Energies and Widths of Inner-Shell Levels

In this formula both inner-shell binding energy , and levelwidth F enter E denotes the energy of the photoelectron. 

So far, we have neglected photoabsorption due to excitation of an inner-shell electron to bound unoccupied levels. Photoexcitation processes occur already for photon energies below the ionization threshold. The corresponding excitation cross section a-e (e) is a sum of Lorentzian 

For an extraction of precise energy values from measured absorption edges additional information is required one may, for example, take the energy differences between the distinct bound and continuum levels from optical spectroscopy data of the next element (optical match, Z + 1 rule). With this method inner-shell binding energies have been determined with absolute accuracies of about The experimental binding energies 

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