Multiple least-squares fitting for quantitative electron energy-loss spectroscopy — an experimental investigation using standard specimens

Use of multiple least-squares fitting of EEL spectra for quantitative purposes is investigated from an experimental point of view using test specimens of different thicknesses and different carbon and calcium content. A good agreement, with some limitations, between measured and fitted spectra is show for pure carbon films and mixed carbon/calcium fluoride specimens. The reliability of thickness determination from carbon peak EEL spectra is demonstrated and the applicability on spectra from non-pure compounds is evaluated. Experimental partial scattering cross sections δx (11 mrad, 50 eV) for the CK and the CaL2,3 edge are calculated and used to convert edge integral ratios to real elemental ratios. The linearity between the element contribution coefficients in the multiple least-squares approach and the real elemental ratios is shown experimentally. The reliability of this method for the determination of Ca/C ratios is investigated and the limitations are discussed, considering the peculiarities of serial TEM-EELS.