Electron tomography at 2.4-ångström resolution

Abstract

Transmission electron microscopy is a powerful imaging tool that has found broad application in materials science, nanoscience and biology. With the introduction of aberration-corrected electron lenses, both the spatial resolution and the image quality in transmission electron microscopy have been significantly improved and resolution below 0.5 ångströms has been demonstrated. To reveal the three-dimensional (3D) structure of thin samples, electron tomography is the method of choice, with cubic-nanometre resolution currently achievable. Discrete tomography has recently been used to generate a 3D atomic reconstruction of a silver nanoparticle two to three nanometres in diameter, but this statistical method assumes prior knowledge of the particle's lattice structure and requires that the atoms fit rigidly on that lattice. Here we report the experimental demonstration of a general electron tomography method that achieves atomic-scale resolution without initial assumptions about the sample structure. By combining a novel projection alignment and tomographic reconstruction method with scanning transmission electron microscopy, we have determined the 3D structure of an approximately ten-nanometre gold nanoparticle at 2.4-ångström resolution. Although we cannot definitively locate all of the atoms inside the nanoparticle, individual atoms are observed in some regions of the particle and several grains are identified in three dimensions. The 3D surface morphology and internal lattice structure revealed are consistent with a distorted icosahedral multiply twinned particle. We anticipate that this general method can be applied not only to determine the 3D structure of nanomaterials at atomic-scale resolution, but also to improve the spatial resolution and image quality in other tomography fields.

Formation and Aggregation of Gold (Electrum) Nanoparticles in Epithermal Ores

“…Laboratory investigations have shown that gold [50,51] and silver [33] nanoparticles aggregate by a similar process of self-assembly to make fractal dendrites. In particular, the nanoparticles' aggregation is governed by a kinetically driven process called diffusion-limited aggregation (DLA) [33,51,52], which results in characteristic tree-like dendrites with similar fractal dimensions. Saunders and Schoenly [14,34] showed that dendrites in epithermal ores had similar fractal dimensions to those produced in the lab by gold nanoparticle aggregation, and they proposed that a modified DLA produced the natural fractal dendrites from the Sleeper deposit.…”

The properties of SIRT, TVM, and DART for 3D imaging of tubular domains in nanocomposite thin-films and sections

“…Finally, one advantage of WBP and SIRT are their easier implementation and use, whereas TVM and DART are sensitive to the reconstruction parameters and require expert knowledge for properly setting regularization parameters or ratio of boundary pixels, respectively. In summary, to determine which of the many possible reconstruction approaches, such as WBP [13], SIRT [26], TVM [23], DART [22], ART [27], EST [60], Directt [61], W-SIRT [62], is best for a particular class of samples, a study as the one presented here for tubular domains in a slab matrix should be carried out. 1 …”

Coherent X-ray diffractive imaging on the single-cell-level of microbial samples

“…Equal results have been obtained more quickly by using a centre of mass approach [270] in combination with the fact that the specimen here is isolated and that its support χ(x, y, z)…”