A quantitative evaluation of the 2nd derivative mode in electron energy loss spectroscopy

The second derivative mode of peak analysis in electron energy loss spectroscopy (EELS) in a Transmission Electron Microscope (TEM) has been quantitatively evaluated in terms of the accuracy of the method. This includes a demonstration of the importance of the second derivative peak width, the second order dependency of the accuracy upon that peak width and effect of high frequency noise in the spectra. It is shown that while the second derivative method is an efficacious and powerful mode of analysis, there are limitations in terms of the number of significant digits in both the spectral values and derived electronic quantities. The case of uranium N_4,5 spectral peaks and the 5f population is presented as an example, with UO₂ X-ray Absorption Spectroscopy used as a benchmark.