Nanoscale analysis of frozen honey by atom probe tomography.

Three-dimensional reconstruction of the analysed volume is one of the main goals of atom probe tomography (APT) and can deliver nearly atomic resolution (~ 0.2 nm spatial resolution) and chemical information with a mass sensitivity down to the ppm range. Extending this technique to frozen biological systems would have an enormous impact on the structural analysis of biomolecules.

A Modular Atom Probe Concept: Design, Operational Aspects, and Performance of an Integrated APT-FIB/SEM Solution.

Atomic probe tomography (APT) is able to generate three-dimensional chemical maps in atomic resolution. The required instruments for APT have evolved over the last 20 years from an experimental to an established method of materials analysis. Here, we describe the realization of a new modular instrument concept that allows the direct attachment of APT to a dual-beam SEM microscope with the main achievement of fast and direct sample transfer and high flexibility in chamber and component configuration.

Atom Probe Study of 1-Octadecanethiol Self-Assembled Monolayers on Platinum (111) and (200) Surfaces.

Atom probe tomography measurements of self-assembled monolayers of 1-octadecanethiol on platinum tips were performed and their fragmentation behavior under the influence of different laser powers was investigated. The carbon backbone evaporates in the form of small hydrocarbon fragments consisting of one to four carbon atoms, while sulfur evaporates exclusively as single ions. The carbon molecules evaporate at very low fields of 5.

Optimizing the plasma oxidation of aluminum gate electrodes for ultrathin gate oxides in organic transistors.

A critical requirement for the application of organic thin-film transistors (TFTs) in mobile or wearable applications is low-voltage operation, which can be achieved by employing ultrathin, high-capacitance gate dielectrics. One option is a hybrid dielectric composed of a thin film of aluminum oxide and a molecular self-assembled monolayer in which the aluminum oxide is formed by exposure of the surface of the aluminum gate electrode to a radio-frequency-generated oxygen plasma. This work investigates how the properties of such dielectrics are affected by the plasma power and the duration of the plasma exposure.

Nonlinear elastic aspects of multi-component iron oxide core-shell nanowires by means of atom probe tomography, analytical microscopy, and nonlinear mechanics.

One-dimensional objects as nanowires have been proven to be building blocks in novel applications due to their unique functionalities. In the realm of magnetic materials, iron-oxides form an important class by providing potential solutions in catalysis, magnetic devices, drug delivery, or in the field of sensors. The accurate composition and spatial structure analysis are crucial to describe the mechanical aspects and optimize strategies for the design of multi-component NWs.

Evaporation and Fragmentation of Organic Molecules in Strong Electric Fields Simulated with DFT.

Atom probe tomography allows us to measure the three-dimensional composition of materials with up to atomic resolution by evaporating the material using high electric fields. Initially developed for metals, it is increasingly used for covalently bound structures. To aid the interpretation of the obtained fragmentation pattern, we modeled the fragmentation and desorption of self-assembled monolayers of thiolate molecules on a gold surface in strong electrostatic fields using density functional theory.

Extracting the shape of nanometric field emitters.

The high resolution nanoanalysis by atom probe tomography is based on needle-shaped samples that represent nanometric field emitters with typical curvature radii of 50 nm. After field desorption and detection of a large set of atoms, the sample volume has to be numerically reconstructed. Conventionally, this reconstruction is performed with the assumption of a hemispherical apex.