218 research outputs found
When does a newcomer contribute to a better performance? A multi-agent study on self-organising processes of task allocation
Characterization of carbon contamination under ion and hot atom bombardment in a tin-plasma extreme ultraviolet light source
Molecular contamination of a grazing incidence collector for extreme
ultraviolet (EUV) lithography was experimentally studied. A carbon film was
found to have grown under irradiation from a pulsed tin plasma discharge. Our
studies show that the film is chemically inert and has characteristics that are
typical for a hydrogenated amorphous carbon film. It was experimentally
observed that the film consists of carbon (~70 at. %), oxygen (~20 at. %) and
hydrogen (bound to oxygen and carbon), along with a few at. % of tin. Most of
the oxygen and hydrogen are most likely present as OH groups, chemically bound
to carbon, indicating an important role for adsorbed water during the film
formation process. It was observed that the film is predominantly sp3
hybridized carbon, as is typical for diamond-like carbon. The Raman spectra of
the film, under 514 and 264 nm excitation, are typical for hydrogenated
diamond-like carbon. Additionally, the lower etch rate and higher energy
threshold in chemical ion sputtering in H2 plasma, compared to
magnetron-sputtered carbon films, suggests that the film exhibits diamond-like
carbon properties.Comment: 18 pages, 10 figure
Broncho-tracheal Compression Caused by Oesophageal Impaction After Bilateral Lung Transplantation
From Geometry to Activity: A Quantitative Analysis of WO3/Si Micropillar Arrays for Photoelectrochemical Water Splitting
The photoelectrochemical (PEC) activity of microstructured electrodes remains low despite the highly enlarged surface area and enhanced light harvesting. To obtain a deeper understanding of the effect of 3D geometry on the PEC performance, wellâdefined WO3/nâSi and WO3/pnâSi micropillar arrays are fabricated and subjected to a quantitative analysis of the relationship between the geometry of the micropillars (length, pitch) and their PEC activity. For WO3/nâSi micropillars, it is found that the photocurrent increases for WO3/nâSi pillars, but not in proportion to the increase in surface area that results from increased pillar length or reduced pillar pitch. Optical simulations show that a reduced pillar pitch results in areas of low light intensity due to a shadowing effect. For WO3/pnâSi micropillar photoelectrodes, the pân junction enhances the photocurrent density up to a factor of 4 at low applied bias potential (0.8 V vs RHE) compared to the WO3/nâSi. However, the enhancement in photocurrent density increases first and then decreases with reduced pillar pitch, which scales with the photovoltage generated by the pân junction. This is related to an increased dead layer of the pân junction Si surface, which results in a decreased photovoltage even though the total surface area increases.</p
Surface and sub-surface thermal oxidation of thin ruthenium films
A mixed 2D (film) and 3D (nano-column) growth of ruthenium oxide has been experimentally observed for thermally oxidized polycrystalline ruthenium thin films. Furthermore, in situ x-ray reflectivity upon annealing allowed the detection of 2D film growth as two separate layers consisting of low density and high density oxides. Nano-columns grow at the surface of the low density oxide layer, with the growth rate being limited by diffusion of ruthenium through the formed oxide film. Simultaneously, with the growth of the columns, sub-surface high density oxide continues to grow limited by diffusion of oxygen or ruthenium through the oxide fil
Erosion yields of carbon under various plasma conditions in Pilot-PSI
Fine-grain graphite targets have been exposed to ITER divertor relevant
plasmas in Pilot-PSI to address material migration issues in fusion devices.
Optical emission spectroscopy and mass loss measurements have been employed to
quantify gross chemical erosion and net erosion yields, respectively. Effects
of the ion impact energy and target geometry on carbon erosion yields have been
studied. It is concluded that temporal evolution of gross chemical erosion is
strongly connected with changes in morphology of plasma exposed surfaces. The
net carbon erosion yield is increased when the targets are partly covered by
insulating boron-nitride rings.Comment: 14 pages, 4 figures, Contribution to the 19th International
Conference on Plasma Surface Interaction
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