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.
 Periodic Table – HomePage                         XPS Database of Polymers                     → Six (6) BE Tables


 

Gold (Au)
Aurum

Krennerite – Au3AgTe8 Gold – Auo Calverite – AuTe2

 

  Page Index
  • Expert Examples & Explanations


Gold (Auo) Metal
Peak-fits, BEs, FWHMs, and Peak Labels


  .
Gold (Auo) Metal
Au (4f) Spectrum – raw spectrum

ion etched clean
Gold (Auo) Metal
Peak-fit of Au (4f) Spectrum
w/o asymm


 Periodic Table – HomePage  
Gold (Auo) Metal
Au (4f) Spectrum –
extended range 
Gold (Auo) Metal
Peak-fit of Au (4f) Spectrum (w asymm)

 

 

Survey Spectrum of Gold (Auo)
with Peaks Integrated, Assigned and Labelled

 


 Periodic Table 

XPS Signals for Gold (Auo) 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
  Au (4s) 751 1.92 9.8
Mn (2p) overlaps Au (4p1/2) 642 2.14 11.8
  Au (4p3/2) 546 5.89 11.8
  Au (4d3/2) 353 8.06 13.7
Ca (2p) overlaps Au (4d5/2) 335 11.74 13.7
  Au (4f5/2) 87.63 7.54 15.8
  Au (4f7/2) 83.96 9.58 15.8
Si (2p) overlaps Au (5s) 109 0.479 15.6
Al (2p) & Cu (3p) overlap Au (5p1/2) 73.5 0.463 16.0
Li (1s) overlaps Au (5p3/2) 57.5 1.10 16.0
  Au (5d)  3.5 1.808 xx.x

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

Energy Loss    Intrinsic Plasmon Peak:  ~xx eV above peak max
Expected Bandgap for Au2O3: 0.8 – 0.9 eV
Work Function for Au:  xx eV

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

 Periodic Table 


 

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

 


 

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

Au (4f) – Extended Range Spectrum Au (4f) – Extended Range Spectrum – Vertically Zoomed
 Periodic Table 

 

Au (MNN) Auger Peaks from Auo Metal
 Fresh exposed bulk produced by extensive Ar+ ion etching

Auo Metal – main Auger peak Auo Metal – full Auger range
   

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

Artefacts Caused by Argon Ion Etching

C (1s) from Gold Carbide(s)

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

Argon Trapped in Auo

can form when Argon Ions are used
to removed surface contamination

na na

 

Side-by-Side Comparison of

Auo metal (native oxide) & Gold Oxide, Au2O3 (Au 86%)
Peak-fits, BEs, FWHMs, and Peak Labels

Auo metal (native oxide ?) Au2O3
Au (4f) from Au metal
Flood Gun OFF
As-Measured, C (1s) at 285.4 eV 
Au (4f) from Au2O3 – pellet
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV


 Periodic Table 
 
Au metal (native oxide?) Au2O3
C (1s) from Au metal
Flood Gun OFF
As-Measured, C (1s) at 285.4 eV

C (1s) from Au2O3– pellet
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 


 Periodic Table 
 
Au metal (native oxide?) Au2O3
O (1s) from Au metal
Flood Gun OFF
As-Measured, C (1s) at 285.4 eV

O (1s) from Au2O3 – pellet
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 


 Periodic Table 
Au metal (native oxide?) Au2O3
Au Valence Band Au metal
Flood Gun OFF
As-Measured, C (1s) at 285.4 eV

Au Valence Band Au2O3
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

 

 


 


Survey Spectrum of Au metal  (native oxide?)

with Peaks Integrated, Assigned and Labelled

 

 Periodic Table 


 

 

Survey Spectrum of Gold Oxide (Au2O3)
with Peaks Integrated, Assigned and Labelled

 Periodic Table  


 

Overlays of Au (4f) Spectra for:
Auo metal, Native Oxide (?) and Au2O3

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

 Overlay of Auo  (native oxide?) and Au2O3 – Au (4f)
Native Oxide C (1s) = 285.4 eV  (Flood gun OFF)
 Overlay of Auo metal and Au2O3 – Au (4f)
Native Oxide C (1s) = 285.0 eV  (Flood gun ON)

 Periodic Table  Copyright ©:  The XPS Library 

 

Overlay of Au (4f)
Auo metal & Au (native oxide) 

 

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

Valence Band Spectra
Auo, Au2O3 

Auo
Ion etched clean
Au2O3 – pellet
Flood gun is ON,  Charge referenced so C (1s) = 285.0 eV


Overlay of Valence Band Spectra
for Auo metal and Au2O3 



Overlay of Valence Band Spectra

for Auo metal and Au (native oxide?)

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 



 

Gold Minerals, Gemstones, and Chemical Compounds

 

Gold Oxide – Au2O3 Gold Hydroxide – Au(OH)3 Gold Bromide – AuBr3 Gold Single Crystal – Au <111>
on Sapphire

 Periodic Table 



 

 

Six (6) Chemical State Tables of Au (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

Au (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
Au 79 Au (N*26) 83.7 eV 84.2 eV 284.8 eV Avg BE – NIST
Au 79 Au – element 83.9 eV   285.0 eV The XPS Library
Au 79 AuSi (N*3) 83.9 eV 84.5 eV 284.8 eV Avg BE – NIST
Au 79 Au-Te2 (N*1) 84 eV   284.8 eV Avg BE – NIST
Au 79 Au-Cu (75:25) 84.11 eV   285.0 eV The XPS Library
Au 79 Au-Cu (50:50) 84.25 eV   285.0 eV The XPS Library
Au 79 Au-Cu (25:75) 84.42 eV   285.0 eV The XPS Library
Au 79 Au-I (N*1) 84.5 eV   284.8 eV Avg BE – NIST
Au 79 Au-Cl (N*1) 84.6 eV   284.8 eV Avg BE – NIST
Au 79 Au-In (N*2) 84.6 eV 84.9 eV 284.8 eV Avg BE – NIST
Au 79 AuInOx (N*3) 84.8 eV 85.8 eV 284.8 eV Avg BE – NIST
Au 79 Au-2O3 85.1 eV   285.0 eV The XPS Library
Au 79 Au-Ga (N*2) 85.3 eV 85.6 eV 284.8 eV Avg BE – NIST
Au 79 Au2O3 (N*1) 85.9 eV   284.8 eV Avg BE – NIST
Au 79 Au-(OH)3     285.0 eV The XPS Library

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

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

C (1s) BE = 284.8 eV

 Periodic Table 

Copyright ©:  Ulvac-PHI


Table #3

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

C (1s) BE = 284.8 eV

Chemical state Binding energy (eV), Au (4f7/2)
Au metal 84.0 eV

 Periodic Table 

Copyright ©:  Thermo Scientific 


Table #4

Au (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

Au (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
Au 4f7/2 Au 84.0 ±0.2 83.8 84.2
Au 4f7/2 (-AuCH2PEt2CH2-)2 84.1 ±0.3 83.8 84.3
Au 4f7/2 AuSn 84.5 ±0.3 84.2 84.8
Au 4f7/2 YbAu2 84.6 ±0.3 84.3 84.8
Au 4f7/2 (-AuSPEt2S-)2 84.9 ±0.3 84.6 85.1
Au 4f7/2 AuSn4 85.1 ±0.3 84.8 85.3
Au 4f7/2 ClAu(Ph3As) 85.2 ±0.3 84.9 85.4
Au 4f7/2 ClAu(Ph3P)2 85.5 ±0.3 85.2 85.7
Au 4f7/2 (Ph3P)AuNo3 85.5 ±0.3 85.2 85.7
Au 4f7/2 ClAuPh3P 85.5 ±0.2 85.3 85.7
Au 4f7/2 Cl3AuPh3P 87.3 ±0.3 87.0 87.5

 

 Periodic Table 



 


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

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

 

Histogram indicates:  83.98 eV for Auo based on 27 literature BEs  

 

 

Table #6


NIST Database of Au (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
Au 4f7/2 AgAuTe4 83.20  Click
Au 4f7/2 Au 83.70  Click
Au 4f7/2 Au 83.70  Click
Au 4f7/2 AuV3 (A15II) 83.70  Click
Au 4f7/2 Au 83.74  Click
Au 4f7/2 Au 83.80  Click
Au 4f7/2 Au 83.80  Click
Au 4f7/2 Au 83.81  Click
Au 4f7/2 Au 83.83  Click
Au 4f7/2 Au55(P(C6H4OCH3)3)12Cl6 83.84  Click
Au 4f7/2 Au 83.86  Click
Au 4f7/2 Au/Ru 83.87  Click
Au 4f7/2 Au/Ru 83.88  Click
Au 4f7/2 Au/Ru 83.88  Click
Au 4f7/2 Au/Ru 83.89  Click
Au 4f7/2 AuV3 (A15I) 83.90  Click
Au 4f7/2 Au81Si19 83.90  Click
Au 4f7/2 Ag/Au/Ru 83.93  Click
Au 4f7/2 Ag/Au/Ru 83.93  Click
Au 4f7/2 Au 83.95  Click
Au 4f7/2 Au/GaAs 83.95  Click
Au 4f7/2 Au/Ru 83.95  Click
Au 4f7/2 Au 83.97  Click
Au 4f7/2 Au 83.97  Click
Au 4f7/2 Au/Ag/Ru 83.97  Click
Au 4f7/2 Au 83.98  Click
Au 4f7/2 Au 83.98  Click
Au 4f7/2 Au 83.98  Click
Au 4f7/2 Au/Ag/Ru 83.99  Click
Au 4f7/2 [Au2(P(C2H5)2)2((CH2)2)2] 84.00  Click
Au 4f7/2 Au 84.00  Click
Au 4f7/2 Au 84.00  Click
Au 4f7/2 Au 84.00  Click
Au 4f7/2 Au 84.00  Click
Au 4f7/2 Au 84.00  Click
Au 4f7/2 Au 84.00  Click
Au 4f7/2 Au59Si41 84.00  Click
Au 4f7/2 AuTe2 84.00  Click
Au 4f7/2 (C100H158N2O4)n/Au 84.00  Click
Au 4f7/2 C82H114Br2N2O4/Au 84.00  Click
Au 4f7/2 K(CH3CH2OCS2)/Au 84.00  Click
Au 4f7/2 K(CH3CH2OCS2)/Au 84.00  Click
Au 4f7/2 CH3(CH2)19CN 84.00  Click
Au 4f7/2 NCCH2CN/Au 84.00  Click
Au 4f7/2 (C112H166N2O4)n/Au 84.00  Click
Au 4f7/2 Au/Pd 84.00  Click
Au 4f7/2 Au/Pd 84.00  Click
Au 4f7/2 Ag28.6Au17.1Cu54.3 84.00  Click
Au 4f7/2 Au/Cu/Ru 84.01  Click
Au 4f7/2 Au 84.04  Click
Au 4f7/2 Au81Si19 84.05  Click
Au 4f7/2 Cu/Au/Ru 84.05  Click
Au 4f7/2 Au/Cu/Ru 84.05  Click
Au 4f7/2 Au/Ag/Ru 84.06  Click
Au 4f7/2 Au3Cu 84.06  Click
Au 4f7/2 Au3Cu 84.06  Click
Au 4f7/2 Cu/Au/Ru 84.06  Click
Au 4f7/2 Au/Cu/Ru 84.06  Click
Au 4f7/2 Au 84.07  Click
Au 4f7/2 Cu/Au/Ru 84.07  Click
Au 4f7/2 Cu/Au/Ru 84.07  Click
Au 4f7/2 Au/Cu/Ru 84.09  Click
Au 4f7/2 Au 84.10  Click
Au 4f7/2 Au/Cu/Ru 84.10  Click
Au 4f7/2 Au 84.15  Click
Au 4f7/2 [Au(CH2)2P(C6H5)2]2 84.15  Click
Au 4f7/2 Au90Sn10 84.16  Click
Au 4f7/2 Cu/Au/Ru 84.17  Click
Au 4f7/2 [N(C2H5)4][AuI2] 84.20  Click
Au 4f7/2 Au 84.20  Click
Au 4f7/2 [(C4H9)4N][AuCl2] 84.20  Click
Au 4f7/2 Au 84.21  Click
Au 4f7/2 Au 84.22  Click
Au 4f7/2 Au86Sn14 84.22  Click
Au 4f7/2 Au/Cu/Ru 84.24  Click
Au 4f7/2 Au 84.25  Click
Au 4f7/2 [Au(CH2)2P(C6H5)2]2Br2 84.25  Click
Au 4f7/2 AuCu 84.25  Click
Au 4f7/2 AuCu3 84.26  Click
Au 4f7/2 AuIn0.111 84.27  Click
Au 4f7/2 AuIn0.111 84.27  Click
Au 4f7/2 [N(C2H5)4][AuI2]I2 84.30  Click
Au 4f7/2 K2[Au(SCN)4] 84.30  Click
Au 4f7/2 AuV3 (A2) 84.30  Click
Au 4f7/2 Cu3Au 84.30  Click
Au 4f7/2 Au34Si66 84.30  Click
Au 4f7/2 Cu/Au/Ru 84.30  Click
Au 4f7/2 AuCu 84.31  Click
Au 4f7/2 Au70.5Sn29.5 84.32  Click
Au 4f7/2 [Au(CH2)2P(C6H5)2]2 84.35  Click
Au 4f7/2 AuCu3 84.37  Click
Au 4f7/2 [CNPt(AuP(C6H5)3)8AuCN]NO3 84.37  Click
Au 4f7/2 [P(C6H5)3COPt(AuP(C6H5)3)5]Cl 84.37  Click
Au 4f7/2 [N(C2H5)4][AuBr2] 84.40  Click
Au 4f7/2 [AuCl((CH3)2S(O)CH2)2] 84.40  Click
Au 4f7/2 (N(C6H5)-C(CH3)=C(CN)-C(S)-S-CH2-C(O)-O-C2H5)AuCl 84.40  Click
Au 4f7/2 Cu3Au 84.40  Click
Au 4f7/2 Cs2Au2Br6 84.40  Click
Au 4f7/2 Cs2Au2I6 84.40  Click
Au 4f7/2 AuI 84.40  Click
Au 4f7/2 [(C4H9)4N][AuBr2] 84.40  Click
Au 4f7/2 [(C4H9)4N][AuI4] 84.40  Click
Au 4f7/2 [Pt(AuP(C6H5)3)8](NO3)2 84.40  Click
Au 4f7/2 [CN(CH3)2C6H3Pt(AuP(C6H5)3)8](NO3)2 84.43  Click
Au 4f7/2 AuCu7 84.43  Click
Au 4f7/2 Au88Ga12 84.44  Click
Au 4f7/2 Au/InP 84.45  Click
Au 4f7/2 [Au8(P(C6H5)3)8](NO3)2 84.47  Click
Au 4f7/2 AuCu19 84.47  Click
Au 4f7/2 [AuHSCH2C(NH2)HCO2H] 84.50  Click
Au 4f7/2 [Au11I3(P(C6H5)3)7] 84.50  Click
Au 4f7/2 [Au11I3(P(C6H5)3)7] 84.50  Click
Au 4f7/2 [Au8(CH3C5H4N)2(P(C6H5)3)8] 84.50  Click
Au 4f7/2 [Au4I2(P(C6H5)3)4] 84.50  Click
Au 4f7/2 [Au4I2(P(C6H5)3)4] 84.50  Click
Au 4f7/2 Au45Si55 84.50  Click
Au 4f7/2 Cs2Au2Cl6 84.50  Click
Au 4f7/2 [(C4H9)4N][AuI2] 84.50  Click
Au 4f7/2 [P(C6H5)3CNPt(AuP(C6H5)3)6]NO3 84.50  Click
Au 4f7/2 Au81Si19 84.53  Click
Au 4f7/2 [P(C6H5)3Pt(AuP(C6H5)3)6(HgNO3)]NO3 84.57  Click
Au 4f7/2 [IP(C6H5)3Pt(AuP(C6H5)3)4]BF4 84.57  Click
Au 4f7/2 Au3In 84.58  Click
Au 4f7/2 Au3In 84.58  Click
Au 4f7/2 [Au11Cl(P(C6H5)3)9]Cl2 84.60  Click
Au 4f7/2 Cs2Au2I6 84.60  Click
Au 4f7/2 AuIn1.6O0.8 84.60  Click
Au 4f7/2 AuCl 84.60  Click
Au 4f7/2 Au46Zn54 84.64  Click
Au 4f7/2 Au78Ga22 84.64  Click
Au 4f7/2 AuIn1.3O0.9 84.65  Click
Au 4f7/2 [P(C6H5)3Pt(AuP(C6H5)3)5(HgNO3)2]NO3 84.65  Click
Au 4f7/2 [P(C6H5)3Pt(AuP(C6H5)3)6](NO3)2 84.68  Click
Au 4f7/2 [(P(C6H5)3)2Pt(AuP(C6H5)3)3]PF6 84.68  Click
Au 4f7/2 [Au8(P(C6H5)3)8](ClO4)2 84.70  Click
Au 4f7/2 [Au8(P(C6H5)3)8](+2) 84.70  Click
Au 4f7/2 [Au11(P(CH3OC6H4)3)10](+3) 84.70  Click
Au 4f7/2 [AuCl(CH2P(C6H5)3)2] 84.70  Click
Au 4f7/2 [(C6H5)3PCH2]2AuCl 84.70  Click
Au 4f7/2 [(C6H5)3PCH2]2AuCl 84.70  Click
Au 4f7/2 [P(C6H5)3HPt(AuP(C6H5)3)7](NO3)2 84.72  Click
Au 4f7/2 Au55Mg45 84.74  Click
Au 4f7/2 AuInOx 84.75  Click
Au 4f7/2 AuInOx 84.75  Click
Au 4f7/2 [(CO)3(P(C6H5)3)4Pt3(AuP(C6H5)3)]NO3 84.77  Click
Au 4f7/2 [AuSP(C2H5)2S]2 84.80  Click
Au 4f7/2 [Au(C(O)OCH(NH2)C(CH3)2SH)].nH2O 84.80  Click
Au 4f7/2 [(C6H5)3PCH2]-[(C6H5)3P]AuCl 84.80  Click
Au 4f7/2 [(Pt(P(C6H5)3)2S)2Au(P(C6H5)3)]PF6 84.80  Click
Au 4f7/2 AuIn 84.85  Click
Au 4f7/2 AuIn 84.85  Click
Au 4f7/2 [(C6H5)2PCH2CH2P(C6H5)2Pt(AuP(C6H5)3)4](PF6)2 84.87  Click
Au 4f7/2 Au70.5Sn29.5 84.87  Click
Au 4f7/2 [AuHS(CH2)8SH] 84.90  Click
Au 4f7/2 Na[Au(OOCCH2CH(SH)COO)] 84.90  Click
Au 4f7/2 [AuPt3(CO)3(C6H11PH2)4].PF6 84.90  Click
Au 4f7/2 Au9Ga4 84.91  Click
Au 4f7/2 Au50Sn50 84.91  Click
Au 4f7/2 [Au(P(C6H5)3)4]ClO4 85.00  Click
Au 4f7/2 [Au9(NO3)3(P(C6H5)3)8] 85.00  Click
Au 4f7/2 [Au9(CH3C5H4N)3(P(C6H5)3)8] 85.00  Click
Au 4f7/2 [Au9(P(C6H5)8)](+3) 85.00  Click
Au 4f7/2 [Au11(P(CH3C6H5O)3)10](+3) 85.00  Click
Au 4f7/2 [Au9(P(CH3C6H4O)3)8](+3) 85.00  Click
Au 4f7/2 [(C6H5)3P]2AuCl 85.00  Click
Au 4f7/2 [Au11(SCN)3(P(C6H5)3)7] 85.05  Click
Au 4f7/2 [N(C2H5)4][AuCl2] 85.10  Click
Au 4f7/2 Au(P(C6H5)3)NO3 85.17  Click
Au 4f7/2 [AuCl(P(C6H5)3)2] 85.20  Click
Au 4f7/2 [AuCl(As(C6H5)3)] 85.20  Click
Au 4f7/2 [Au9(NO3)3(P(C6H5)3)8] 85.20  Click
Au 4f7/2 [AuCl(P(C2H5)3)] 85.20  Click
Au 4f7/2 AuIn2 85.20  Click
Au 4f7/2 AuIn2 85.20  Click
Au 4f7/2 Au50Ga50 85.29  Click
Au 4f7/2 [AuCl(P(C6H5)3)] 85.30  Click
Au 4f7/2 [AuCl(P(C6H5)3)] 85.30  Click
Au 4f7/2 Cs2Au2I6 85.30  Click
Au 4f7/2 Au50Cs50/Ru 85.30  Click
Au 4f7/2 Au(P(C6H5)3)Cl 85.35  Click
Au 4f7/2 [AuCl(P(C6H5)3)2] 85.40  Click
Au 4f7/2 [AuNO3(P(C6H5)3)] 85.40  Click
Au 4f7/2 [AuI(P(C6H5)3)] 85.40  Click
Au 4f7/2 [AuI(P(C6H5)3)] 85.40  Click
Au 4f7/2 [AuI(P(C6H5)3)] 85.40  Click
Au 4f7/2 [Au9(NO3)3(P(C6H5)3)8] 85.45  Click
Au 4f7/2 [AuCl(P(C6H5)3)] 85.50  Click
Au 4f7/2 AuGa2 85.56  Click
Au 4f7/2 [Au(SCN)4(P(C6H5)4)2] 85.60  Click
Au 4f7/2 Cs2Au2Br6 85.60  Click
Au 4f7/2 AuInOx 85.80  Click
Au 4f7/2 Au2O3 85.90  Click
Au 4f7/2 [Au(CH2)2P(C6H5)2]2Br2 86.30  Click
Au 4f7/2 CsAu0.6Br2.6 86.30  Click
Au 4f7/2 Cs2Au2Cl6 86.30  Click
Au 4f7/2 [AuBr(P(C6H5)3)] 86.35  Click
Au 4f7/2 [AuCl(P(C6H5)3)] 86.45  Click
Au 4f7/2 [Au(CH2)2P(C6H5)2]2Br2 86.50  Click
Au 4f7/2 [Au9(P(C6H5)3)8](ClO4)3 86.55  Click
Au 4f7/2 [AuNO3(P(C6H5)3)] 86.55  Click
Au 4f7/2 [Au(P(C6H5)3)2]B(C6H5)4 86.55  Click
Au 4f7/2 [Au(CH2)2P(C6H5)2]2Br4 86.60  Click
Au 4f7/2 [Au(CH2)2P(C6H5)2]2Br4 86.60  Click
Au 4f7/2 [AuI(P(C6H5)3)] 86.65  Click
Au 4f7/2 [N(C2H5)4][AuBr2]Br2 86.70  Click
Au 4f7/2 [(C4H9)4N][AuBr4] 86.70  Click
Au 4f7/2 [Au9(P(C6H5)3)8](PF6)3 86.75  Click
Au 4f7/2 Cs[AuBr4] 86.80  Click
Au 4f7/2 [Au8(P(C6H5)3)8](PF6)2 86.85  Click
Au 4f7/2 [Au(P(C6H5)3)2]NO3 86.85  Click
Au 4f7/2 [(C4H9)4N][AuCl4] 86.90  Click
Au 4f7/2 [Au(C(O)OCH(NH2)C(CH3)2(SH))2] 87.00  Click
Au 4f7/2 [AuBr3P(C2H5)3] 87.10  Click
Au 4f7/2 [AuCl3(P(C6H5)3)] 87.30  Click
Au 4f7/2 [AuI3(P(C6H5)3)] 87.40  Click
Au 4f7/2 [Au(P(C6H5)3)3]I3 87.40  Click
Au 4f7/2 [AuCl3(P(C6H5)3)] 87.50  Click
Au 4f7/2 Cs[AuCl4] 87.50  Click
Au 4f7/2 [AuCl3P(C2H5)3] 87.70  Click
Au 4f7/2 CH3(CH2)19CN 87.70  Click
Au 4f7/2 Ag28.6Au17.1Cu54.3 87.70  Click
Au 4f7/2 [N(C2H5)4][AuCl2]Cl2 87.80  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 Gold Materials

 


 

Expert Knowledge Examples & Explanations

 Periodic Table 


 


Gold Chemical Compounds


Peak-fits and Overlays of Chemical State Spectra

Pure Gold:  Au (4f)
Cu (2p3/2) BE = 932.6 eV
Au2O3:  Au (4f)
C (1s) BE = 285.0 eV
 
 

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

Overlay of Au (4f) Spectra shown Above

C (1s) BE = 285.0 eV

 

Chemical Shift between Au and Au2O3:  3.0 eV

 

 Periodic Table 


 

Gold Oxide (Au2O3)
pressed pellet

Survey Spectrum from Au2O3
Flood gun is ON, C (1s) BE = 285.0 eV
Au (4f) Chemical State Spectrum from Au2O3
Flood gun is ON, C (1s) BE = 285.0 eV

 
O (1s) Chemical State Spectrum from Au2O3
Flood gun is ON, C (1s) BE = 285.0 eV
C (1s) Chemical State Spectrum from Au2O3
Flood gun is ON, C (1s) BE = 285.0 eV

 
Valence Band Spectrum from Au2O3
Flood gun is ON, C (1s) BE = 285.0 eV

Auger Signals from Au2O3
Flood gun is ON, C (1s) BE = 285.0 eV

na


Shake-up Features for Au2O3

na  
   

 


 

Multiplet Splitting Features for Gold Compounds

Au metal – NO Splitting for Au (4s) Au2O3 – Splitting Peaks for Au (4s)
NA NA

 

 

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 

 


 

Gold Alloys

 

Au:Cu Alloys
full plots are displayed later

Au (4f)
from Au:Cu Alloy Series
(shown at end)
Cu (2p3/2)
from Au:Cu Allow Series
(shown at end)
   
   

 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 Gold – Au2O3

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 Gold

 

Native Oxide of Gold Sheet – Sample GROUNDED

 


 

Native Oxide of Gold Sheet – Sample Grounded

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

Au (4f)
Flood Gun Induced Shift: 0.07 eV
O (1s)
Flood Gun Induced Shift:  0.12 eV
C (1s)
Flood Gun Induced Shift:  0.26 eV
     
 Periodic Table     

 

 

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

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.
 
 
 
Au (4f) Signal
Reverse View
 O (1s) Signal C (1s) Signal
     
 
 
Copyright ©:  The XPS Library
 

 


AES Study of UHV Gas Captured by Freshly Ion Etched Gold

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

Au (MNN) Signal:
Au at front -> AuOx at rear 
Au KE = XXXX eV,    AuO KE = XXXX eV
O (KLL) Signal:
Au at front -> AuOx at rear 
O KE = XXXX eV
C (KLL) Signal:
Au at front -> AuOx at rear 
O KE = XXXX eV
   
     
Au (KLL) 
   

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

 

Gold Alloys

Au:Cu ratios =   75:25,  50:50,  25:75

 

Au:Cu 75:25
Survey Spectrum
Au:Cu 75:25
Au (4f7/2) BE = 84.11 eV
Au:Cu 75:25
Cu (2p3/2) BE = 932.41 eV

   
Au:Cu 50:50
Survey Spectrum
Au:Cu 50:50
Au (4f7/2) BE = 84.25 eV
Au:Cu 50:50
Cu (2p3/2) BE = 932.55 eV

 Periodic Table     
Au:Cu 25:75
Survey Spectrum
Au:Cu 25:75
Au (4f7/2) BE = 84.42 eV
Au:Cu 25:75
Cu (2p3/2) BE = 932.65 eV

 


Effect of Bond Polarization 

Due to Alloying Gold and Copper Metals
 

 Overlay of Au (4f) from the 3 AuCu Alloys  Overlay of Cu (2p3/2) from the 3 AuCu Alloys
Au (4f7/2) BEs:  84.11, 84.25 and 84.42 eV Cu (2p3/2):  932.41, 932.55 and 932.65 eV
Difference in Minimum and Maximum BEs for Au (4f7/2):   0.31 eV Difference in Minimum and Maximum BEs for Cu (2p3/2):  0.24 eV
   

Copyright ©:  The XPS Library 

 



 


XPS Facts, Guidance & Information

 Periodic Table 

    Element   Gold (Au)
 
    Primary XPS peak used for Peak-fitting:   Au (4f7/2)  
    Spin-Orbit (S-O) splitting for Primary Peak:   Spin-Orbit splitting for “f” orbital,  ΔBE = 3.67 eV
 
    Binding Energy (BE) of Primary XPS Signal:   83.96 eV
 
    Scofield Cross-Section (σ) Value:   Au (4f7/2) = 9.58    Au (4f5/2) = 7.54
 
    Conductivity:   Au resistivity =  
Native Oxide suffers Differential Charing
 
    Range of Au (4f7/2) Chemical State BEs:   84  – 87 eV range   (Auo to AuF3)  
    Signals from other elements that overlap
Au (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 Au (4f7/2)

  • FWHM (eV) of Au (4f7/2) for Pure Auo ~0.7 eV using 25 eV Pass Energy after ion etching
  • FWHM (eV) of Au (4f7/2) for Au2O3 ~1.37 eV using 50 eV Pass Energy  (before ion etching)
  • Binding Energy (BE) of Primary Signal used for Measuring Chemical State Spectra:  83.96 eV for Au (4f7/2) with +/- 0.1 uncertainty
  • Typical Peak-Shape:  70% G: 30% L,   or     Voigt : 1.4 eV Gaussian and 0.5 eV Lorentzian
  • Asymmetry for Conductive materials:  20-30% with increased Lorentzian %
  • List of XPS Peaks that can Overlap Peak-fit results for Au (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.
  • Constraints used on Peak-fitting: typically constrain the peak area ratios based on the Scofield cross-section values
  • Asymmetry for Conductive materials:  20-30% with increased Lorentzian %
  • Peak-fitting “2s” or “3s” Peaks:  Often need to use 50-60% Lorentzian peak-shape

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 Gold

  • Gold develops a thick native oxide due to the reactive nature of clean Gold.
  • The native oxide of AuOx is 0-1 nm thick for very old metal surfaces.
  • Gold thin films can have a low level of iron (Fe) in the bulk as a contaminant or due to sputter coater shields
  • Gold 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 Au (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 Gold (Au)

  • Conductivity:  Gold 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:  Au (4f7/2) at 84 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:  75- 95eV
  • Recommended Extended BE Range for Measuring Chemical State Spectrum:  70- 170 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 Au 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
 
 
AuCu
 



End of File