(XPS)-2 - Washington State University
(XPS)-2 - Washington State University (XPS)-2 - Washington State University
Chemical shift arises in the initial state from the displacement of the electroniccharge from the atom towards its ligands, reducing the electrostatic potential at theatom. There is a final state shift due to the polarization of the ligand by the core onthe central atom.Core electron BE in molecular systems exhibits chemical shifts which are simplyrelated to various quantitative measures of covalency. Greater the electronegativityof the ligands, the greater the BE of the core electron of the ligated atom.Basic concept: The core electrons feel an alteration inthe chemical environment when a change in thepotential (charge distribution) of the valence shelloccurs.For example: let’s assume that the core electrons areinside a hollow spherical charged shell. Each coreelectron then sees a potential V. A change in Q by ΔQgives a change in V.where ΔVisthechemical shiftΔV=R14πε0ΔQRCoreelectronsValence chargeQ
x 10 3Oxidized surfaces12Cr 2p ---data10CPS86Oxide peakElemental CrOxide peakElemental Cr4590 580 570Binding Energy (eV)Oxidized and clean Cr 2p spectra (left). Oxidized and clean Cu 2p spectra (right).The oxide layer resulted in extra peaks (shoulder at higher BE—left of the mainline). Satellites are also seen on the Cu 2p spectra.
- Page 5 and 6: Six features seen in a typical XPS
- Page 7 and 8: F 1s peakSharp Peak (core level)O 1
- Page 9 and 10: Vacancy created by photoionization
- Page 11 and 12: Shake-up satellites: distinct peaks
- Page 13: Auger featuresAuger electron emissi
- Page 17 and 18: Chemical BondingThe curve fitting o
- Page 19 and 20: Intensity ratio is given by (2j - +
- Page 21: Static Charging (cont.)Auger: Sampl
- Page 24 and 25: Peak Widths and IntensitiesPeak wid
- Page 26 and 27: Quantitative Analysis (cont.)Sx=( A
x 10 3Oxidized surfaces12Cr 2p ---data10CPS86Oxide peakElemental CrOxide peakElemental Cr4590 580 570Binding Energy (eV)Oxidized and clean Cr 2p spectra (left). Oxidized and clean Cu 2p spectra (right).The oxide layer resulted in extra peaks (shoulder at higher BE—left of the mainline). Satellites are also seen on the Cu 2p spectra.
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