pure Tungsten, Wo:  W (4f)
Cu (2p3/2) BE = 932.6 eV		 WO3:  W (4f)
C (1s) BE = 285.0 eV		 Li2WO4:  W (4f)
C (1s) BE = 285.0 eV

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

Overlay of W (4f) Spectra shown Above

C (1s) BE = 285.0 eV

 

Chemical Shift between W and WO3:  4.6 eV
 Chemical Shift between W and Li2WO4:  4.4 eV

 

→  Periodic Table 

 

Tungsten Oxide (WO3)
pressed pellet

Survey Spectrum from WO3
Flood gun is ON, C (1s) BE = 285.0 eV
 W (4f) Chemical State Spectrum from WO3
Flood gun is ON, C (1s) BE = 285.0 eV
→  Periodic Table 
  
O (1s) Chemical State Spectrum from WO3
Flood gun is ON, C (1s) BE = 285.0 eV
 C (1s) Chemical State Spectrum from WO3
Flood gun is ON, C (1s) BE = 285.0 eV
→  Periodic Table 
  
Valence Band Spectrum from WO3
Flood gun is ON, C (1s) BE = 285.0 eV
  

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

 

 

Tungsten Chemical Compounds

 

Lithium Tungstate, Li2WO4

Survey W (4f)
→  Periodic Table 
C (1s) O (1s)
→  Periodic Table 
Li (1s)

→  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.

 

Quantitation from Pure, Homogeneous Binary Compound
composed of Tungsten – WO3

This section is focused on measuring and reporting the atom % quantitation that results by using:

  • Scofield cross-sections,
  • Spectra corrected to be free from Transmission Function effects
  • A Pass Energy that does not saturate the detector system in the low KE range (BE = 1000-1400 eV)
  • A focused beam of X-ray smaller than the field of view of the lens
  • An angle between the lens and the source that is ~55 deg that negates the effects of beta-asymmetry
  • TPP-2M inelastic mean free path values, and
  • Either a linear background or an iterated Shirley (Sherwood-Proctor) background to define peak areas

The results show here are examples of a method being developed that is expected to improve the “accuracy” or “reliability” of the atom % values produced by XPS.

→  Periodic Table 

 

 

Flood Gun Effect on Native Oxide of Tungsten

 

Native Oxide of Tungsten Sheet – Sample GROUNDED
versus
Native Oxide of Tungsten Sheet – Sample FLOATING

 

 

Native Oxide of Tungsten Sheet – Sample Grounded

Electron Flood Gun:  0 Voltage (FG OFF), Min Voltage versus Max Voltage

W (4f) O (1s) C (1s)
→  Periodic Table 

 

XPS Study of UHV Gas Captured by
Freshly Ion Etched Tungsten
Reveals Chemical Shifts and Chemical States that Develop from Highly Reactive Pure Wo

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.
Initial spectra are at the front.  Final spectra are at the rear. Flood gun is OFF.
W (4f) Signal
  O (1s) Signal C (1s) Signal
Copyright ©:  The XPS Library

 

AES Study of UHV Gas Captured by
Freshly Ion Etched Tungsten

Tungsten sheet was ion etched and allowed to react with residual UHV gases overnight – ~14 hr run.

W (MNN) Signal:
W at front -> WOx at rear 
W KE = 1725.6 eV,     		 O (KLL) Signal:
W at front -> WOx at rear 
O KE = 508.5 eV		 C (KLL) Signal:
W at front -> WOx at rear 
C KE = 266.0 eV
     
 

Features Observed

  • xx
  • xx
  • xx

→  Periodic Table 

 

 

Tungsten Alloys

   
XxCu XxCu
→  Periodic Table   
XxCu XxCu

 

Copyright ©:  The XPS Library 

 

 

 

XPS Facts, Guidance & Information

→  Periodic Table 

    Element Tungsten (W)
  
    Primary XPS peak used for Peak-fitting: W (4f7/2)  
    Spin-Orbit (S-O) splitting for Primary Peak: Spin-Orbit splitting for “f” orbital,  ΔBE = 2.2 eV
  
    Binding Energy (BE) of Primary XPS Signal: 31.2 eV
  
    Scofield Cross-Section (σ) Value: W (4f7/2) = 5.48     W (4f5/2) = 4.32
  
    Conductivity: W resistivity =  
Native Oxide suffers Differential Charging		  
    Range of W (4f7/2) Chemical State BEs: xx – xx eV range   (Wo to MxWO4)  
Signals from other elements that overlap
W (4f7/2) Primary Peak:		   xx (xx)
Bulk Plasmons:   ~xx eV above peak max for pure
Shake-up Peaks: xx
Multiplet Splitting Peaks:   xx

 

 

 General Information about
XXX Compounds:		   xx  
Cautions – Chemical Poison Warning

xx 

Copyright ©:  The XPS Library 

→  Periodic Table 

 

Information Useful for Peak-fitting W (4f7/2)

  • FWHM (eV) of W (4f7/2) for Pure Wo :  ~0.53 eV using 25 eV Pass Energy after ion etching
  • FWHM (eV) of W (4f7/2) for WO3:  ~1.02 eV using 50 eV Pass Energy  (before ion etching)
  • Binding Energy (BE) of Primary Signal used for Measuring Chemical State Spectra:  31.4 eV for W (4f7/2) with +/- 0.2 uncertainty
  • List of XPS Peaks that can Overlap Peak-fit results for W (4f7/2):  xxxx

→  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) = ~0.90 eV for PE 50 on Thermo K-Alpha
    • Ag (3d5/2) FWHM (eV) = ~0.95 eV for PE 80 on Kratos Nova
    • Ag (3d5/2) FWHM (eV) = ~0.95 eV for PE 45 on PHI VersaProbe
    • Ag (3d5/2) FWHM (eV) = ~0.85 eV for PE 50 on SSI S-Probe
  • 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 Oxide:  Pure element FWHM << 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 conductive compound.
  • Typical Peak-Shape:  80% G: 20% L,   or     Voigt : 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 must be constrained.

Notes:

  • Other Oxidation States can appear as small peaks when peak-fitting.
  • Pure element signals normally have asymmetric tails that should be included in the peak-fit.
  • Gaseous state materials often display asymmetric tails due to vibrational broadening.
  • Peak-fits of C (1s) in polymers include an asymmetric tail when the energy resolution is very high.
  • Binding energy shifts of a very few compounds are negative due to unusual electron polarization.

→  Periodic Table 

 

 

Contaminants Specific to Tungsten

  • Tungsten develops a thick native oxide due to the reactive nature of clean Tungsten.
  • The native oxide of WOx is 5-9 nm thick.
  • Tungsten thin films can have a low level of iron (Fe) in the bulk as a contaminant or due to sputter coater shields
  • Tungsten forms a low level of carbide when the surface is argon 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 (1s) peak max BE.
  • Low levels of carbonate is common on many s that readily oxidize in the air.
  • High levels of carbonate appear on reactive 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 (1s) 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 s.  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. The BE for C (1s) is a useful guide.  It is not absolute. Chemical shifts from native oxides can be erroneous.
  • Collect spectra from the valence band, and the principal W (4f) peak.  Auger peaks are sometimes used to decide chemical state assignments.
  • Long time exposures (high dose) to X-rays can degrade various polymers, catalysts, and 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 are sometimes used to discern chemical states when XPS shifts are very small. Auger shifts can be larger than XPS shifts.

→  Periodic Table 

 

Data Collection Settings for Tungsten (W)

  • Conductivity:  Tungsten 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:  W (4f7/2) at 31.4 eV
  • Recommended Pass Energy for Measuring Chemical State Spectrum:  40-50 eV    (Produces Ag (3d5/2) FWHM ~0.7 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:  20 – 45 eV
  • Recommended Extended BE Range for Measuring Chemical State Spectrum:  10- 100 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, As, 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

  • Carbides appear after ion etching W and various reactive surfaces.  Carbides form due to the presence of 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 

Copyright ©:  The XPS Library 
Gas Phase XPS or UPS Spectra

 

Chemical State Spectra from Literature
xx

End of File