The SmartEFTEM-SI method: Development of a new spectrum-imaging acquisition scheme for quantitative mapping by energy-filtering transmission electron microscopy

A new acquisition scheme for energy-filtering transmission electron microscopy (EFTEM) spectrum-imaging (SI), named SmartEFTEM-SI, has been developed. The new method reduces the influence of CCD dark-current modulations on energy-filtered images and enables improved spatial-drift correction. In conventional EFTEM approaches, elemental maps are significantly degraded especially when these issues are not addressed. The new scheme also offers multiple-frame acquisition at individual energy planes, and the acquisition of a low-loss SI dataset immediately following the high-loss SI dataset recorded for a particular characteristic edge, enabling advanced spectral processing such as multiple-scattering deconvolution and thickness correction. After spectral processing of the high-loss SI datasets using the corresponding low-loss information, the absolute number of atoms of the particular element of interest can be determined. The SmartEFTEM-SI method thus offers absolute elemental quantification of a thin specimen over a large field of view.

► A new acquisition scheme for energy-filtered TEM spectrum imaging, called SmartEFTEM-SI, has been developed.
► Initialization and ad hoc correction of CCD dark-current are incorporated.
► Improved spatial-drift correction can be applied using zero-loss filtered images acquired successively between filtered images.
► Multiple-frame acquisition is applicable to improve signal-to-noise ratio.
► Appropriate spectral processing and absolute quantification can be performed for EFTEM maps.