CdI2 CsI KI LiI NaI RbI YI3 p-Iodo-Styrene    

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



Iodine (I)

 

Iodoargyrite – AgI Iodine – I flakes
(mp 114 C or 387 K) – sublimes in Vacuum
Bellingerite – Cu3(IO3)6 · 2H2O

 

  Page Index
  • Peak-fits and Overlays of F Chemical Compounds
  • Expert Knowledge & Explanations


Iodine (I)

Peak-fits, BEs, FWHMs, and Peak Labels



Lithium Iodide, LiI
I (3d) Spectrum – raw 

freshly exposed bulk
charge referenced so C (1s) = 285.0 eV

Lithium Iodide, LiI
I (3d) Spectrum – peak-fit
freshly exposed bulk
charge referenced so C (1s) = 285.0 eV



  .
Lithium Iodide, LiI
I (4d) spectrum – raw

freshly exposed bulk of a bead
Lithium Iodide, LiI
I (4d) spectrum – peak-fit

freshly exposed bulk of a bead

.
Lithium Iodide, LiI
Iodine Valence Band spectrum

freshly exposed bulk 
Lithium Iodide, LiI
Iodine Auger spectrum

freshly exposed bulk 

 


Survey Spectrum of Lithium Iodide (LiI
)
with Peaks Integrated, Assigned and Labelled


 Periodic Table 

XPS Signals for Iodine, I

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
 Na (1s) overlaps I (3s) 1071 3.53  12.0
 Cu (2p) overlaps I (3p1/2)  931 5.06  15.9
  I (3p3/2)  875  10.62 15.9
  I (3d3/2) 631.3 13.77 20.6
Cd (3p) overlaps I (3d5/2) 618.18 19.87 20.6
  I (4s) 186  0.959 28.1
Al (2s) overlaps I (4p) 122 3.34 29.2
Li (1s) overlaps I (4d) 50 4.13  

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

Energy Loss Peak:  ~  eV above peak max
Expected Bandgap for LiI:  4.2 – 4.4 eV
Expected Bandgap for LiF:  7.5 – 9 eV

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


 


Plasmon Peaks from I (3d) in KI

freshly cleaved crystal

I (3d) – Extended Range Spectrum I (3d) – Extended Range Spectrum – Vertically Zoomed

Features Observed

  • xx
  • xx
  • xx

 Periodic Table 


 

Side-by-Side Comparison of

I (3d) Spectra from:      LiI, NaI, KI, RbI, and CsI
Peak-fits, BEs, FWHMs, and Peak Labels

   
Lithium Iodide, LiI
I (3d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV
Sodium Iodide, NaI
I (3d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV
 

 


  .
Potassium Iodide, KI
I (3d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

Rubidium Iodide, RbI
I (3d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV


 
Cesium Iodide, CsI
I (3d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV

Overlay of I (3d) from
LiI, NaI, KI, RbI, and CsI


 


Survey Spectrum of Sodium Iodide, NaI
with Peaks Integrated, Assigned and Labelled

 


 


Survey Spectrum of Potassium Iodide, KI
with Peaks Integrated, Assigned and Labelled

 


 

 

Survey Spectrum of Rubidium Iodide, RbI
with Peaks Integrated, Assigned and Labelled

 


 

 

Survey Spectrum of Cesium Iodide, CsI
with Peaks Integrated, Assigned and Labelled

 

Lithium Iodide, LiI
I (4d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV
Potassium Iodide, KI
I (4d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV


  .
Sodium Iodide, NaI
I (4d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV
Rubidium Iodide, RbI
I (4d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV


  .
Cesium Iodide, CsI
I (4d) spectrum
Flood Gun ON
Charge Referenced to C (1s) at 285.0 eV
Overlay of I (4d) from
LiI, NaI, KI, RbI, and CsI
   
   

 



 

Iodine (I) in Organic Polymer

 

Peak-fits, BEs, FWHMs, and Peak Labels


para-Iodo-Styrene Polymer (-CH2-CH-C6H5I-)n

 

para-Iodo-styrene Polymer   (-CH2-CH-C6H5I-)n
I
(3d) Spectrum – raw – extended range

Freshly formed film from solution
charge referenced so C (1s) = 285.0 eV
para-Iodo-styrene Polymer   (-CH2-CH-C6H5I-)n
I (3d) Spectrum – peak-fit

Freshly formed film from solution
charge referenced so C (1s) = 285.0 eV


  .
para-Iodo-styrene Polymer   (-CH2-CH-C6H5I-)n
C (1s) Spectrum – peak-fit

Freshly formed film from solution
charge referenced so C (1s) = 285.0 eV
para-Iodo-styrene Polymer   (-CH2-CH-C6H5I-)n
C (1s) Spectrum – peak-fit – expanded

Freshly formed film from solution
charge referenced so C (1s) = 285.0 eV
 


  .
para-Iodo-styrene Polymer    (-CH2-CH-C6H5I-)n
Valence Band Spectrum 

Freshly formed film from solution
charge referenced so C (1s) = 285.0 eV
para-Iodo-styrene Polymer    (-CH2-CH-C6H5I-)n
I (KLL) Auger Spectrum 

Freshly formed film from solution
charge referenced so C (1s) = 285.0 eV
 

 

Survey Spectrum of para-Iodo-Styrene Polymer
(-CH2-CH-C6H5I-)
n
with Peaks Integrated, Assigned and Labelled


 

Copyright ©:  The XPS Library 

 Periodic Table 



 

Iodide Minerals, Crystals, and Chemical Compounds

 

Copper Iodide – CuI Radtkeite – Hg3S2ICl  Hectorfloresite – Na9(SO4)4(IO3) Dietzeite – Ca2(IO3)2(CrO4) · H2O

 



 

 

Six (6) Chemical State Tables of I (3d5/2) BEs

 

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

 



 

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 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

I (3d5/2) 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
I 53 LiI 618.2 eV   285.0 eV The XPS Library
I 53 NaI (N*2) 618.4 eV 618.7 eV 284.8 eV Avg BE – NIST
I 53 KI (N*1) 618.8 eV   284.8 eV Avg BE – NIST
I 53 LiI (N*2) 618.9 eV 619.7 eV 284.8 eV Avg BE – NIST
I 53 AgI (N*3) 619.0 eV 619.4 eV 284.8 eV Avg BE – NIST
I 53 CsI 619.1 eV   285.0 eV The XPS Library
I 53 NaI 619.2 eV   285.0 eV The XPS Library
I 53 CdI2 (N*2) 619.2 eV 619.4 eV 284.8 eV Avg BE – NIST
I 53 RbI 619.3 eV   285.0 eV The XPS Library
I 53 KI 619.7 eV   285.0 eV The XPS Library
I 53 HgI2 (N*1) 619.4 eV   284.8 eV Avg BE – NIST
I 53 PbI2 (N*1) 619.5 eV   284.8 eV Avg BE – NIST
I 53 ZnI2 (N*2) 619.7 eV 619.8 eV 284.8 eV Avg BE – NIST
I 53 I2 (N*2) 619.9 eV   284.8 eV Avg BE – NIST
I 53 I2O5 (N*1) 623.3 eV   284.8 eV Avg BE – NIST
I 53 NaIO3 (N*1) 623.5 eV   284.8 eV Avg BE – NIST
I 53 NaIO4 (N*1) 624.0 eV   284.8 eV Avg BE – NIST
I 53 I – element sublimes in vacuum   285.0 eV 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 (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

I (3d5/2) Chemical State BEs from:  “PHI Handbook”

C (1s) BE = 284.8 eV

 

 Periodic Table 

Copyright ©:  Ulvac-PHI


Table #3

I (3d5/2) Chemical State BEs from:  “Thermo-Scientific” Website

C (1s) BE = 284.8 eV

Chemical state Binding energy I (3d5/2) / eV
Metal Iodides ~619

 Periodic Table 

Copyright ©:  Thermo Scientific 


Table #4

I (3d5/2) 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

I (3d5/2) 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
I 3d5/2 Alkali iodides 618.9 ±0.8 618.1 619.7
I 3d5/2 NiI2 619.0 ±0.3 618.7 619.3
I 3d5/2 AgI 619.4 ±0.2 619.2 619.6
I 3d5/2 NiI2・6H2O 619.8 ±0.3 619.5 620.0
I 3d5/2 I2 620.0 ±0.3 619.7 620.2
I 3d5/2 ICl 621.6 ±0.3 621.3 621.8
I 3d5/2 ICl3 622.5 ±0.3 622.2 622.8
I 3d5/2 H5IO6 623.1 ±0.3 622.8 623.3
I 3d5/2 I2O5 623.3 ±0.3 623.0 623.6
I 3d5/2 NaIO3 623.5 ±0.3 623.2 623.8
I 3d5/2 NaIO4 624.0 ±0.2 623.8 624.2

 Periodic Table 


Table #6


NIST Database of I (3d5/2) 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
I 3d5/2 CsI 618.20  Click
I 3d5/2 CsI 618.20  Click
I 3d5/2 RbI 618.20  Click
I 3d5/2 NaI 618.40  Click
I 3d5/2 Cs3Sb2I9 618.50  Click
I 3d5/2 Na(N2(-CH2CH2(O)CH2CH2(O)CH2CH2-)3)I 618.60  Click
I 3d5/2 NaI 618.70  Click
I 3d5/2 KI 618.80  Click
I 3d5/2 LiI 618.90  Click
I 3d5/2 AgI 619.00  Click
I 3d5/2 CuI 619.00  Click
I 3d5/2 InI 619.00  Click
I 3d5/2 NiI2 619.00  Click
I 3d5/2 AgI 619.00  Click
I 3d5/2 CH2I2/Pd 619.00  Click
I 3d5/2 InI3 619.10  Click
I 3d5/2 CF3I 619.10  Click
I 3d5/2 [PtI2(P(C2H5)3)2] 619.20  Click
I 3d5/2 CdI2 619.20  Click
I 3d5/2 I2/Ag 619.20  Click
I 3d5/2 [NiI2(P(C6H5)3)2] 619.30  Click
I 3d5/2 (Mo6I8)I4 619.30  Click
I 3d5/2 CF3I 619.30  Click
I 3d5/2 CF3I 619.30  Click
I 3d5/2 CF3I 619.30  Click
I 3d5/2 AgI 619.40  Click
I 3d5/2 CdI2 619.40  Click
I 3d5/2 HgI2 619.40  Click
I 3d5/2 AgI 619.40  Click
I 3d5/2 I2/Ag 619.40  Click
I 3d5/2 I2/Ag 619.40  Click
I 3d5/2 CH3I/Pd 619.40  Click
I 3d5/2 CH3I/CO/Pd 619.40  Click
I 3d5/2 PbI2 619.50  Click
I 3d5/2 CH2I2/Pd 619.50  Click
I 3d5/2 [N(C3H7)4][InI4] 619.60  Click
I 3d5/2 Hg2I2 619.60  Click
I 3d5/2 SrI2 619.60  Click
I 3d5/2 CH3I/Pt 619.60  Click
I 3d5/2 [N(C2H5)4][AuI2] 619.70  Click
I 3d5/2 NiI2.6H2O 619.70  Click
I 3d5/2 [PdI2(CH3CN)2] 619.70  Click
I 3d5/2 LiI 619.70  Click
I 3d5/2 ZnI2 619.70  Click
I 3d5/2 CH2I2/Pd 619.70  Click
I 3d5/2 CH3I/Pd 619.77  Click
I 3d5/2 C6O2I4 619.80  Click
I 3d5/2 Nb6I11 619.80  Click
I 3d5/2 ZnI2 619.80  Click
I 3d5/2 [Nb6I8(CH3NH2)6] 619.90  Click
I 3d5/2 HNb6I11 619.90  Click
I 3d5/2 I2 619.90  Click
I 3d5/2 I2 619.90  Click
I 3d5/2 NbI5 619.90  Click
I 3d5/2 CH3I/Pd 619.90  Click
I 3d5/2 NbI4 620.00  Click
I 3d5/2 [AuI(P(C6H5)3)] 620.05  Click
I 3d5/2 Nb3I8 620.10  Click
I 3d5/2 CH2I2/Pd 620.10  Click
I 3d5/2 CH3I/Pd 620.10  Click
I 3d5/2 CH3I/Pd 620.27  Click
I 3d5/2 UI3 620.30  Click
I 3d5/2 CH2I2/Pd 620.40  Click
I 3d5/2 CH2I2/Pd 620.40  Click
I 3d5/2 CH3I/Pd 620.40  Click
I 3d5/2 CH3I/Pd 620.47  Click
I 3d5/2 CH2I2/Pd 620.50  Click
I 3d5/2 CH3I/Pd 620.50  Click
I 3d5/2 CH3I/Pd 620.50  Click
I 3d5/2 CH3I/Pd 620.50  Click
I 3d5/2 CH3I/CO/Pd 620.50  Click
I 3d5/2 CH3I/CO/Pd 620.50  Click
I 3d5/2 CH3I 620.55  Click
I 3d5/2 CH2I2/Pd 620.57  Click
I 3d5/2 CH2I2/Pd 620.57  Click
I 3d5/2 CH2I2/Pd 620.57  Click
I 3d5/2 CH3I/Pd 620.57  Click
I 3d5/2 (Mo6I8)I4 620.60  Click
I 3d5/2 CH3I/Pt 620.60  Click
I 3d5/2 CH2I2/Pd 620.60  Click
I 3d5/2 CH3I/Pd 620.60  Click
I 3d5/2 CH3I/Pd 620.60  Click
I 3d5/2 CH3I/Pd 620.60  Click
I 3d5/2 CH3I/Ag 620.62  Click
I 3d5/2 C2H5I/Ag 620.70  Click
I 3d5/2 CH3I/Pd 620.70  Click
I 3d5/2 CH3I/Pd 620.70  Click
I 3d5/2 Rb3Sb2I9 620.80  Click
I 3d5/2 I2 620.80  Click
I 3d5/2 CH3I 620.80  Click
I 3d5/2 C2H5I/Ag 620.80  Click
I 3d5/2 CF3I 620.90  Click
I 3d5/2 [PtI2(P(CH3)3)2] 621.10  Click
I 3d5/2 ICl3 621.50  Click
I 3d5/2 [PtI2(P(CH3)3)2] 621.90  Click
I 3d5/2 ICl3 622.50  Click
I 3d5/2 H5IO6 623.00  Click
I 3d5/2 HIO3 623.10  Click
I 3d5/2 I2O5 623.30  Click
I 3d5/2 NaIO3 623.50  Click
I 3d5/2 NaIO4 624.00  Click
I 3d5/2 Na(NiIO6).H2O 624.40  Click
 

 Periodic Table 


 

 

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 Iodine Materials

 


 

Expert Knowledge Explanations

 


 

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 KI

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.

Copyright ©:  The XPS Library 

 



 

XPS Facts, Guidance & Information

 Periodic Table 

    Element   Iodine (I)
 
    Primary XPS peak used for Peak-fitting :   I (3d5/2)  
    Spin-Orbit (S-O) splitting for Primary Peak:   Spin-Orbit splitting for Iodine “d” orbital:  11.6 eV
 
    Binding Energy (BE) of Primary XPS Signal:   618 eV
 
    Scofield Cross-Section (σ) Value:   I (3d5/2) = 19.87     I (3d3/2) = 13.77
 
    Conductivity:      
    Range of I (3d5/2) Chemical State BEs:   618 – 623 eV range   (I- to -CIx)  
    Signals from other elements that overlap
I (3d5/2) Primary Peak:
     
    Bulk Plasmons:   ~xxx eV above peak max for pure  
    Shake-up Peaks:   ??  
    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 I (3d5/2)

  • FWHM (eV) of Metal I- :  ~1.2 eV using 50 eV Pass Energy after ion etching:
  • FWHM (eV) of IOx xtal:  ~1.6 eV using 50 eV Pass Energy  (before ion etching)
  • Binding Energy (BE) of Primary Signal used for Measuring Chemical State Spectra:  4684-692 eV for I (3d5) with +/- 0.2 uncertainty
  • List of XPS Peaks that can Overlap Peak-fit results for I (3d):  xx

 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 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 or 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 some compounds are negative due to unusual electron polarization.

 Periodic Table 


 

Contaminants Specific to Iodides

  • METAL Iodide thin films often have a low level of iron (Fe) in the bulk as a contaminant or to strengthen the thin film
  • METAL Iodide degrades slightly 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 (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
  • Collect principal I (3d) peak as well as I (4d).
  • 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 Metal Iodide (I)

  • Conductivity:  Metal Iodides do not readily develops a native oxide that is sensitive to Flood Gun.
  • Primary Peak (XPS Signal) used to measure Chemical State Spectra:  I (3d5/2) at 619 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:  610 – 640 eV
  • Recommended Extended BE Range for Measuring Chemical State Spectrum:  600 – 700 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

  • Carbides appear after ion etching metals and various reactive surfaces.  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 

Copyright ©:  The XPS Library 


 
 
Gas Phase XPS or UPS Spectra
 

 
     
     
     
     
     
     
     
     
     
 
 
 
 

 

Chemical State Spectra from Literature
 



End of File