Spatial resolution in EFTEM elemental maps

Abstract

SUMMARY Imaging filters developed over the last few years permit rapid elemental mapping by energy‐filtering transmission electron microscopy (EFTEM), with resolution and sensitivity limited primarily by the sample and by the TEM. We explore the attainable spatial resolution in the elemental maps theoretically and experimentally, and suggest optimized set‐up procedures for maximizing the resolution. The chromatic aberration of the objective lens of the microscope is shown to be a major limit. Its influence can be minimized by using small energy intervals and limited collection angles, but this is done at the cost of decreased collection efficiency. Resolution of better than 1 nm and sensitivities to less than a monolayer of elements with favourable edges are readily attainable in elemental maps obtained with acquisition times of 40 s total and less. Resolution better than 0·5 nm should be attainable with further optimization of the acquisition parameters.

Plasmon-loss imaging of polymer-methanofullerene bulk heterojunction solar cells

“…P3HT fibres of diameter $6 nm and above are resolved in the tomograms. For the experimental conditions used in this study (i.e., no objective aperture) the theoretical spatial resolution 19 for the plasmon-loss image is estimated to be $5 nm, with the dominant contribution being chromatic aberration of the objective lens. The best attainable resolution is $2 nm for a 10 mrad objective aperture; in this new regime plasmon delocalisation is the limiting factor.…”

Direct Evidence for Block-by-Block Growth in High-Temperature Superconductor Ultrathin Films

“…Complementary, real space measurements of characteristic innershell excitations at high spatial resolution provide conclusive support for the chemical and structural details of the superlattices and their interfaces. These measurements are readily implemented in modern energy-filtering transmission electron microscopes (EFTEM) and, depending on the microscope parameters and the elements of interest, lateral resolution below 1 nm can be achieved [14][15][16][17]. All EFTEM investigations were performed using cross-section samples on a Philips CM200͞FEG equipped with a field emission source and a post-column energy filter (Gatan Imaging Filter, GIF).…”

Energy-filtering TEM at high magnification: spatial resolution and detection limits

“…Far more than in high-resolution TEM, the attainable spatial resolution in EFTEM is influenced by the experimental setup: The energy and the shape of the ionization edge, as well as experimental parameters like the collection angle, influence the obtainable resolution together with instrumental parameters (aberration coefficients of the TEM objective lens) [6,14,15]. For instance, delocalization is one of the main factors influencing spatial resolution at low energy-losses.…”

“…In EFTEM, post-column energy filters in combination with high resolution TEMs can provide the capability to detect small features, like thin layers or small particles, down to subnanometer dimensions [1][2][3][4][5][6][7][8][9][10]. (Other groups also tried to reach nm-resolution but either the results were contradictory or not quite unequivocal [11][12][13].)…”