Showing papers in "Ultramicroscopy in 2015"

TL;DR: The ASTRA Toolbox provides an extensive set of fast and flexible building blocks that can be used to develop advanced reconstruction algorithms, effectively removing limitations in the geometrical parameters of the acquisition model and the algorithms used for reconstruction.

TL;DR: The method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe.

TL;DR: How the modelling of inelastic scattering has subsequently developed and how numerical implementation has been achieved is reviewed and a software package μSTEM is introduced, capable of simulating various imaging modes based on inelastically scattering in both scanning and conventional transmission electron microscopy.

TL;DR: It is shown that the ptychographic phase reconstruction method using pixelated detectors offers the highest contrast transfer efficiency and superior low dose performance compared to other STEM phase contrast modes including annular bright field (ABF) and differential phase contrast (DPC).

TL;DR: Two new approaches are introduced (1) a re-scanning approach using local pattern averaging and (2) using the multiple solutions obtained by the triplet indexing method, which provide an improvement in the resulting scan data.

TL;DR: A spin resolving "momentum microscope" is presented for the high resolution imaging of the momentum distribution of photoelectrons and the efficient mapping of the spin texture of the Au(111) surface state is demonstrated.

TL;DR: A versatile experimental setup is presented that enables performing correlative focused ion beam milling, transmission electron microscopy (TEM), and APT under optimized characterization conditions and it is demonstrated that atom probe tips can be characterized by TEM in the same way as a standard TEM sample.

TL;DR: The extent to which more established segmented detector geometries can instead be used to reconstruct a quantitatively good approximation to the projected specimen potential is explored.

TL;DR: The multislice approach described here treats the specimen as amorphous material which allows a straightforward implementation of the frozen phonon approximation and allows a large simulations that can include millions of atoms and keep the computer memory requirements to a reasonable level.

TL;DR: The width and shape of 10nm to 12 nm wide lithographically patterned SiO2 lines were measured in the scanning electron microscope by fitting the measured intensity vs. position to a physics-based model in which the lines' widths and shapes are parameters, agreeing with those determined by transmission electron microscopy and critical dimension small-angle x-ray scattering.

TL;DR: Electron Backscatter Diffraction has proven to be a useful tool for characterizing the crystallographic orientation aspects of microstructures at length scales ranging from tens of nanometers to millimeters in the scanning electron microscope (SEM).

TL;DR: Results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment are presented.

TL;DR: The findings of this study apply to all quantitative analyses that involve multi-hit data, but the dead-time will have the greatest effect on the elements that have a significant quantity of ions detected in multi- hit events.

TL;DR: An improved methodology of the Zr specimen preparation was developed which allows fabrication of stable Zr nanotips suitable for FIM and AP applications and the sole suboxide layer has been observed for the first time at very early states of the oxidation.

TL;DR: This work demonstrates a complementary and powerful approach based on tabletop extreme-ultraviolet ptychography that enables quantitative full field imaging with higher contrast than other techniques, and with compositional and topographical information, and will enable dynamic imaging of functioning nanosystems with unprecedented combined spatial and temporal resolution.

TL;DR: Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated.

TL;DR: This paper reviews the evolution of the modeling approach in Atom Probe Tomography and presents some future potential directions in order to improve the method.

TL;DR: Comparison of the UV and green laser data suggests that the green wavelength energy was absorbed less efficiently than the UV wavelength because of differences in absorption at 355 and 532 nm for LiFePO₄.

TL;DR: A summary of some key issues associated with the challenges, and solutions to extract or "mine" fundamental materials science information from that data are provided.

TL;DR: This review was completed in the year that both Max Haider and Ondrej Krivanek reached the age of 65 and it is a pleasure to dedicate it to the two leading actors in the saga of aberration corrector design and construction.

TL;DR: This work theoretically explores how exactly elastic and thermal scattering of the probe confounds the quantitative information one is able to extract about the specimen from an EDS STEM map and shows using simulation how tilting the specimen can reduce the effects of scattering and how it can provide quantitative information about the specimens.

TL;DR: This work is able to show that quantitative chemical information can be precisely and accurately determined from the joined analyze of O-K and Mo-M2,3 edges and should open a new and easier way regarding the quantitative EELS analyses of these compounds.

TL;DR: Using these approaches, data has been achieved from 10-20 nm core-shell nanoparticles that were extracted directly from suspension (i.e. with no chemical modification) with a resolution of better than ± 1 nm.

TL;DR: Using the measured variation in the power spectra amplitude with number of electrons per image it is deduced that water molecules are randomly displaced by a mean squared distance of ∼1.1 ℬ2 for every incident 300 keV e−/Å2.

TL;DR: This paper presents a method where the Voronoi tessellation of the solute atoms and its geometric dual, the Delaunay triangulation is used to test for spatial/chemical randomness of the solid solution as well as extracting the clusters themselves.

TL;DR: This work presents a measurement platform for collecting multiple types of spectroscopy data during high-resolution environmental transmission electron microscopy observations of dynamic processes, made possible by a broadband, high-efficiency, free-space optical system.

TL;DR: It is demonstrated that, in ac-STEM images of compound materials with compositionally distinct atom columns, an additional geometric phase is present in the Fourier transform, and if the structure changes from one area to another in the image, the change in this additional phase will appear as a strain in conventional GPA, even if there is no lattice strain.

TL;DR: This study theoretically demonstrate the imaging of top/sub-surface atomic structures and identify the depth of single dopants, single vacancies and the other point defects within materials by large-angle illumination scanning transmission electron microscopy (LAI-STEM).

TL;DR: The Nye tensor theory is applied to precession electron diffraction automated crystallographic orientation mapping (PED-ACOM) data acquired using a transmission electron microscope (TEM) in order to visualize the dislocation structures present in a quantitative manner.

TL;DR: A simple visible light model is used to demonstrate a proof-of-principle of a new reconstruction algorithm that can cope with the difficulty of three-dimensional scattering effects in tilt-series reconstruction and compare it with the aperture-scanning method.