Plasmon energy mapping in energy-filtering transmission electron microscopy

Prior research has shown that plasmon energy can be used to distinguish material phases in electron microscopy. However, no prior work had resolved how to map plasmon energies across a sample with high precision. Established methods rely on spectroscopy, which lacks spatial resolution. This gap motivated the development of energy-filtered imaging techniques. It was already known that plasmon energy varies with material composition and structure. Yet, the non-isochromaticity of energy filters remained an unresolved issue. This uncertainty drove the need for a method that could map plasmon energies in two dimensions. The study addresses this by applying energy-filtering transmission electron microscopy to nanostructured materials.

The aim of this study is to demonstrate a technique for two-dimensional plasmon energy mapping using energy-filtering transmission electron microscopy. The specific problem addressed is the lack of spatially resolved plasmon energy data in complex materials. The motivation stems from the need to identify distinct phases in nanocrystalline ceramics. The researchers propose that energy-filtered images can provide such resolution. They also aim to visualize and correct non-isochromaticity in electron filters. This approach allows for material identification based on plasmon energy signatures. The study focuses on a Si-B-C-N ceramic with multiple phases. The results may suggest a way to improve spatial accuracy in electron microscopy.

The researchers used energy-filtering transmission electron microscopy to capture plasmon energy maps. They acquired a series of energy-filtered images in the plasmon energy region. The method involved scanning a nano-crystalline Si-B-C-N ceramic sample. The material contained SiC, Si(3)N(4), h-BN, and t-C phases. The technique relied on detecting specific plasmon energies for each phase. An energy resolution of less than or equal to 0.1 eV was achieved. The study also examined an amorphous carbon film to assess filter performance. A correction procedure was proposed for the non-isochromaticity of the Corrected Omega filter.

The strongest finding is that plasmon energy maps can distinguish SiC, Si(3)N(4), h-BN, and t-C phases in the ceramic. The energy resolution reached 0.1 eV or better. The maps showed distinct energy signatures for each material phase. The intergranular regions were identified as h-BN and t-C. The study demonstrated that plasmon energy mapping can provide spatially resolved data. The non-isochromaticity of the Corrected Omega filter was visualized using an amorphous carbon film. A correction procedure was proposed to address this issue. The results suggest that energy-filtered imaging can improve material identification in electron microscopy.

The authors state that plasmon energy mapping can identify distinct phases in nanocrystalline materials. They propose that energy-filtered images provide spatial resolution for material analysis. The study shows that plasmon energy signatures can distinguish SiC, Si(3)N(4), h-BN, and t-C. The energy resolution achieved is sufficient for phase identification. The non-isochromaticity of the Corrected Omega filter was observed in the amorphous carbon film. A correction method was suggested to improve filter performance. The findings may suggest that this technique can enhance material characterization. The authors conclude that energy-filtering transmission electron microscopy is suitable for plasmon energy mapping.