Showing papers in "Ultramicroscopy in 2014"

TL;DR: The K2 Summit has the best D QE at low spatial frequencies but with increasing spatial frequency its DQE falls below that of the Falcon II and the FEI Falcon II, and it is found that all three detectors have a betterDQE than film.

TL;DR: It is demonstrated that RevSTEM simultaneously removes the need for a priori structure information to correct distortion, leads to a dramatically improved signal-to-noise ratio, and enables picometer precision and accuracy regardless of drift rate.

TL;DR: Ptychography can recover the spectral response of an object through simultaneous reconstruction of multiple images that represent the object's response to a particular mode present in the illumination, and if the illumination function is also mode-specific, it is shown that it can also solve simultaneously for a multiplicity of such illumination modes.

TL;DR: This paper presents the first successful application of a combined focused ion beam (FIB)/t-EBSD preparation of site-specific APT specimens using the example of grain boundary segregation in technically pure molybdenum.

TL;DR: An adaptation of a cryo-light microscopy stage to permit use of high-numerical aperture objectives and a correlativeCryo-fluorescence and Cryo-electron microscopy workflow together with a fiducial bead-based image correlation procedure, which allows for high-sensitivity and high-resolution fluorescence microscopy of vitrified samples.

TL;DR: A protocol that preserves GFP and mCherry fluorescence in mammalian cells embedded in resin with electron contrast to reveal cellular ultrastructure is presented and it is shown, for the first time, that GFP is stable and active in resin sections in vacuo.

TL;DR: The decrease in density is associated with an enhanced free volume in the shear bands and the increase in density with concomitant changes of the mass, which is further supported by changes in the zero loss and Plasmon signal originating from such sites.

TL;DR: An accelerating voltage of 100-300kV remains a good choice for the majority of TEM or STEM specimens, avoiding the expense of high-voltage microscopy but providing the possibility of atomic resolution even in the absence of lens-aberration correction.

TL;DR: The 3D ultrastructure of the endocytic and autophagic structures is mapped, and clusters of omegasomes arising from ‘hotspots’ on the ER are discovered, proving that immunogold markers and cryo-CLXM can be used to analyse cellular processes that are inaccessible using other imaging modalities.

TL;DR: A method in electron-optics for arbitrarily shaping electron beams into a single desired shape, by precise patterning of a thin-membrane, allowing for nearly-maximal energy transference to the designed shape, and may avoid physical damage and charging effects that are the scorn of commonly-used phase-plates.

TL;DR: Novel aspects of the presented cryoCLEM workflow not only include the implementation of two independent electron dense fluorescent markers to improve the precision of the alignment, but also the ability of obtaining an estimate of the correlation accuracy for each individual object of interest.

TL;DR: It is demonstrated that a precision of few picometers is achievable in lattice measurement using aberration corrected Z-contrast images and a real space approach is developed based on template matching for quantitative lattice analysis using atomic resolution Z- Contrast images.

TL;DR: This work proposes a methodology for extracting an increased level of information by processing a series of data sets suffering from high degree of spatial uncertainty caused by complex multiscale motion during the acquisition process.

TL;DR: It will be shown how this empirical incoherent parametric imaging model can be combined with frozen lattice multislice simulations in order to evolve from a relative toward an absolute quantification of the composition of single atomic columns with mixed atom types.

TL;DR: It is shown that under realistic conditions, the dichroic signal is undetectable for nanoparticles larger than ∼1nm, and this is confirmed by a key experiment with nanometer-sized vortices.

TL;DR: The threshold energy for the MoS₂ material has been found and experimentally verified in the microscope and at energies higher than the energy threshold the authors show surface and edge defects produced by the electron beam irradiation.

TL;DR: The ranges of applicability for four models given different interaction potentials using exit wave simulations are suggested and a practical guideline for when to use each image formation model depending on the spatial frequency, thickness and strength of the interaction potential of a macromolecular complex is presented.

TL;DR: The efficiency of the method makes it suitable for high-throughput EM data collection, and enables the use of a statistical resampling technique, bootstrap, that yields standard deviations of estimated defocus and astigmatism amplitude and angle, thus facilitating the automation of the process of screening out inferior micrograph data.

TL;DR: It is demonstrated that the combination of W-BP and SIRT leads to an improved tomographic reconstruction technique: the weighted SIRT, which is not restricted to TEM tomography but can be applied to all problems sharing single axis imaging geometry.

TL;DR: It is shown that the trend in how the reconstructed tip shape varies with threshold number is so regular that the optimal, or Goldilocks, threshold value corresponds with the peak in the derivative of the RMS difference with respect to the zero threshold curve vs. threshold number.

TL;DR: It is demonstrated that a full 3D characterization of nano-devices requires the combination of both tomography techniques and this combination is particularly useful in helping to understand the evaporation mechanisms and improve APT reconstructions.

TL;DR: A new automated identification and quantification technique for the characterisation of complex ferrite microstructures by electron backscatter diffraction (EBSD).

TL;DR: Multislice simulations were used to analyze the reliability of ADF-STEM imaging and selected-area electron diffraction for determining the thicknesses of MoS2 and WS2 specimens in the aberration-corrected TEM and both techniques proved to be applicable to distinguish monolayers from multilayers using tilt.

TL;DR: It is shown that a long narrow ferromagnetic rod induces a phase shift in the wave-function of passing electrons that approximately describes a helix in the regions near its ends, which could be a simple means of enhancing contrast and gaining additional information from TEM imaged weak phase samples, while also offering the capability to produce vortex beam probes.

TL;DR: The approach utilizes both the Bloch wave formalism and the scattering matrix formalism to generate electron channeling patterns (ECPs) and is adapted to include the effect of lattice defects on the back-scattered electron yield, resulting in a computational algorithm for the simulation of ECCIs.

TL;DR: The properties of SIRT, TVM and DART reconstructions are studied with respect to having only a limited number of electrons available for imaging and applying different angular sampling schemes and overall, SIRT algorithm is the most stable method and insensitive to changes in angular sampling.

TL;DR: Energy-dispersive X-ray (EDX) spectroscopy in the scanning transmission electron microscope (STEM) has been used to demonstrate the presence of size-dependent compositional variation for L12-structured Ni3Al-type gamma-prime (γ') precipitates within a commercial RR1000 Ni-based superalloy.

TL;DR: A novel method to use all this information, instead of just the small subset used in the original 'stepping out' procedure developed in the 1990s, is demonstrated, thus greatly suppressing noise during the deconvolution division.

TL;DR: Measurements of the effective temperature of a pulsed electron source, based on near-threshold photoionization of laser-cooled atoms, are presented, for both nanosecond and femtosecond ionization pulses.

TL;DR: A three-dimensional imaging method is demonstrated by combining through-focal depth sectioning and traditional tilt-series tomography to reconstruct extended objects, with high-resolution, in all three dimensions, and the large convergence angle in aberration corrected instruments now becomes a benefit and not a hindrance to higher quality reconstructions.