Beo | BeO | native BeOx | Be(SO4) | Be2SiO4 | BeAl2O4 | BeF2 | BeN | BeC | CuBe |
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 XPS Database of Polymers →Six (6) BE Tables
Beryllium (Be)
Beryl – Be3Al2Si6O18 | Beryllium Metal – Beo | Beryllonite – BePO4 |
Page Index | |||
|
- Expert Knowledge Explanations
Peak-fits, BEs, FWHMs, and Peak Labels
Beryllium, (Beo) Metal Be (1s) Spectrum – raw |
Beryllium, (Beo) Metal Peak-fit of Be (1s) Spectrum |
||||||||||||||||||
Survey Spectrum of Beryllium (Beo) |
|||||||||||||||||||
→ Periodic Table | |||||||||||||||||||
|
|||||||||||||||||||
XPS Signals for Pure Beryllium (Beo) Metal Spin-Orbit Term, BE (eV) Value, and Scofield σ for Aluminum Kα X-rays (1486 eV, 8.33 Ang)
σ: abbreviation for the term Scofield Photoionization Cross-Section which are used with IMFP and TF to generate RSFs and atom% quantitation Intrinsic Plasmon Peak: ~20 eV above peak max *Scofield Cross-Section (σ) for C (1s) = 1.0
Valence Band Spectrum from Beo Metal Fresh exposed bulk produced by extensive Ar+ ion etching
Plasmon Peaks from Beo Metal
Be (KLL) Auger Peaks from Beo Metal
Artefacts Caused by Argon Ion Etching
Side-by-Side Comparison of |
|||||||||||||||||||
Be Native Oxide | Beryllium Oxide, BeO | ||||||||||||||||||
Be (1s) from Native Oxide on Beo metal Flood Gun OFF As-measured, C (1s) at 286.3 eV |
Be (1s) from BeO pressed pellet Flood Gun ON Charge Referenced to C (1s) at 285.0 eV |
||||||||||||||||||
|
|||||||||||||||||||
|
|||||||||||||||||||
C (1s) from Native Oxide on Beo metal |
C (1s) from BeO pressed pellet |
||||||||||||||||||
|
|||||||||||||||||||
|
|||||||||||||||||||
O (1s) from Native Oxide on Beo metal |
O (1s) from BeO pressed pellet |
||||||||||||||||||
|
Copyright ©: The XPS Library
Overlays of Spectra
from Beo metal, Native Beryllium Oxide and BeO
Caution: BEs from Grounded Native Oxides can be Misleading when Flood Gun is ON
Be (1s) Overlay of Pure Beo Metal and Be Native Oxide Native Oxide C (1s) = 286.3 eV (FG Off) Chemical Shift: 2.9 |
Be (1s) Overlay of Pure Beo Metal and Pure BeO Pure Oxide C (1s) = 285.0 eV Chemical Shift: 1.7 |
Overlay of Be (1s)
Pure Beo Metal, Be Native Oxide & Pure BeO
Features Observed
- xx
- xx
- xx
Beo | BeO |
|
|
Survey Spectrum of Beryllium Oxide (BeO)
with Peaks Integrated, Assigned and Labelled
Survey Spectrum of Beryllium (Be) Native Oxide
with Peaks Integrated, Assigned and Labelled
Beryllium Minerals, Gemstones, and Chemical Compounds
|
|||
BeO (Extreme Poison) | Red Beryl – Be3Al2Si6O18 | Blue Beryl – Be3Al2Si6O18 | Heliodor – Be3Al2Si6O18 |
Six (6) Chemical State Tables of Be (1s) 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.
Table #1
Be (1s) 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 NIST BE | Hydrocarbon C (1s) BE |
Source |
Be | 4 | Be – element | 111.8 eV | The XPS Library | ||
Be | 4 | Be-O (N*4) | 113.7 eV | 114 eV | 284.8 | Avg BE – NIST |
Be | 4 | Be-O | 113.5 eV | 285.0 | The XPS Library | |
Be | 4 | Native BeOx | 114.8 eV | 286.3 | The XPS Library | |
Be | 4 | Be-F2 (N*2) | 115.3 eV | 116.1 eV | 284.8 | Avg BE NIST |
Be | 4 | Be-F2 | 116.4 eV | 285.0 | The XPS Library | |
Be | 4 | Be-(OH)2 | The XPS Library | |||
Be | 4 | Be-CO3 | The XPS Library | |||
Be | 4 | Be-SO4 | The XPS Library | |||
Be | 4 | Be-l2 | 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)
Table #2
Be (1s) Chemical State BEs from: “PHI Handbook”
C (1s) BE = 284.8 eV
Copyright ©: Ulvac-PHI
Table #3
Be (1s) Chemical State BEs from: “Thermo-Scientific Website”
C (1s) BE = 284.8 eV
Chemical state | Binding energy, Be (1s) |
CuxBey as-received | 113.3 eV |
CuxBey Ar+ cleaned | 112.5 eV |
Copyright ©: Thermo Scientific
Table #4
Be (1s) Chemical State BEs from: “XPSfitting Website”
Chemical State BE Table derived by Averaging BEs in the NIST XPS database of BEs
C (1s) BE = 284.8 eV
Copyright ©: Mark Beisinger
Table #5
Be (1s) 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
|
Histograms of NIST BEs from Be (1s)
Important Note: NIST Database defines Adventitious Hydrocarbon C (1s) BE = 284.8 eV for all insulators.
Histogram indicates: 111.6 eV for Be0 based on 3 literature BEs | Histogram indicates: 113.8 eV for BeO based on 4 literature BEs |
Table #6
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 |
---|---|---|---|---|
Be | 1s | Be | 111.30 | Click |
Be | 1s | Be | 111.60 | Click |
Be | 1s | Be | 111.80 | Click |
Be | 1s | Be | 111.82 | Click |
Be | 1s | BeO | 113.70 | Click |
Be | 1s | BeO | 113.70 | Click |
Be | 1s | BeO | 113.70 | Click |
Be | 1s | BeMoO4 | 113.70 | Click |
Be | 1s | BeRh2O4 | 113.80 | Click |
Be | 1s | BeO | 114.00 | Click |
Be | 1s | Na2BeF4 | 114.70 | Click |
Be | 1s | BeF2 | 115.30 | Click |
Be | 1s | NaBeF3 | 115.30 | Click |
Be | 1s | BeF2 | 116.10 | Click |
Statistical Analysis of Binding Energies in NIST XPS Database of BEs
Advanced XPS Information Section
Spectra, BEs, Features, Guidance and Cautions
for XPS Research Studies on Beryllium Materials
from Common Beryllium Compounds
Be (1s) = 111.8 eV: Beo Cu (2p3/2) BE = 932.65 eV |
Be (1s) 113.5 eV: BeO C (1s) BE = 285.0 |
Be (1s) = 116.4 eV: BeF2 C (1s) BE = 285.0 eV |
Features Observed
- xx
- xx
- xx
Overlay of Be (1s) Spectra shown Above
C (1s) BE = 285.0 eV
Plasmon Peaks from Beryllium Metal, Beo
Fresh exposed bulk produced by extensive Ar+ ion etching
Be (1s) – Plasmon Peaks – Extended Range Spectrum | Be (1s) – Plasmon Peaks -Extended Range Spectrum – Vertically Zoomed |
Features Observed
- xx
- xx
- xx
Native Oxide on Beryllium, Beo Metal
Naturally Formed at 25 Co 1 atm
Survey Spectrum from FRESH Native Oxide on Beo metal | Be (1s) Chemical State Spectrum from FRESH Native Oxide on Beo |
|
|
O (1s) Chemical State Spectrum from FRESH Native Oxide on Beo | C (1s) Chemical State Spectrum from FRESH Native Oxide on Beo |
Features Observed
- xx
- xx
- xx
Flood Gun Effect on Native Oxide of Beryllium
Native Oxide of Beryllium Disk – Sample GROUNDED
versus
Native Oxide of Beryllium Disk – Sample FLOATING
Native Oxide of Beryllium Disk – Sample Grounded
Electron Flood Gun: 0 Voltage (FG OFF), Min Voltage versus Max Voltage |
||
Be (1s) | O (1s) | C (1s) |
Differential Shift of BeO Peak is due to Differential Charging |
Differential Shift of O (1s) Peak is due to Differential Charging |
Differential Shift of Adventitious Carbon is a Slightly Larger |
Native Oxide of Beryllium Disk – Sample Floating Electron Flood Gun: 0 Voltage (FG OFF), Min Voltage versus Max Voltage |
||
Be (1s) | O (1s) | C (1s) |
All Peaks Shift Linearly NO Differential Charging |
All Peaks Shift Linearly NO Differential Charging |
All Peaks Shift Linearly NO Differential Charging |
XPS Spectra
from Common Beryllium Compounds
Beryllium Oxide (BeO)
pressed pellet
Survey Spectrum from BeO | Be (1s) Chemical State Spectrum from BeO |
|
|
O (1s) Chemical State Spectrum from BeO |
C (1s) Chemical State Spectrum from BeO |
Features Observed
- xx
- xx
- xx
Valence Band Spectra
Beo, BeO
Beo metal Ion etched clean |
BeO powder Charge Referenced so C (1s) = 285.0 eV |
Features Observed
- xx
- xx
- xx
Be (1s) Signal
|
O (1s) Signal | C (1s) Signal |
Chemical State Depth Profile on Thin Beryllium Oxide
from JEOL 7830F Auger
Thin oxide produced by dipping clean Be metal into HNO3 for 60 sec
Be KLL Signal: BeO at front -> Be metal at rear (normal display) | O KLL Signal: BeO at rear -> Be metal at front (display reversed) |
Features Observed
- xx
- xx
- xx
Chemical State Spectra from
Chemical Compounds or Alloys
that include Beryllium
Beryllium Alloys
XxCu | XxCu |
→ Periodic Table | |
XxCu | XxCu |
Copyright ©: The XPS Library
XPS Facts, Guidance & Information
Element | Beryllium (Be) |
||||
Primary XPS peak used for Peak-fitting : | Be (1s) | ||||
Spin-Orbit (S-O) splitting for Primary Peak: | NO Spin-Orbit splitting for “s” orbitals |
||||
Binding Energy (BE) of Primary XPS Signal: | 111.8 eV |
||||
Scofield Cross-Section (σ) Value: | Be (1s) = 0.1947 |
||||
Conductivity: | Metal form is conductive Resistivity = 36 nΩ⋅m (at 20 °C) Native Oxide suffers Differential Charging |
||||
Range of Be (1s) Chemical State BEs: | 111.8 – 115.0 eV range (Beo to BeF2) | ||||
Signals from other elements that overlap Be (1s) Primary Peak: |
?? | ||||
Bulk Plasmons: | ~20 eV above peak max for pure metal | ||||
Shake-up Peaks: | ?? | ||||
Multiplet Splitting Peaks: | not possible | ||||
|
|
General Information about XXX Compounds: |
xx | ||
Cautions – Chemical Poison Warning |
Be metal gas and BeO powder are toxic if breathed extensively. Be extremely careful using BeO powder. |
Copyright ©: The XPS Library
Information Useful for Peak-fitting Be (1s)
- FWHM (eV) of Be (1s) from Pure Be metal: ~0.69 eV using 50 eV Pass Energy after ion etching:
- FWHM (eV) of Be (1s) from BeO: ~1.73 eV using 50 eV Pass Energy (before ion etching)
- Binding Energy (BE) of Primary Signal used for Measuring Chemical State Spectra: 111.8 eV for Be (1s) with +/- 0.1 uncertainty
- List of XPS Peaks that can Overlap Peak-fit results for Xx (1s): xx
General Guidelines for Peak-fitting XPS Signals
- Typical Energy Resolution for Pass Energy (PE) setting used to measure Chemical State Spectra on Various XPS Instruments
- Ag (3d5/2) FWHM (eV) = ~0.95 eV for PE 50 on Thermo K-Alpha
- Ag (3d5/2) FWHM (eV) = ~1.00 eV for PE 80 on Kratos Nova
- Ag (3d5/2) FWHM (eV) = ~0.95 eV for PE 45 on PHI VersaProbe
- FWHM (eV) of Pure Elements: Ranges from 0.4 to 1.0 eV across the periodic table
- FWHM of Chemical State Peaks in any Chemical Compound: Ranges from 1.1 to 1.6 eV (in rare cases FWHM can be 1.8 to 2.0 eV)
- FWHM of Pure Element versus FWHM of Metal Oxide: Pure element FWHM << Metal Oxide FWHM (e.g. 0.8 vs 1.5 eV, roughly 2x)
- If FWHM Greater than 1.6 eV: When a peak FWHM is larger than 1.6 eV, it is best to add another peak to the peak-fit envelop.
- BE (eV) Difference in Chemical States: The difference in chemical state BEs is typically 1.0-1.3 eV apart. In rare cases, <0.8 eV.
- Number of Peaks to Use: Use minimum. Do not use peaks with FWHM < 1.0 eV unless it is a metal or a conductive compound.
- Typical Peak-Shape: 80% G: 20% L, 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 on Peak-fitting: ??
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.
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.
Contaminants Specific to Beryllium Metal
- Beryllium metal develops a thick native oxide due to the reactive nature of clean Beryllium metal.
- The native oxide of BeOx is 6-7 nm thick.
- Beryllium metal thin films often have a low level of iron (Fe) in the bulk as a contaminant or to strengthen the thin film
- Beryllium forms a low level of carbide when the surface is ion etched inside the analysis chamber
Commonplace Contaminants
- Carbon and Oxygen are common contaminants that appear on nearly all surfaces. The amount of Carbon usually depends on handling.
- Carbon is usually the major contaminant. The amount of carbon ranges from 5-50 atom%.
- Carbon contamination is attributed to air-borne organic gases that become trapped by the surface, oils transferred to the surface from packaging containers, static electricity, or handling of the product in the production environment.
- Carbon contamination is normally a mixture of different chemical states of carbon (hydrocarbon, alcohol or ether, and ester or acid).
- Hydrocarbon is the dominant form of carbon contamination. It is normally 2-4x larger than the other chemical states of carbon.
- Carbonate peaks, if they appear, normally appear ~4.5 eV above the hydrocarbon C (1s) peak max BE.
- Low levels of carbonate is common on many metals that readily oxidize in the air.
- High levels of carbonate appear on reactive metal oxides and various hydroxides. This is due to reaction between the oxide and CO2 in the air.
- Hydroxide contamination peak is due to the reaction with residual water in the lab air or the vacuum.
- The O (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 metals. Carbides form due to the residual CO and CH4 in the vacuum.
- Ion etching can produce low oxidation states of the material being analyzed. These are newly formed contaminants.
- Ion etching polymers by using standard Ar+ ion guns will destroy the polymer, converting it into a graphitic type of carbon
Data Collection Guidance
- Chemical state differentiation can be difficult
- Collect principal Be (1s) peak.
- 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
Data Collection Settings for Beryllium (Be)
- Conductivity: Beryllium 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: Be (1s) at 111.8 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: 105 – 125 eV
- Recommended Extended BE Range for Measuring Chemical State Spectrum: 100 – 150 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
Effects of Argon Ion Etching
- Carbides can appear after ion etching various reactive metals. Carbides form due to the residual CO and CH4 in the vacuum.
- Ion etching can produce low oxidation states of the material being analyzed. These are newly formed contaminants.
- Ion etching polymers by using standard Ar+ ion guns will destroy the polymer, converting it into a graphitic type of carbon
End of File