Optimizing EELS acquisition

A method for spectral acquisition, called binned gain averaging, will be described and tested. Systematic or correlated noise is efficiently suppressed with this method by averaging the gain over a series of CCD pixels. As a result, improved signal-to-noise ratios are obtained that allow the detection of very weak signals. At the same time, the spectral energy resolution is not degraded—even for long acquisition periods. It will be demonstrated that with this method, it is possible to significantly enhance the acquisition speed and quality of electron energy-loss (EEL) spectra and EELS maps. Examples will be given of double ionic scattering (i.e. the detection of the second boron K-edge) and the mapping of gold surface plasmons in the near-infrared and visible energy range.