Existing devices for communicating information to computers are bulky, slow use, or unreliable. Dasher is a new interface incorporating language modelling and driven by continuous two-dimensional gestures, e.g. mouse, touchscreen, eye-tracker. Tests have shown that this device can be used enter text at rate of up 34 words per minute, compared with typical ten-finger keyboard typing 40-60 minute. Although the slower than conventional keyboard, it small simple, could on personal data...

Abstract Delicate structures (such as biological samples, organic films for polymer electronics and adsorbate layers) suffer degradation under the energetic probes of traditional microscopies. Furthermore, charged nature these presents difficulties when imaging with electric or magnetic fields, insulating materials where addition a conductive coating is not desirable. Scanning helium microscopy able to image such completely non-destructively by taking advantage neutral beam chemically,...

Accurate and reliable measurements of three-dimensional surface structures are important for a broad range technological research applications, including materials science, nanotechnology, biomedical research. Scanning helium microscopy (SHeM) uses low-energy (64 meV) neutral atoms as the imaging probe particles, providing highly sensitive delicate approach to measuring topography. To date, topographic SHeM have been largely qualitative, but with advent heliometric stereo method - technique...

Free-jet atomic, cluster, and molecular sources are typically used to produce beams of low-energy, neutral particles find application in a wide array technologies, from atom microscopes instruments for surface processing. We present simple analytical theory that is applicable many these sources, when (i) the nozzle-skimmer distance such free flow achieved (ii) there negligible interference within skimmer itself. The utility model demonstrated by comparing experimental data with calculations...

A method for measuring helium atom diffraction with micron-scale spatial resolution is demonstrated in a scanning microscope (SHeM) and applied to study spot on the (100) plane of lithium fluoride (LiF) crystal. The positions observed peaks provide an accurate measurement local lattice spacing, while combination close-coupled scattering calculations Monte Carlo ray-tracing simulations reproduce main variations diffracted intensity. Subsequently, results are used enhance image contrast by at...

The phenomenology of zeolite collapse is outlined, drawing on recent synchrotron x-ray diffraction experiments and computer simulations low density cage structures like A Y. Attention drawn to the importance polyamorphism in destabilizing this type microporous crystal its role order-disorder as well amorphous-amorphous transitions, together with associated differences entropy between polyamorphic phases precursor zeolite. Magic angle spinning NMR inelastic scattering are used highlight...

We present the first direct experimental measurement of defect-induced lifetime shortening acoustic surface phonons. Defects are found to contribute a temperature-independent component linewidths Rayleigh wave phonons on Ni(111) surface. also characterized increase in phonon scattering with both defect density and vector. A quantitative estimate rate between modes line defects is extracted from data for time. Published by American Physical Society 2024

Three-dimensional mapping of surface structures is important in a wide range biological, technological, healthcare, and research applications. Neutral helium atom beams have been established as sensitive probe topography already enabled structural information to be obtained from delicate samples where conventional probes would cause damage. Here, we empirically demonstrate, for the first time, reconstruction complete profile using measurements modified scanning microscope heliometric stereo...

Measurements of the atomic-scale motion H and D atoms on Pt(111) surface, above crossover temperature to deep tunneling, are presented. The results indicate that quantum effects significant up highest studied (250 K). is shown correspond nearest neighbor hopping diffusion a well defined fcc (111) lattice. measurements provide information adiabatic potential both adsorption site transition state give strong empirical support for dissipative transition-state theory description contribution motion.

Helium spin echo experiments combined with ab initio-based Langevin molecular dynamics simulations are used to quantify the adsorbate-substrate coupling during thermal diffusion of Na atoms on Cu(111). An analysis trajectories within local density friction approximation allows contribution from electron-hole pair excitations be separated total energy dissipation. Despite minimal electronic coefficient and relatively small mass mismatch Cu promoting efficient phononic dissipation, about...

The design of a high-efficiency mass spectrometer is described, aimed at residual gas detection low species using low-energy electron impact, with particular applications in helium atom microscopy and atomic or molecular scattering. instrument consists an extended ionization volume, where electrons emitted from hot filament are confined solenoidal magnetic field to give high probability. Electron space charge used confine extract the ions formed, which then passed through sector filter...

Sulfur vacancy defects mediate a wide range of optoelectronic properties in MoS2, with precise control defect density allowing for tuneable devices. However, accurate measurement monolayer and few-layer samples poses challenge due to their small scattering cross-sections photon or electron probes. Conventional lab-based techniques such as Raman photoluminescence can infer approximate micro-scale via properties, but they require validation using stoichiometric beam-line XPS. We introduce an...

We present helium atom micro-diffraction as an ideal technique for characterization of 2D materials due to its ultimate surface sensitivity combined with sub-micron spatial resolution. Thermal energy neutral scatters from the valence electron density, 2-3A above ionic cores a surface, making studying materials, where other approaches can struggle small interaction cross-sections few-layer samples. Sub-micron resolution is key development in scattering allow measurements device-scale...

Abstract Scanning helium microscopy is an emerging form of using thermal energy neutral atoms as the probe particle. The very low combined with lack charge gives technique great potential for studying delicate systems, and possibility several new forms contrast. To date, images have been dominated by topographic contrast, relating to height angle surface. Here we present data showing contrast resulting from specular reflection diffraction atomic lattice lithium fluoride. signature evident...

Abstract The interfacial behaviour of water remains a central question to fields as diverse protein folding, friction and ice formation. While the properties at interfaces differ from those in bulk, major gaps our knowledge limit understanding molecular level. Information concerning microscopic motion comes mostly computation and, on an atomic scale, is largely unexplored by experiment. Here, we provide detailed insight into monomers graphene surface. displays remarkably strong signatures...

In understanding the nature of contrast in emerging field neutral helium microscopy, it is important to identify if there an atom-surface scattering distribution that can be expected apply broadly across a range sample surfaces. Here we present results acquired scanning microscope (SHeM) under typical operating conditions, from surfaces their native state, i.e. without any specialist preparation. We observe diffuse scattering, with approximately cosine centred about surface normal. The...