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Examples of Microanalysis in the TEM
Spectrum Imaging Using SmartMap™ in INCAEnergyTEM
Modern EDS systems offer spectrum imaging, where all X-ray information
detected during an X-ray map collection is saved. In this way a full X-ray
spectrum is acquired and stored for every pixel in the map and used to
investigate further aspects of the chemistry of the sample during or after
the acquisition. The main advantage of analyzing samples in this fashion is
that minimal knowledge of the sample composition is required prior to X-ray
analysis since all X-ray data is collected. For example, there is no need to
define specific energy windows for mapping before collecting the data as
this can be done during or after the acquisition. It is important that X-ray
maps are dead time corrected, so any changes in count rate due to variation
of sample thickness or beam intensity are correctly represented and no
associated artifacts are created in the maps.
The spectrum image data in INCAEnergyTEM is referred to as a SmartMap and
the software provides a series of tools for reconstructing spectra,
linescans and maps from a single SmartMap. For example, a SmartMap has been
collected from a two phase ceramic sample consisting of aluminium oxide and
titanium carbide. The collected datacube contains 2.5 million X-rays and was
acquired for 30 minutes. Data from the SmartMap file has been used to
reconstruct X-ray maps for the major elements in the sample: including
titanium (orange), and aluminium (green) (Figure 8). Representative spectra
describing the different phases clearly identify the aluminum oxide and
titanium carbide.
Spectra have been reconstructed from 20nm square areas across a TiC grain to
study the chemistry at grain boundaries in this ceramic material (Figure 9).
Using the quantitative linescan software in INCAEnergyTEM, the chemistry
variations across these grain boundaries can be determined (Figure 10).
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