Charge Referencing of insulators is defined such that the Adventitious Hydrocarbon C (1s) BE (eV) = 285.0 eV.The XPS Library uses Binding Energy Scale Calibration with Cu (2p 3/2) BE = 932.62 eV and Au (4f 7/2) BE = 83.98 eV.(N*number) identifies the number of NIST BEs that were averaged to produce the BE in the middle column.Ir (4f 7/2 ) Chemical State BEs from: “The XPS Library Spectra-Base”Īnd C (1s) BE = 284.8 eV for NIST BEs Element 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.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.Other BEs can be as low as 284.2 eV or as high as 285.3 eV Depending on your preference or training, the C (1s) BE assigned to this hydrocarbon peak varies from 284.8 to 285.0 eV.The hydrocarbon peak is normally the largest peak at the lowest BE.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. 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.Charge referencing is a common method, but it can produce results that are less reliable.Charge Referencing Methods for Insulators.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.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.This variation increases significantly above 600 eV BE.This range causes BEs in the higher BE end to be larger than expected.Some authors still adjust their energy scale so Cu (2p 3/2) appears between 932.2 eV or 932.8 eV because this is what the maker taught them.For various reasons authors still use older energy scale calibrations.Worldwide Differences in Energy Scale Calibrations.The accuracy depends on when the authors last checked or adjusted their energy scale to produce the expected calibration BEs.Different authors use different BEs for the C (1s) BE of the hydrocarbons found in adventitious carbon that appears on all materials and samples.Cu (2p 3/2) BE can vary from 932.2 to 932.8 eV for old publications The accuracy depends on the calibration BEs used to calibrate the energy scale of the instrument.Notes of Caution when using Published BEs and BE Tables from Insulators and Conductors: Six (6) Chemical State Tables of Ir (4f 7/2 ) BEs January 2022 – Transmission Function of Thermo K-Alpha Plus Survey Spectra of HOPG (C), PEs = 20, 50, 100 and 200 eV Survey Spectra of Ion Etched Copper (Sc), PEs = 100, 150 and 200 eVĪugust 2019 – Transmission Function of Thermo K-Alpha Plus March 2016 – Transmission Function of Thermo K-Alpha Plus Survey Spectra of Ion Etched Copper (Sc), PEs = 50, 100, 150 and 200 eV Ir (4f) Spectra – Overlay of Ir o and IrO xĭecember 2015 – Transmission Function of Thermo K-Alpha Plus Valence Band Spectra – Overlay of Ir o and IrO x Ir (4f) Spectrum from IrO x – Raw – Vertically Expandedįreshly exposed bulk, Flood gun is OFF, C (1s) BE = 284.3 eV, Ag FWHM = 0.75 eV Ir (4f) Spectrum from IrO x – Extended Range Survey, Peak-fits, BEs, FWHMs, and Peak Labelsįreshly exposed bulk, Flood gun is OFF, sample is conductive, Ag (3d 5/2) FWHM = 1.3 eVįresh exposed bulk, Flood gun is OFF, C (1s) BE = 284.3 eV, Ag FWHM = 0.75 eVįreshly exposed bulk, Flood gun is OFF, C (1s) BE = 284.3 eV, Ag FWHM = 0.75 eV Iridium native oxide (IrO x – Ir o at 300 C for 14 hrs ) Peak-fits are not fully optimized or designed to test any theory. Peak-fits are guides for practical, real-world applications. Atom% values are corrected for IMFP and PE. The XPS Spectra section provides raw and processed survey spectra, chemical state spectra, BE values, FWHM values, and overlays of key spectra.Ītom% values from surveys are based on sample, as received, and Scofield cross-sections.
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