Implementation of Gold deconvolution for enhanced energy resolution in EEL spectra.

Gold's iterative deconvolution algorithm has been applied to one-dimensional EEL spectra from hexagonal BN. The experimental resolution was varied from 1.1 to 2.25 eV and Gold's algorithm was able to restore low-loss and core-loss spectra overall well. To estimate the instrument response function, the most convenient method was to extract the zero-loss peak from the low-loss spectrum. By instead using low-loss spectra as kernel, as suggested by Egerton, enhanced energy resolution could also be obtained with plural scattering simultaneously removed. It is further shown how the FWHM of the π* peak in the boron K-edge of hexagonal BN is reduced from 1.4 to 0.7 eV with almost no noise amplification after 500 iterations while resolving the σ* doublet. The result was almost identical after a stunning 5000-10,000 iterations, implying that Gold's method converges and can be stable for a large number of iterations. However, for lower-intensity spectra the number of iterations is limited. The results close to the intense zero-loss peak were uncertain and further testing with better experimental resolution is recommended. It is also found that to improve the resolution and not just sharpen the spectra, a large number of iterations is required.