Improved background-fitting algorithms for ionization edges in electron energy-loss spectra

We discuss improved procedures for fitting a power-law background to an ionization edge in an electron energy-loss spectrum. They place constraints on the background, both above and below the ionization-threshold energy, and are of particular advantage in the case of weak edges arising from low elemental concentrations. The algorithms are currently implemented as short Calculator programs for Gatan EL/P software. Their advantages and limitations are discussed, in comparison with multiple-least-squares and spatial-difference techniques.