Quantitative Position-AveragedK-,L-, andM-Shell Core-Loss Scattering in STEM

Abstract

We present a quantitative comparison between experimental position-averaged core-loss scattering from K-, L-, and M-shells of various elements and simulations based on a single-particle description of the core-loss process. To facilitate a direct comparison free of adjustable or compensating parameters, we compare absolute scattering cross-sections for zone-axis-aligned crystals whose thicknesses have been measured independently. The results show that the single-particle model accurately predicts the absolute scattering intensity from K-shells, and L-shells in some cases, but achieves only semi-quantitative agreement for M-shells.

Accuracy and precision of thickness determination from position-averaged convergent beam electron diffraction patterns using a single-parameter metric

“…Table 1 summarises the thickness determination and uncertainty ranges, expressed as asymmetric error margins above and below the determined thickness, for the (energy filtered) PACBED patterns from all seven areas on the specimen. For the thinner samples at least, the error margin is consistent with the 1 or 2 nm error margin often quoted for thickness determination [8,37,43]. The table further shows that the error margins tend to grow with increasing specimen thickness, consistent with the visual impression from Fig.…”

Precipitation of a new platelet phase during the quenching of an Al-Zn-Mg-Cu alloy

“…While there is clear structural similarity between the Y-phase and the T 1 phase 23 , alloy 7150 contains no Li so the chemistry of this phase must be substantially different. Due to electron channelling in crystalline specimens, quantitative chemical analysis on these length scales is not possible without a full solution of the atomic structure 25 and precise knowledge of acquisition geometry 26 . However, both the EDX and EELS results from the plates give a qualitative indication of the chemical makeup of, and to some extent, the partitioning within the precipitate plates.…”

Quantification and optimization of ADF-STEM image contrast for beam-sensitive materials

“…In general, fewer electrons are scattered to high angles, as schematically depicted in figure 1 b . The use of small inner collection angles improves the SNR significantly, while at the same time, at fairly low scattering angles, crystalline and semi-crystalline materials are subject to coherent effects like diffraction contrast [ 26 ], plasmon scattering [ 29 ], core-loss scattering [ 30 ] or contrast reversal (caused by multiple scattering of electrons within the specimen that leads to the scattered electrons ‘falling out' of the ADF detector) [ 13 , 18 , 31 ]. Therefore, it is necessary to know the minimum tolerable inner collection angle or angular range for which the image formation is still sufficiently incoherent.…”