AN EFFICIENT METHOD FOR CALCULATING THE LEAST-SQUARES BACKGROUND FIT IN ELECTRON-ENERGY-LOSS SPECTROSCOPY

In quantitative electron energy-loss spectroscopy, an estimate has to be made of the unspecific spectral background to obtain the element-sp ecific contribution of an ionization edge. For energy losses above c. 100 eV, such a background estimate is commonly performed by calculatin g the least-squares fit of a power-law model to a part of the pre-edge region of the spectrum and by extrapolating this model to the region beyond the edge. Existing methods are cumbersome in terms of computati on time and stability, or yield biased estimates. Computation efficien cy becomes important when processing spectral-image sequences. In this paper a new, computationally efficient numerical method is presented, which appears to be extremely robust in practice.