Adsorption of water on clean aluminum by measurement of work function changes

Clean surfaces were produced on bulk aluminum samples by a new cutting procedure inside an ultra-high vacuum system. This cutting technique made it possible to stabilize the reference electrode of a vibrating capacitor by equilibration with the gas. Adsorption of water on the clean surfaces was studied by following changes in the work function of the surface at various temperatures and water vapor pressures. Water chemisorbed on the aluminum causing a work function change of − 1.4 V at one monolayer. The rate and amount of chemisorption were negatively dependent on temperature. The characteristics of the work function changes lead to the conclusion that the water chemisorbs by a precursor mechanism.     

Measurements of magneto-Rayleigh-Taylor instability growth during the implosion of initially solid Al tubes driven by the 20-MA, 100-ns Z facility

The first controlled experiments measuring the growth of the magneto-Rayleigh-Taylor instability in fast (～100 ns) Z-pinch plasmas are reported. Sinusoidal perturbations on the surface of an initially solid Al tube (liner) with wavelengths of 25-400 μm were used to seed the instability. Radiographs with 15 μm resolution captured the evolution of the outer liner surface. Comparisons with numerical radiation magnetohydrodynamic simulations show remarkably good agreement down to 50 μm wavelengths.     

Ion channeling study of defects in CuInTe2 single crystals

Ion channeling spectra of as-grown CuInTe₂ single crystals are measured using a 2 MeV ⁴He⁺ analysing beam. It is found that the measured minimum yields cannot be explained within a model of randomly distributed non-interacting point defects caused by deviations from ideal stoichiometry. A model with extended defects due to vacancy clustering and dislocation formation is proposed to interprete the experimental results.     

The effects of surface topography on the method of caustics

An investigation was performed to establish the effects of surface topography on the determination of stress intensity factors of opaque components using the method of caustics. Theoretical predictions of caustics produced by curved surfaces were generated and validated by experiment. The errors introduced for stress intensity factors determined at various radii of curvature were assessed. It was found that relatively small surface curvatures caused significant errors in the stress intensity factor. These errors were affected by the initial radius, load and material properties.     

Modification of the CuInSe2 Crystal Surface during Polishing and Annealing

The RBS/channelling technique was used to study the near-surface damage characteristics of CuInSe₂ crystals after polishing with 0.05 μm grade alumina and subsequent annealing up to temperatures of 600 °C. A comparative RUMP and damage density depth profile analysis of the channelling spectra revealed a polish-induced near-surface disordered layer with a thickness close to 40 nm. Up to annealing temperatures of about 400 °C a gradual overall decrease of the defect density in the damaged layer is observed without detectable changes in its thickness. An indium-rich surface layer is formed after vacuum annealing at 600 °C.