One of the atomic-focuser modes for ultra-high resolution electron microscopy is described theoretically and illustrated by the observation of images formed within the diffraction spots of nanodiffraction patterns of carbon nanoshells. In this mode, the specimen is illuminated by the focused probe of a scanning transmission electron microscope and is followed by a thin crystal at a Fourier-image distance. The theory shows that each diffraction spot of the crystal contains a magnified image of the illuminated area of the specimen, having a resolution depending on the width of the intensity peak of electrons channeled along atomic rows in the crystal. A thin graphite crystal, contained within one wall of a carbon nanoshell, can act as an atomic focuser to image part of the other wall of the nanoshell, or tungsten atoms deposited on this wall. Simulations of the transmission of electrons through graphite crystals show that the images formed should have a resolution of about 0.06 nm. Experimental images suggest that this resolution has been attained in the imaging of tungsten atoms or clusters of tungsten atoms.

The three-dimensional (3D) atom-probe technique produces a reconstruction of the elemental chemical identities and three-dimensional positions of atoms field evaporated from a sharply pointed metal specimen, with a local radius of curvature of less than 50 nm. The number of atoms collected can be on the order of one million, representing an analysis volume of approximately 20 nm × 20 nm × 200 nm (80,000 nm3). This large amount of data allows for the identification of microstructural features in a sample, such as grain or heterophase boundaries, if the feature density is large enough. Correlation of the measured atomic positions with these identified features results in an atom-by-atom description of the chemical environment of crystallographic defects. This article outlines a data compilation technique for the generation of composition profiles in the vicinity of interfaces in a geometrically independent way. This approach is applied to quantitative determination of interfacial segregation of silver at a MgO/Cu(Ag) heterophase interface.

The results of a three-dimensional atom probe (3DAP) analysis, on a subnanometer scale, of a ceramic/metal heterophase interface, MgO/Cu, are presented. Segregation of Ag, from the Cu (Ag) matrix, at MgO/Cu interfaces is investigated and the Gibbsian interfacial excess of silver is determined; the range is 2.33 × 1018 to 5.81 × 1018 m−2. Also, silver segregation at the same MgO/Cu interfaces is analyzed employing a new approach that utilizes a proximity histogram or proxigram.

Transmission electron microscope samples of two types of metal matrix composites were prepared using both traditional thinning methods and the more novel focused ion beam miller. Electropolishing methods were able to produce, very rapidly, thin foils where the matrix was electron transparent, but the ceramic reinforcement particles remained unthinned. Thus, it was not possible in these foils to study either the matrix-reinforcement interface or the microstructure of the reinforcement particles themselves. In contrast, both phases in the composites prepared using the focused ion beam miller thinned uniformly. The interfaces in these materials were clearly visible and the ceramic reinforcement was electron transparent. However, microstructural artifacts associated with ion beam damage were also observed. The extent of these artifacts and methods of minimizing their effect were dependent on both the materials and the milling conditions used.

Magnetotactic bacteria from aquatic environments were analyzed with the electron spectroscopic imaging technique. Rod-shaped bacteria and cocci were present in most of the samples observed. Magnetotactic multicellular aggregates were also observed at some of the sampling sites. The use of electron spectroscopic imaging allowed the observation of magnetosomes inside magnetotactic microorganisms with exceptional clarity. The number, size, and morphology of magnetosomes, as well as their ultrastructural spatial disposition inside the bacterial cell, could be directly observed and associated with the disposition of flagella of the respective cells.This allowed us to examine the structural relationships between magnetosomes and flagella, which are important components in the mechanisms of magnetotaxis. In disrupted magnetotactic multicellular aggregates, connections between cells were also visualized. We believe this technique will be useful in studying not only magnetotactic bacteria but also other uncultured microorganisms from natural environments.

The interference pattern obtained from a multiple internal reflection of a spermatozoon, sandwiched between the glass plate and the cover plate, was focused on the objective of a scanning confocal microscope. According to optical path differences, morphological details were revealed. The combined features, namely improved resolution in z axis, originating from the interference pattern and the optical sectioning of the confocal scanning system, enhanced the resolution and contrast in an impressive manner. These features permitted unprecedented images of the spermatozoon to be obtained at 0.1 μm optical sectioning and reconstruction of three-dimensional (3-D) images. With the help of optical sectioning, it was possible to estimate the thickness and the morphological details of the spermatozoon.