Sulfur

Sulfur • Non-Metals

Primary XPS region: S2p
Overlapping regions: Si2s plasmon, Se3p
Binding energies of common chemical states:

Charge referenced to adventitious C1s peak at 284.8 eV.

• It is not advisable to analyze pure sulfur, as the vapor pressure may result in contamination of adjacent samples and discoloration of copper surfaces.
• Sulfur-containing self-assembled monolayers (SAMs) may be damaged by exposure to X-rays.
  • Sulfur content is very low and typically requires long acquisition time for good quality S2p spectrum.
  • For spatially uniform samples, minimize X-ray exposure per unit area by acquiring an array of well separated points (linescan or map) with very short acquisition times per point.
  • Total acquisition time for array of points should be sufficient for good signal-to-noise when the array is integrated into a single dataset.

• S2p peak has closely spaced spin-orbit components (Δ=1.16eV, intensity ratio=0.511).
  • Effect of spin-orbit splitting can be observed for sulfur elements and compounds.
• The user typically observes either splitting between components or asymmetric peak shape due to unresolved doublet, depending on chemical state and/or instrument resolution.

• S2s peak, like S2p, shows a large range of chemical shifts.
  • S2s peak has strong overlap with Se3s peak and Mo3d (particularly in sulfate/sulfonate chemical states, see Molybdenum section).

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