David J. Larson

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Local extraction electrodes offer several crucial advantages for operation of atom probes. Because of the proximity of the local extraction electrode to the specimen, the electric field produced at the specimen apex by a given voltage is enhanced and the voltage required for field evaporation is reduced. In a voltage-pulsed atom probe, the absolute(More)
A case of ovine listeriosis was examined in a flock of sheep. The index case was a male lamb, which was part of a flock of 85 sheep located in central Iowa. Because the sheep were raised on a premise where soybean sprouts were also cultivated for the organic foods market, the potential of a public health concern was addressed. To identify the source of(More)
Techniques for the rapid preparation of atom-probe samples extracted directly from a Si wafer are presented and discussed. A systematic mounting process to a standardized microtip array allows approximately 12 samples to be extracted from a near-surface region and mounted for subsequent focused-ion-beam sharpening in a short period of time, about 2h. In(More)
A real-space technique for finding structural information in atom probe tomographs, spatial distribution maps (SDM), is described. The mechanics of the technique are explained, and it is then applied to some test cases. Many applications of SDM in atom probe tomography are illustrated with examples including finding crystal lattices, correcting lattice(More)
© Elsevier Science Inc., 2000. All rights reserved. 1044-5803/00/$–see front matter 655 Avenue of the Americas, New York, NY 10010 PII S1044-5803(99)00055-8 59 Local Electrode Atom Probes Thomas F. Kelly* and David J. Larson† *Department of Materials Science and Engineering, University of Wisconsin, Madison, WI 53706; and †Metals and Ceramics Division, Oak(More)
The ability to accurately reconstruct original spatial positions of field-evaporated ions emitted from a surface is fundamental to the success of atom probe tomography. As such, a clear understanding of the evolution of specimen shape and the resultant ions' trajectories during field evaporation plays an important role in improving reconstruction accuracy.(More)
Atom-probe tomography (APT) is currently the only analytical technique that, due to its spatial resolution and detection efficiency, has the potential to measure the carbon isotope ratios of individual nanodiamonds. We describe three different sample preparation protocols that we developed for the APT analysis of meteoritic nanodiamonds at sub-nm resolution(More)
Several FIB-based methods that have been developed to fabricate needle-shaped atom probe specimens from a variety of specimen geometries, and site-specific regions are reviewed. These methods have enabled electronic device structures to be characterized. The atom probe may be used to quantify the level and range of gallium implantation and has demonstrated(More)
Atom-probe tomography analysis of complex multilayer structures is a promising avenue for studying interfacial properties. However, significant artefacts in the three-dimensional reconstructed data arise due to the field evaporation process. To clarify the origin and impact of these artefacts for a FeCoB/FeCo/MgO/FeCo/IrMn multilayer, tip shapes were(More)
Atom probe tomography stands out from other materials characterisation techniques mostly due to its capacity to map individual atoms in three-dimensions with high spatial resolution. The methods used to transform raw detector data into a three-dimensional reconstruction have, comparatively to other aspects of the technique, evolved relatively little since(More)