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Intensity Vs. Binding Energy - XPS Interpretation
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Intensity Vs. Binding Energy - XPS Interpretation

XPS Spectrum Analysis

Overview of XPS Spectrum Information

  • The XPS spectrum provides two critical types of information: intensity (counts per second) on the Y-axis and binding energy on the X-axis.
  • The binding energy is represented as peak positions, while peak intensity indicates the quantity of elements present in the sample.

Understanding Survey Spectrum

  • The survey spectrum ranges from 0 to 1200 eV, indicating it is a surface spectrum. Peaks are convoluted, suggesting multiple electronic states.
  • Notably, doublets are absent in this spectrum, reinforcing its classification as a surface spectrum.

Binding Energy Insights

  • The X-axis represents peak position or binding energy; this is crucial for identifying elemental composition.
  • Binding energy acts like a fingerprint for elements; shifts in peaks indicate changes in oxidation state and chemical environment.

Oxidation State and Chemical Environment

  • Changes in peak positions reflect variations in oxidation states; leftward shifts indicate increases while rightward shifts suggest decreases.
  • The chemical environment influences binding energies based on electronegativity; higher electronegativity leads to increased electron pull and higher binding energies.

Peak Intensity Analysis

  • The Y-axis measures peak intensity, which quantitatively reflects the concentration of specific elements within the sample.
  • Larger areas under peaks signify greater amounts of an element present; smaller areas indicate lesser quantities.

Elemental Concentration Determination

  • Higher intensities typically arise from p, d, or f orbitals due to their larger electron counts.
  • XPS effectively analyzes surface concentrations up to 10 nm deep, providing insights into elemental distributions such as iron oxide concentrations.
Playlists: XPS - X-rays Photoelectron Spectroscopy
Video description

Interpretation of XPS Spectrum: Intensity Vs. Binding Energy (BE) The XPS spectrum provides two sets of information: The XPS detector detect and SEPARATE photoelectrons & Auger electrons in ENERGY and Counted. Simply, the BE on x-axis & Intensity (Counted electrons) on the y-axis form the XPS spectrum. 1. The x-axis: Peak position / BE / Kinetic Energy(KE) The peak position on the x-axis indicates the BE in eV, which can be used to identify the types of elements exist on the surface (~10 nm thickness). The qualitatively information i.e., types of elements (Pb, Fe, C, O, Ag, Cl, Au, Ni, Cu, Co.......) can be obtained from the BE value. Other information such as the oxidation states, the chemical environment, the bonding atoms can also be identified from the x-axis BE value. A shift (left or right) in the peak position or BE value means that the oxidation state of the elements changes. For instance, if the Nitrogen or Florine bonded with Oxygen, the Nitrogen or Florine atoms pulls more electrons from oxygen and the BE value or peak position for oxygen atom would shifts toward the higher value. 2. The y-axis: Peak intensity /Shape / Counted The peak intensity determine the concentration of chemical elements i.e., shows how much amount of the specific elements exists on the surface. It reveals the information quantitatively. The higher the intensity of the peak, the more is the number of electrons detected. Intensity simply means the area under the curve. It displays the total number of electrons counted or detected per second. PS: Actually, the XPS detect the KE of the photoelectrons but then we calculate the BE = hv-KE-WF (work function). Moreover, traditionally the XPS spectrum is plotted Intensity vs. KE If you find the topic interesting, please like it and subscribe to my channel. Thank you very much!