No abstract

No abstract

A table-top XUV-source based on pseudospark plasma-emission is operated with pure gases (Ar, O 2 and N 2 ) and mixtures (Ar/He, O 2 /He and N 2 /He) at different pressures and input voltages, and the dependence of these parameters on the source repetition rate, XUV-photon flux, XUVpower and emission spectra are discussed. Operating the source with Ar, it is shown that the repetition rate is increased if the pressure or input voltage from the power supply are increased. The intensity on the spectra and XUV photon flux (for Ar and Ar/He) are observed to decrease with increment of pure gas pressure and to increase with the addition of He to the pure gases. Repetition rates of up to 25 Hz and 10 13 photons/(2psr pulse) for λ between 7 and 16 nm and XUV-power of up to 10 mW/(2psr) have been observed. Stability measurements and determination of optimal sample position with respect to the highest number of photons are also presented. Fluctuations on the plasma emission up to 10% are observed.

A Y/Mo multilayer coating, optimized for top reflectivity at λ=12  nm, has been nano-inspected after long-term operation at the in-house soft x-ray laser. The surface and optical inspections were complemented by electron microscopy on cross sections, prepared with focused ion beam technology. A factor of 2.5 loss of reflectivity in the exposed area (ca. 30% relative loss every 100 shots), with concomitant nanoscale photodamage and particle fallout, was found. The x-ray-laser-induced damage extended as deep as 250 nm beneath the surface and as wide as the millimeter spot size.

Nanoscale depth profiling analysis of a CoNCN-coated electrode for water oxidation catalysis was carried out using table-top extreme ultraviolet (XUV) laser ablation time-of-flight mass spectrometry. The self-developed laser operates at λ = 46.9 nm and represents factor of 4 reduction in wavelength with respect to the 193 nm excimer laser. The reduction of the wavelength is an alternative approach to the reduction of the pulse duration, to enhance the ablation characteristics and obtain smaller quasi-nondestructive ablation pits. Such a XUV-laser ablation method allowed distinguishing different composite components of the catalyst-Nafion blend, used to modify a screen-printed carbon electrode surface. Chemical information was extracted by fragment assignment and relative amplitude analysis of the mass spectrometry peaks. Pure Nafion and the exposed carbon substrate were compared as references. Material specific fragments were clearly identified by the detected nonoverlapping mass-to-charge peaks of Nafion and CoNCN. Three dimensional mapping of relevant mass peak amplitudes was used to determine the lateral distribution and to generate depth profiles from consecutive laser pulses. Evaluating the profiles of pristine electrodes gave insight into fragmentation behavior of the catalyst in a functional ionomer matrix and comparison of post-catalytic electrodes revealed spots of thin localized Co residues.