Adsorption of oxygen on silver single crystal surfaces

ALIS Corporation has developed a new helium ion microscope which has many advantages over both traditional scanning electron microscopes (SEMs) and focused ion beams (FIBs). This new technology is expected to produce an ultimate focused spot size of 0.25nm. This high resolution is attributed to the high source brightness (B>4×109A∕cm2sr), low energy spread (ΔE∕E∼2×10−5), and small diffraction effects (λ∼80fm). The interaction of helium ions with matter offers several valuable contrast mechanisms and a surface interaction volume which is much smaller than a SEM or conventional FIB.

https://www.iap.uni-jena.de/iapmedia/de/Lecture/Nanomaterials1367272800/NanoMat13_Paper_optional_03a.pdf

Helium ion microscope: A new tool for nanoscale microscopy and metrology

Helium Ion Microcopy (HIM) based on Gas Field Ion Sources (GFIS) represents a new ultra high resolution microscopy and nano-fabrication technique. It is an enabling technology that not only provides imagery of conducting as well as uncoated insulating nano-structures but also allows to create these features. The latter can be achieved using resists or material removal due to sputtering. The close to free-form sculpting of structures over several length scales has been made possible by the extension of the method to other gases such as Neon. A brief introduction of the underlying physics as well as a broad review of the applicability of the method is presented in this review.

/pdf/helium-ion-microscopy-20lveyia0z.pdf

Helium ion microscopy

This Perspective illustrates how the presence of internal and external electric fields can affect catalytic activity and selectivity, with a focus on heterogeneous catalysts. Specifically, experimental investigations of the electric field influence on catalyst selectivity in pulsed field mass desorption microscopes, scanning tunneling microscopes, probe–bed–probe reactors, continuous-circuit reactors, and capacitor reactors are described. Through these examples, we show how the electric field, whether externally applied or intrinsically present, can affect the behavior of a wide number of materials relevant to catalysis. We review some of the theoretical methods that have been used to elucidate the influence of external electric fields on catalytic reactions, as well as the application of such methods to selective methane activation. In doing so, we illustrate the breadth of possibilities in field-assisted catalysis.

Elucidating the Roles of Electric Fields in Catalysis: A Perspective

3 Science et Ingenierie des MAteriaux et Procedes (SIMaP) - UMR 5266 CNRS-Grenoble INP-UJF, Saint-Martin-d'Heres, France Abstract: This article addresses gaps in definitions and a lack of standard measurement techniques to assess the spatial resolution in atom probe tomography. This resolution is known to be anisotropic, being better in-depth than laterally. Generally the presence of atomic planes in the tomographic reconstruction is considered as being a sufficient proof of the quality of the spatial resolution of the instrument. Based on advanced spatial distribution maps, an analysis methodology that interrogates the local neighborhood of the atoms within the tomographic reconstruction, it is shown how both the in-depth and the lateral resolution can be quantified. The influences of the crystallography and the temperature are investigated, and models are proposed to explain the observed results. We demonstrate that the absolute value of resolution is specimen specific.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1431927609991267

W.A. Schmidt

Papers

Electrostatic fields above individual atoms

Local electric fields at individual atomic surface sites: field ion appearance energy measurements

The critical energy deficit of field emitted ions

Field desorption and field evaporation of metals: In memoriam Professor J.H. Block

On the full-width-at-half-maximum of field ion energy distributions