Choose suitable edges for quantification

Once you select the element of interest, it is important to choose a suitable edge to analyze. Key variables to consider:

  • Is the edge energy suitable?

    • Low energies (<150 eV) – It may be difficult to extract a signal because of other low-loss features (e.g., plasmons) overlapping with the edge

    • High energies (≥2000 eV) – Edges tend to be noisier, but may be easier to remove background from

  • What is the accuracy of the edge?

    • K-, L-edges

      • Small cross-sections (→low signal-to-noise ratio)

      • Not suitable for high Z elements (ionization energy too high)

      • However, software can compute cross-sections relatively accurately

    • M-, N-, O-edges

      • Larger cross-sections

      • Higher Z elements only

      • Less reliable computed cross-sections

  • Presence of other edges in spectrum (e.g., overlapping edges) that may make it difficult to accurately analyze your edge

In general, using the highest energy edge that still give sufficient signal is recommended.

References

Leapman, R. D.; Rez, P.; Mayers, D. F. K, L and M shell generalized oscillator strengths and ionization cross-sections for fast electron collisions. J. Chem. Phys. 72:1232 – 1243; 1980.