# L-edge of absorption

What is the L-edge of absorption? For example, Si has its L2,3 edge at 99.8 eV? The second atomic shell is L, but what does 2,3 mean?

Thanks

Bob S
The k-edge and L edge of an atom refers to the minimum energy (or maximum wavelength) photon (UV or x-ray) that can remove an (photo) electron from the K or L shells (usually meaning ionize), such that other bound electrons cascade down to fill the vacancies. The photon energies correspond to "edges" in a plot of photon attenuation vs. photon energy where there is a sudden large increase in the attenuation coecfficient. Figure 1 in this reference shows a k-shell photoelectron ejection, with the possible atomic electron cascades.
L(2,3) may refer to the electron transition that fills the L shell vacancy (M-shell to L-shell)

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